1
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Chang ZW, Hao WC, Liu X. Design of higher Chern number two-band structures from topological defect perspective. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:425501. [PMID: 38848730 DOI: 10.1088/1361-648x/ad5599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 06/07/2024] [Indexed: 06/09/2024]
Abstract
In this article, we propose two methods for designing higher Chern number models from the topological defect perspective. Based on the fact that the Chern number is equal to a summation of the charges of meron defects, we show that the higher Chern number structures can be realized by either moving the positions of merons or increasing the amount of them. The combination of the two methods is also verified to be a viable approach. We shall construct several models and investigate their energy spectrum. More than one gapless state can be observed on the edges of these models. Expectedly, our theory promises to provide not only a simple approach to obtain the Chern number without computing any integrals, but also a practical technique for new material design.
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Affiliation(s)
- Zhi-Wen Chang
- School of Physics and Optoelectronic Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Wei-Chang Hao
- School of Physics, Beihang University, Beijing 102206, People's Republic of China
| | - Xin Liu
- School of Physics and Optoelectronic Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China
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2
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Chen B, Liu X, Li Y, Tay H, Taniguchi T, Watanabe K, Chan MHW, Yan J, Song F, Cheng R, Chang CZ. Even-Odd Layer-Dependent Exchange Bias Effect in MnBi 2Te 4 Chern Insulator Devices. NANO LETTERS 2024; 24:8320-8326. [PMID: 38935843 DOI: 10.1021/acs.nanolett.4c01597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Magnetic topological materials with coexisting magnetism and nontrivial band structures exhibit many novel quantum phenomena, including the quantum anomalous Hall effect, the axion insulator state, and the Weyl semimetal phase. As a stoichiometric layered antiferromagnetic topological insulator, thin films of MnBi2Te4 show fascinating even-odd layer-dependent physics. In this work, we fabricate a series of thin-flake MnBi2Te4 devices using stencil masks and observe the Chern insulator state at high magnetic fields. Upon magnetic field training, a large exchange bias effect is observed in odd but not in even septuple layer (SL) devices. Through theoretical calculations, we attribute the even-odd layer-dependent exchange bias effect to the contrasting surface and bulk magnetic properties of MnBi2Te4 devices. Our findings reveal the microscopic magnetic configuration of MnBi2Te4 thin flakes and highlight the challenges in replicating the zero magnetic field quantum anomalous Hall effect in odd SL MnBi2Te4 devices.
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Affiliation(s)
- Bo Chen
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Xiaoda Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yuhang Li
- School of Physics, Nankai University, Tianjin 300071, China
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, United States
| | - Han Tay
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jiaqiang Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Ran Cheng
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, United States
- Department of Physics and Astronomy, University of California, Riverside, California 92521, United States
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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3
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Sahoo M, Onuorah IJ, Folkers LC, Kochetkova E, Chulkov EV, Otrokov MM, Aliev ZS, Amiraslanov IR, Wolter AUB, Büchner B, Corredor LT, Wang C, Salman Z, Isaeva A, De Renzi R, Allodi G. Ubiquitous Order-Disorder Transition in the Mn Antisite Sublattice of the (MnBi 2Te 4)(Bi 2Te 3) n Magnetic Topological Insulators. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2402753. [PMID: 38973332 DOI: 10.1002/advs.202402753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/22/2024] [Indexed: 07/09/2024]
Abstract
Magnetic topological insulators (TIs) herald a wealth of applications in spin-based technologies, relying on the novel quantum phenomena provided by their topological properties. Particularly promising is the (MnBi2Te4)(Bi2Te3)n layered family of established intrinsic magnetic TIs that can flexibly realize various magnetic orders and topological states. High tunability of this material platform is enabled by manganese-pnictogen intermixing, whose amounts and distribution patterns are controlled by synthetic conditions. Here, nuclear magnetic resonance and muon spin spectroscopy, sensitive local probe techniques, are employed to scrutinize the impact of the intermixing on the magnetic properties of (MnBi2Te4)(Bi2Te3)n and MnSb2Te4. The measurements not only confirm the opposite alignment between the Mn magnetic moments on native sites and antisites in the ground state of MnSb2Te4, but for the first time directly show the same alignment in (MnBi2Te4)(Bi2Te3)n with n = 0, 1 and 2. Moreover, for all compounds, the static magnetic moment of the Mn antisite sublattice is found to disappear well below the intrinsic magnetic transition temperature, leaving a homogeneous magnetic structure undisturbed by the intermixing. The findings provide a microscopic understanding of the crucial role played by Mn-Bi intermixing in (MnBi2Te4)(Bi2Te3)n and offer pathways to optimizing the magnetic gap in its surface states.
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Affiliation(s)
- Manaswini Sahoo
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Ifeanyi John Onuorah
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Laura Christina Folkers
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Ekaterina Kochetkova
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Van der Waals-Zeeman Institute, Department of Physics and Astronomy, University of Amsterdam, Science Park 094, Amsterdam, 1098 XH, Netherlands
| | - Evgueni V Chulkov
- Donostia International Physics Center, Sebastián, 20018 Donostia-San, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco UPV/EHU, Donostia-San Sebastián, 20018, Spain
- Centro de Física de Materiales (CFM-MPC), Centro Mixto (CSIC-UPV/EHU), Donostia-San Sebastián, 20018, Spain
- Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Mikhail M Otrokov
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
| | - Ziya S Aliev
- Baku State University, Baku, AZ1148, Azerbaijan
- Institute of Physics Ministry of Science and Education Republic of Azerbaijan, Baku, AZ1143, Azerbaijan
| | - Imamaddin R Amiraslanov
- Baku State University, Baku, AZ1148, Azerbaijan
- Institute of Physics Ministry of Science and Education Republic of Azerbaijan, Baku, AZ1143, Azerbaijan
| | - Anja U B Wolter
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
| | - Bernd Büchner
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | | | - Chennan Wang
- Laboratory for Muon Spin Spectroscopy, Paul-Scherrer-Institute, Villigen PSI, CH-5232, Switzerland
| | - Zaher Salman
- Laboratory for Muon Spin Spectroscopy, Paul-Scherrer-Institute, Villigen PSI, CH-5232, Switzerland
| | - Anna Isaeva
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Van der Waals-Zeeman Institute, Department of Physics and Astronomy, University of Amsterdam, Science Park 094, Amsterdam, 1098 XH, Netherlands
- Faculty of Physics, Technical University of Dortmund, Otto-Hahn-Str. 4, 44221, Dortmund, Germany
- Research Center Future Energy Materials and Systems (RC FEMS), Germany
| | - Roberto De Renzi
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Giuseppe Allodi
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
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4
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Yan Q, Li H, Jiang H, Sun QF, Xie XC. Rules for dissipationless topotronics. SCIENCE ADVANCES 2024; 10:eado4756. [PMID: 38838153 DOI: 10.1126/sciadv.ado4756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/01/2024] [Indexed: 06/07/2024]
Abstract
Topological systems hosting gapless boundary states have attracted huge attention as promising components for next-generation information processing, attributed to their capacity for dissipationless electronics. Nevertheless, recent theoretical and experimental inquiries have revealed the emergence of energy dissipation in precisely quantized electrical transport. Here, we present a criterion for the realization of truly no-dissipation design, characterized as Nin = Ntunl + Nbs, where Nin, Ntunl, and Nbs represent the number of modes participating in injecting, tunneling, and backscattering processes, respectively. The key lies in matching the number of injecting, tunneling, and backscattering modes, ensuring the equilibrium among all engaged modes inside the device. Among all the topological materials, we advocate for the indispensability of Chern insulators exhibiting higher Chern numbers to achieve functional devices and uphold the no-dissipation rule simultaneously. Furthermore, we design the topological current divider and collector, evading dissipation upon fulfilling the established criterion. Our work paves the path for developing the prospective topotronics.
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Affiliation(s)
- Qing Yan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Hailong Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Hua Jiang
- Interdisciplinary Center for Theoretical Physics and Information Sciences (ICTPIS), Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Qing-Feng Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Hefei National Laboratory, Hefei 230088, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Interdisciplinary Center for Theoretical Physics and Information Sciences (ICTPIS), Fudan University, Shanghai 200433, China
- Hefei National Laboratory, Hefei 230088, China
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5
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Zhang X, Li Y, Lu Q, Xiang X, Sun X, Tang C, Mahdi M, Conner C, Cook J, Xiong Y, Inman J, Jin W, Liu C, Cai P, Santos EJG, Phatak C, Zhang W, Gao N, Niu W, Bian G, Li P, Yu D, Long S. Epitaxial Growth of Large-Scale 2D CrTe 2 Films on Amorphous Silicon Wafers With Low Thermal Budget. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2311591. [PMID: 38426690 DOI: 10.1002/adma.202311591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/27/2024] [Indexed: 03/02/2024]
Abstract
2D van der Waals (vdW) magnets open landmark horizons in the development of innovative spintronic device architectures. However, their fabrication with large scale poses challenges due to high synthesis temperatures (>500 °C) and difficulties in integrating them with standard complementary metal-oxide semiconductor (CMOS) technology on amorphous substrates such as silicon oxide (SiO2) and silicon nitride (SiNx). Here, a seeded growth technique for crystallizing CrTe2 films on amorphous SiNx/Si and SiO2/Si substrates with a low thermal budget is presented. This fabrication process optimizes large-scale, granular atomic layers on amorphous substrates, yielding a substantial coercivity of 11.5 kilo-oersted, attributed to weak intergranular exchange coupling. Field-driven Néel-type stripe domain dynamics explain the amplified coercivity. Moreover, the granular CrTe2 devices on Si wafers display significantly enhanced magnetoresistance, more than doubling that of single-crystalline counterparts. Current-assisted magnetization switching, enabled by a substantial spin-orbit torque with a large spin Hall angle (85) and spin Hall conductivity (1.02 × 107 ℏ/2e Ω⁻¹ m⁻¹), is also demonstrated. These observations underscore the proficiency in manipulating crystallinity within integrated 2D magnetic films on Si wafers, paving the way for large-scale batch manufacturing of practical magnetoelectronic and spintronic devices, heralding a new era of technological innovation.
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Affiliation(s)
- Xiaoqian Zhang
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, 211189, China
| | - Yue Li
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Qiangsheng Lu
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
- Material Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Xueqiang Xiang
- School of Microelectronics, University of Science and Technology of China, Hefei, 230026, China
| | - Xiaozhen Sun
- School of Microelectronics, University of Science and Technology of China, Hefei, 230026, China
| | - Chunli Tang
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, 36849, USA
| | - Muntasir Mahdi
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, 36849, USA
| | - Clayton Conner
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Jacob Cook
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Yuzan Xiong
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jerad Inman
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Physics, Oakland University, Rochester, MI, 48309, USA
| | - Wencan Jin
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, 36849, USA
- Department of Physics, Auburn University, Auburn, AL, 36849, USA
| | - Chang Liu
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - PeiYu Cai
- Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Elton J G Santos
- Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK
- Higgs Centre for Theoretical Physics, The University of Edinburgh, Edinburgh, EH9 3FD, UK
- Donostia International Physics Center (DIPC), Donostia-San Sebastián, 20018, Basque Country, Spain
| | - Charudatta Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Wei Zhang
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Physics, Oakland University, Rochester, MI, 48309, USA
| | - Nan Gao
- School of Microelectronics, University of Science and Technology of China, Hefei, 230026, China
| | - Wei Niu
- School of Science, Nanjing University of Posts and Telecommunications, Nanjing, 210023, China
| | - Guang Bian
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA
| | - Peng Li
- School of Microelectronics, University of Science and Technology of China, Hefei, 230026, China
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Shibing Long
- School of Microelectronics, University of Science and Technology of China, Hefei, 230026, China
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6
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Han X, Liu Q, Wang Y, Niu R, Qu Z, Wang Z, Li Z, Han C, Watanabe K, Taniguchi T, Song Z, Liu J, Mao J, Han Z, Chittari BL, Jung J, Gan Z, Lu J. Engineering the Band Topology in a Rhombohedral Trilayer Graphene Moiré Superlattice. NANO LETTERS 2024; 24:6286-6295. [PMID: 38747346 DOI: 10.1021/acs.nanolett.4c00948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Moiré superlattices have become a fertile playground for topological Chern insulators, where the displacement field can tune the quantum geometry and Chern number of the topological band. However, in experiments, displacement field engineering of spontaneous symmetry-breaking Chern bands has not been demonstrated. Here in a rhombohedral trilayer graphene moiré superlattice, we use a thermodynamic probe and transport measurement to monitor the Chern number evolution as a function of the displacement field. At a quarter filling of the moiré band, a novel Chern number of three is unveiled to compete with the well-established number of two upon turning on the electric field and survives when the displacement field is sufficiently strong. The transition can be reconciled by a nematic instability on the Fermi surface due to the pseudomagnetic vector field potentials associated with moiré strain patterns. Our work opens more opportunities to active control of Chern numbers in van der Waals moiré systems.
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Affiliation(s)
- Xiangyan Han
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qianling Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yijie Wang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Ruirui Niu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuangzhuang Qu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuoxian Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Chunrui Han
- Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Zhida Song
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 200031, China
| | - Jinhai Mao
- School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Han
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Optoelectronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Bheema Lingam Chittari
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Jeil Jung
- Department of Physics, University of Seoul, Seoul 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul 02504, Korea
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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7
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Bai Y, Zhang L, Mao N, Li R, Chen Z, Dai Y, Huang B, Niu C. Coupled Electronic and Magnonic Topological States in Two-Dimensional Ferromagnets. ACS NANO 2024; 18:13377-13383. [PMID: 38728267 DOI: 10.1021/acsnano.4c03529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Magnetic materials offer a fertile playground for fundamental physics discovery, with not only electronic but also magnonic topological states intensively explored. However, one natural material with both electronic and magnonic nontrivial topologies is still unknown. Here, we demonstrate the coexistence of first-order topological magnon insulators (TMIs) and electronic second-order topological insulators (SOTIs) in 2D honeycomb ferromagnets, giving rise to the nontrivial corner states being connected by the charge-free magnonic edge states. We show that, with C 3 symmetry, the phase factor ± ϕ caused by the next nearest-neighbor Dzyaloshinskii-Moriya interaction breaks the pseudo-spin time-reversal symmetry T , which leads to the split of magnon bands, i.e., the emergence of TMIs with a nonzero Chern number of C = - 1 , in experimentally feasible candidates of MoI3, CrSiTe3, and CrGeTe3 monolayers. Moreover, protected by the C 3 symmetry, the electronic SOTIs characterized by nontrivial corner states are obtained, bridging the topological aspect of fermions and bosons with a high possibility of innovative applications in spintronics devices.
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Affiliation(s)
- Yingxi Bai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Lichuan Zhang
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Ning Mao
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Runhan Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Zhiqi Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Chengwang Niu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
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8
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Li Y, Wang Y, Lian Z, Li H, Gao Z, Xu L, Wang H, Lu R, Li L, Feng Y, Zhu J, Liu L, Wang Y, Fu B, Yang S, Yang L, Wang Y, Xia T, Liu C, Jia S, Wu Y, Zhang J, Wang Y, Liu C. Fabrication-induced even-odd discrepancy of magnetotransport in few-layer MnBi 2Te 4. Nat Commun 2024; 15:3399. [PMID: 38649376 PMCID: PMC11035656 DOI: 10.1038/s41467-024-47779-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
The van der Waals antiferromagnetic topological insulator MnBi2Te4 represents a promising platform for exploring the layer-dependent magnetism and topological states of matter. Recently observed discrepancies between magnetic and transport properties have aroused controversies concerning the topological nature of MnBi2Te4 in the ground state. In this article, we demonstrate that fabrication can induce mismatched even-odd layer dependent magnetotransport in few-layer MnBi2Te4. We perform a comprehensive study of the magnetotransport properties in 6- and 7-septuple-layer MnBi2Te4, and reveal that both even- and odd-number-layer device can show zero Hall plateau phenomena in zero magnetic field. Importantly, a statistical survey of the optical contrast in more than 200 MnBi2Te4 flakes reveals that the zero Hall plateau in odd-number-layer devices arises from the reduction of the effective thickness during the fabrication, a factor that was rarely noticed in previous studies of 2D materials. Our finding not only provides an explanation to the controversies regarding the discrepancy of the even-odd layer dependent magnetotransport in MnBi2Te4, but also highlights the critical issues concerning the fabrication and characterization of 2D material devices.
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Affiliation(s)
- Yaoxin Li
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Yongchao Wang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Zichen Lian
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Hao Li
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
- Department of Physics, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing, 100084, China
| | - Zhiting Gao
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Liangcai Xu
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Huan Wang
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Rui'e Lu
- School of Mechanical and Electric Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Longfei Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Yang Feng
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Jinjiang Zhu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Liangyang Liu
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Yongqian Wang
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Bohan Fu
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Shuai Yang
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Luyi Yang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
- Frontier Science Center for Quantum Information, Beijing, 100084, China
| | - Yihua Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China
| | - Tianlong Xia
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Chang Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yang Wu
- College of Math and Physics, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Jinsong Zhang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
- Frontier Science Center for Quantum Information, Beijing, 100084, China
- Hefei National Laboratory, Hefei, 230088, China
| | - Yayu Wang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
- Frontier Science Center for Quantum Information, Beijing, 100084, China
- Hefei National Laboratory, Hefei, 230088, China
| | - Chang Liu
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872, Beijing, China.
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China.
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9
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Chong SK, Lei C, Cheng Y, Lee SH, Mao Z, MacDonald AH, Wang KL. Exchange-Driven Chern States in High-Mobility Intrinsic Magnetic Topological Insulators. PHYSICAL REVIEW LETTERS 2024; 132:146601. [PMID: 38640375 DOI: 10.1103/physrevlett.132.146601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/25/2024] [Accepted: 03/12/2024] [Indexed: 04/21/2024]
Abstract
The layer-dependent Chern number (C) in MnBi_{2}Te_{4} is characterized by the presence of a Weyl semimetal state in the ferromagnetic coupling. However, the influence of a key factor, namely, the exchange coupling, remains unexplored. This study focuses on characterizing the C=2 state in MnBi_{2}Te_{4}, which is classified as a higher C state resulting from the anomalous n=0 Landau levels (LLs). Our findings demonstrate that the exchange coupling parameter strongly influences the formation of this Chern state, leading to a competition between the C=1 and 2 states. Moreover, the emergence of odd-even LL sequences, resulting from the breaking of LL degeneracy, provides compelling evidence for the strong exchange coupling strength. These findings highlight the significance of the exchange coupling in understanding the behavior of Chern states and LLs in magnetic quantum systems.
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Affiliation(s)
- Su Kong Chong
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
| | - Chao Lei
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Yang Cheng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
| | - Seng Huat Lee
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Zhiqiang Mao
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Allan H MacDonald
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
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10
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Feng J, Zhou X, Xu M, Shi J, Li Y. Layer Control of Magneto-Optical Effects and Their Quantization in Spin-Valley Splitting Antiferromagnets. NANO LETTERS 2024; 24:3898-3905. [PMID: 38525906 DOI: 10.1021/acs.nanolett.3c05052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Magneto-optical effects (MOE), interfacing the fundamental interplay between magnetism and light, have served as a powerful probe for magnetic order, band topology, and valley index. Here, based on multiferroic and topological bilayer antiferromagnets (AFMs), we propose a layer control of MOE (L-MOE), which is created and annihilated by layer-stacking or an electric field effect. The key character of L-MOE is the sign-reversible response controlled by ferroelectric polarization, the Néel vector, or the electric field direction. Moreover, the sign-reversible L-MOE can be quantized in topologically insulating AFMs. We reveal that the switchable L-MOE originates from the combined contributions of spin-conserving and spin-flip interband transitions in spin-valley splitting AFMs, a phenomenon not observed in conventional AFMs. Our findings bridge the ancient MOE to the emergent realms of layertronics, valleytronics, and multiferroics and may hold immense potential in these fields.
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Affiliation(s)
- Jiaqi Feng
- Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Xiaodong Zhou
- Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Meiling Xu
- Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Jingming Shi
- Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Yinwei Li
- Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
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11
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Xue F, Hou Y, Wang Z, Xu Z, He K, Wu R, Xu Y, Duan W. Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures. Natl Sci Rev 2024; 11:nwad151. [PMID: 38312389 PMCID: PMC10833467 DOI: 10.1093/nsr/nwad151] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/24/2023] [Accepted: 04/03/2023] [Indexed: 02/02/2024] Open
Abstract
The quantum anomalous Hall effect (QAHE) has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C = ±1 and the out-of-plane magnetization induced QAHE with high Chern numbers C = ±3 can be realized in a single material candidate, which is composed of van der Waals (vdW) coupled Bi and MnBi2Te4 monolayers. The switching between different phases of QAHE can be controlled in multiple ways, such as applying strain or (weak) magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.
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Affiliation(s)
- Feng Xue
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yusheng Hou
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Center for Neutron Science and Technology, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Zhe Wang
- State Key Laboratory of Surface Physics, Key Laboratory of Computational Physical Sciences, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Zhiming Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Ke He
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California-Irvine, Irvine, CA 92697, USA
| | - Yong Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Tencent Quantum Laboratory, Tencent Technology (Shenzhen) Co. Ltd, Shenzhen 518057, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Wenhui Duan
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
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12
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Zhu K, Cheng Y, Liao M, Chong SK, Zhang D, He K, Wang KL, Chang K, Deng P. Unveiling the Anomalous Hall Response of the Magnetic Structure Changes in the Epitaxial MnBi 2Te 4 Films. NANO LETTERS 2024; 24:2181-2187. [PMID: 38340079 PMCID: PMC10885191 DOI: 10.1021/acs.nanolett.3c04095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Recently discovered as an intrinsic antiferromagnetic topological insulator, MnBi2Te4 has attracted tremendous research interest, as it provides an ideal platform to explore the interplay between topological and magnetic orders. MnBi2Te4 displays distinct exotic topological phases that are inextricably linked to the different magnetic structures of the material. In this study, we conducted electrical transport measurements and systematically investigated the anomalous Hall response of epitaxial MnBi2Te4 films when subjected to an external magnetic field sweep, revealing the different magnetic structures stemming from the interplay of applied fields and the material's intrinsic antiferromagnetic (AFM) ordering. Our results demonstrate that the nonsquare anomalous Hall loop is a consequence of the distinct reversal processes within individual septuple layers. These findings shed light on the intricate magnetic structures in MnBi2Te4 and related materials, offering insights into understanding their transport properties and facilitating the implementation of AFM topological electronics.
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Affiliation(s)
- Kejing Zhu
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Yang Cheng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Menghan Liao
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Su Kong Chong
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Ding Zhang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Ke He
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Kai Chang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Peng Deng
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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13
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Li S, Liu T, Liu C, Wang Y, Lu HZ, Xie XC. Progress on the antiferromagnetic topological insulator MnBi 2Te 4. Natl Sci Rev 2024; 11:nwac296. [PMID: 38213528 PMCID: PMC10776361 DOI: 10.1093/nsr/nwac296] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 10/18/2022] [Accepted: 11/09/2022] [Indexed: 01/13/2024] Open
Abstract
Topological materials, which feature robust surface and/or edge states, have now been a research focus in condensed matter physics. They represent a new class of materials exhibiting nontrivial topological phases, and provide a platform for exploring exotic transport phenomena, such as the quantum anomalous Hall effect and the quantum spin Hall effect. Recently, magnetic topological materials have attracted considerable interests due to the possibility to study the interplay between topological and magnetic orders. In particular, the quantum anomalous Hall and axion insulator phases can be realized in topological insulators with magnetic order. MnBi2Te4, as the first intrinsic antiferromagnetic topological insulator discovered, allows the examination of existing theoretical predictions; it has been extensively studied, and many new discoveries have been made. Here we review the progress made on MnBi2Te4 from both experimental and theoretical aspects. The bulk crystal and magnetic structures are surveyed first, followed by a review of theoretical calculations and experimental probes on the band structure and surface states, and a discussion of various exotic phases that can be realized in MnBi2Te4. The properties of MnBi2Te4 thin films and the corresponding transport studies are then reviewed, with an emphasis on the edge state transport. Possible future research directions in this field are also discussed.
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Affiliation(s)
- Shuai Li
- Department of Physics, Harbin Institute of Technology, Harbin 150001, China
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Tianyu Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Chang Liu
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Hefei National Laboratory, Hefei 230088, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Hefei National Laboratory, Hefei 230088, China
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14
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Bai Y, Li Y, Luan J, Liu R, Song W, Chen Y, Ji PF, Zhang Q, Meng F, Tong B, Li L, Jiang Y, Gao Z, Gu L, Zhang J, Wang Y, Xue QK, He K, Feng Y, Feng X. Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi 2Te 4 thin films. Natl Sci Rev 2024; 11:nwad189. [PMID: 38213514 PMCID: PMC10776363 DOI: 10.1093/nsr/nwad189] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/29/2023] [Accepted: 05/16/2023] [Indexed: 01/13/2024] Open
Abstract
The intrinsic magnetic topological insulator MnBi2Te4 provides a feasible pathway to the high-temperature quantum anomalous Hall (QAH) effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4 thin flakes, it remains a big challenge to achieve molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4 thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4 and to find a way out of the big difficulty in obtaining MnBi2Te4 samples showing quantized transport properties.
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Affiliation(s)
- Yunhe Bai
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Yuanzhao Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Jianli Luan
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Ruixuan Liu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Wenyu Song
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Yang Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Peng-Fei Ji
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Qinghua Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
| | - Fanqi Meng
- School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Bingbing Tong
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Lin Li
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Yuying Jiang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
| | - Zongwei Gao
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Lin Gu
- School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Jinsong Zhang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Hefei National Laboratory, Hefei230088, China
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Hefei National Laboratory, Hefei230088, China
| | - Qi-Kun Xue
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
- Southern University of Science and Technology, Shenzhen518055, China
| | - Ke He
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
- Hefei National Laboratory, Hefei230088, China
| | - Yang Feng
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Xiao Feng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing100084, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
- Hefei National Laboratory, Hefei230088, China
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15
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Wang Y, Ma XM, Hao Z, Cai Y, Rong H, Zhang F, Chen W, Zhang C, Lin J, Zhao Y, Liu C, Liu Q, Chen C. On the topological surface states of the intrinsic magnetic topological insulator Mn-Bi-Te family. Natl Sci Rev 2024; 11:nwad066. [PMID: 38213518 PMCID: PMC10776371 DOI: 10.1093/nsr/nwad066] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/12/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2024] Open
Abstract
We review recent progress in the electronic structure study of intrinsic magnetic topological insulators (MnBi2Te4) · (Bi2Te3)n ([Formula: see text]) family. Specifically, we focus on the ubiquitously (nearly) gapless behavior of the topological Dirac surface state observed by photoemission spectroscopy, even though a large Dirac gap is expected because of surface ferromagnetic order. The dichotomy between experiment and theory concerning this gap behavior is perhaps the most critical and puzzling question in this frontier. We discuss various proposals accounting for the lack of magnetic effect on the topological Dirac surface state, which are mainly categorized into two pictures, magnetic reconfiguration and topological surface state redistribution. Band engineering towards opening a magnetic gap of topological surface states provides great opportunities to realize quantized topological transport and axion electrodynamics at higher temperatures.
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Affiliation(s)
- Yuan Wang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Xiao-Ming Ma
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Zhanyang Hao
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Yongqing Cai
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Hongtao Rong
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Fayuan Zhang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Weizhao Chen
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chengcheng Zhang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Junhao Lin
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Yue Zhao
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chang Liu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Qihang Liu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chaoyu Chen
- Shenzhen Institute for Quantum Science and Engineering (SIQSE) and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
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16
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Xu R, Xu L, Liu Z, Yang L, Chen Y. ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi 2+2nTe 4+3n family. Natl Sci Rev 2024; 11:nwad313. [PMID: 38327664 PMCID: PMC10849349 DOI: 10.1093/nsr/nwad313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/14/2023] [Accepted: 11/19/2023] [Indexed: 02/09/2024] Open
Abstract
In the past 5 years, there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n (where n = 0, 1, 2 …). In particular, exfoliated thin films of MnBi2Te4 have led to numerous experimental breakthroughs, such as the quantum anomalous Hall effect, axion insulator phase and high-Chern number quantum Hall effect without Landau levels. However, despite extensive efforts, the energy gap of the topological surface states due to exchange magnetic coupling, which is a key feature of the characteristic band structure of the system, remains experimentally elusive. The electronic structure measured by using angle-resolved photoemission (ARPES) shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements, making it challenging to understand the transport results based on the electronic structure. This paper reviews the measurements of the band structure of MnBi2+2nTe4+3n magnetic topological insulators using ARPES, focusing on the evolution of their electronic structures with temperature, surface and bulk doping and film thickness. The aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3n compounds and explore possible control of their topological properties.
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Affiliation(s)
- Runzhe Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lixuan Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
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17
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Hu C, Qian T, Ni N. Recent progress in MnBi 2nTe 3n+1 intrinsic magnetic topological insulators: crystal growth, magnetism and chemical disorder. Natl Sci Rev 2024; 11:nwad282. [PMID: 38213523 PMCID: PMC10776370 DOI: 10.1093/nsr/nwad282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/19/2023] [Accepted: 09/06/2023] [Indexed: 01/13/2024] Open
Abstract
The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators, etc. To date, the MnBi2nTe3n+1 family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.
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Affiliation(s)
- Chaowei Hu
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Tiema Qian
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Ni Ni
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
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18
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Liu S, Yu JX, Zhang E, Li Z, Sun Q, Zhang Y, Cao L, Li L, Zhao M, Leng P, Cao X, Li A, Zou J, Kou X, Zang J, Xiu F. Gate-tunable Intrinsic Anomalous Hall Effect in Epitaxial MnBi 2Te 4 Films. NANO LETTERS 2024; 24:16-25. [PMID: 38109350 DOI: 10.1021/acs.nanolett.3c02926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
The anomalous Hall effect (AHE) is an important transport signature revealing topological properties of magnetic materials and their spin textures. Recently, MnBi2Te4 has been demonstrated to be an intrinsic magnetic topological insulator. However, the origin of its intriguing AHE behaviors remains elusive. Here, we demonstrate the Berry curvature-dominated intrinsic AHE in wafer-scale MnBi2Te4 films. By applying back-gate voltages, we observe an ambipolar conduction and n-p transition in ∼7-layer MnBi2Te4, where a quadratic relation between the AHE resistance and longitudinal resistance suggests its intrinsic AHE nature. In particular, for ∼3-layer MnBi2Te4, the AHE sign can be tuned from pristine negative to positive. First-principles calculations unveil that such an AHE reversal originated from the competing Berry curvature between oppositely polarized spin-minority-dominated surface states and spin-majority-dominated inner bands. Our results shed light on the underlying physical mechanism of the intrinsic AHE and provide new perspectives for the unconventional sign-tunable AHE.
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Affiliation(s)
- Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Jie-Xiang Yu
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Qiang Sun
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Yong Zhang
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Liwei Cao
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Lun Li
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Minhao Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Pengliang Leng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Xiangyu Cao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Ang Li
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, New Hampshire 03824, United States
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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19
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Rastogi G, Mohapatra A, Mishra P, Mandal S, Kulkarni R, Ganesan R, Thamizhavel A, Anil Kumar PS. Crossover from gapped-to-gapless Dirac surface states in magnetic topological insulator MnBi 2Te 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:085703. [PMID: 37883988 DOI: 10.1088/1361-648x/ad0765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/26/2023] [Indexed: 10/28/2023]
Abstract
Intrinsic magnetic topological insulators (MTIs) host exotic topological phases such as quantized anomalous Hall insulating phase, arising due to the large magnetic exchange gap. However, the interplay of magnetism and topology in these systems in different temperature regimes remains elusive. In this work, we present the logarithmic temperature-dependence of conductivity for sub-100 nm thick exfoliated flakes of MTI MnBi2Te4in the presence of out-of-plane magnetic fields and extracted the linear slope,κ. We observed a characteristic change,Δκ∼-0.5in the low-temperature regime, indicating the gapped Dirac surface state according to Lu-Shen theory. We also report the recovery of topological properties in the system via the weak-antilocalization effect in the vicinity of antiferromagnetic to paramagnetic transition and in the paramagnetic regime. Hikami-Larkin-Nagaoka analysis suggested the presence of topological surface states. Therefore, our study helps in understanding how intrinsic magnetism masks topological properties in an MTI as long as magnetic ordering persists.
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Affiliation(s)
- Gagan Rastogi
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Abhinab Mohapatra
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Pramita Mishra
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Shoubhik Mandal
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Ruta Kulkarni
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - R Ganesan
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - A Thamizhavel
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - P S Anil Kumar
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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20
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Matetskiy AV, Milotti V, Sheverdyaeva PM, Moras P, Carbone C, Mihalyuk AN. Interplay between magnetic order and electronic band structure in ultrathin GdGe 2 metalloxene films. NANOSCALE 2023; 15:16080-16088. [PMID: 37750836 DOI: 10.1039/d3nr03398h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Dimensionality can strongly influence the magnetic structure of solid systems. Here, we predict theoretically and confirm experimentally that the antiferromagnetic (AFM) ground state of bulk gadolinium germanide metalloxene, which has a quasi-layered defective GdGe2 structure, is preserved in the ultrathin film limit. Ab initio calculations demonstrate that ultrathin GdGe2 films present in-plane intra-layer ferromagnetic coupling and AFM inter-layer coupling in the ground state. Angle-resolved photoemission spectroscopy finds the AFM-induced band splitting expected for the 2 and 3 GdGe2 trilayer (TL) films, which disappear above the Néel temperature. The comparative analysis of isostructural ultrathin DyGe2 and GdSi2 films confirms the magnetic origin of the observed band splitting. These findings are in contrast with the recent report of ferromagnetism in ultrathin metalloxene films, which we ascribe to the presence of uncompensated magnetic moments.
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Affiliation(s)
- Andrey V Matetskiy
- Istituto di Struttura della Materia-CNR (ISM-CNR), Strada Statale 14 km 163.5, 34149, Trieste, Italy.
- Institute of Automation and Control Processes FEB RAS, 690041 Vladivostok, Russia.
| | - Valeria Milotti
- Istituto di Struttura della Materia-CNR (ISM-CNR), Strada Statale 14 km 163.5, 34149, Trieste, Italy.
| | - Polina M Sheverdyaeva
- Istituto di Struttura della Materia-CNR (ISM-CNR), Strada Statale 14 km 163.5, 34149, Trieste, Italy.
| | - Paolo Moras
- Istituto di Struttura della Materia-CNR (ISM-CNR), Strada Statale 14 km 163.5, 34149, Trieste, Italy.
| | - Carlo Carbone
- Istituto di Struttura della Materia-CNR (ISM-CNR), Strada Statale 14 km 163.5, 34149, Trieste, Italy.
| | - Alexey N Mihalyuk
- Institute of Automation and Control Processes FEB RAS, 690041 Vladivostok, Russia.
- Institute of High Technologies and Advanced Materials, Far Eastern Federal University, 690950 Vladivostok, Russia
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21
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Luo J, Tong Q, Jiang Z, Bai H, Wu J, Liu X, Xie S, Ge H, Zhao Y, Liu Y, Hong M, Shen D, Zhang Q, Liu W, Tang X. Exploring the Epitaxial Growth Kinetics and Anomalous Hall Effect in Magnetic Topological Insulator MnBi 2Te 4 Films. ACS NANO 2023; 17:19022-19032. [PMID: 37732876 DOI: 10.1021/acsnano.3c04626] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
The discovery of MnBi2Te4-based intrinsic magnetic topological insulators has fueled tremendous interest in condensed matter physics, owing to their potential as an ideal platform for exploring the quantum anomalous Hall effect and other magnetism-topology interactions. However, the fabrication of single-phase MnBi2Te4 films remains a common challenge in the research field. Herein, we present an effective and simple approach for fabricating high-quality, near-stoichiometric MnBi2Te4 films by directly matching the growth rates of intermediate Bi2Te3 and MnTe. Through systematic experimental studies and thermodynamic calculations, we demonstrate that binary phases of Bi2Te3 and MnTe are easily formed during film growth, and the reaction of Bi2Te3 + MnTe → MnBi2Te4 represents the rate-limiting step among all possible reaction paths, which could result in the presence of Bi2Te3 and MnTe impurity phases in the grown MnBi2Te4 films. Moreover, Bi2Te3 and MnTe impurities introduce negative and positive anomalous Hall (AH) components, respectively, in the AH signals of MnBi2Te4 films. Our work suggests that further manipulation of growth parameters should be the essential route for fabricating phase-pure MnBi2Te4 films.
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Affiliation(s)
- Jiangfan Luo
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Qiwei Tong
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhicheng Jiang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai 200050, China
| | - Hui Bai
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Jinsong Wu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaolin Liu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Sen Xie
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Haoran Ge
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Yan Zhao
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
- The Institute of Technological Sciences, Wuhan University, Wuhan 430070, China
| | - Yong Liu
- Department of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Min Hong
- Centre for Future Materials, and School of Engineering, University of Southern Queensland, Springfield, Queensland 4300, Australia
| | - Dawei Shen
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Qingjie Zhang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Wei Liu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
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22
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Xiang ZC, Huang K, Zhang YR, Liu T, Shi YH, Deng CL, Liu T, Li H, Liang GH, Mei ZY, Yu H, Xue G, Tian Y, Song X, Liu ZB, Xu K, Zheng D, Nori F, Fan H. Simulating Chern insulators on a superconducting quantum processor. Nat Commun 2023; 14:5433. [PMID: 37669968 PMCID: PMC10480218 DOI: 10.1038/s41467-023-41230-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 08/23/2023] [Indexed: 09/07/2023] Open
Abstract
The quantum Hall effect, fundamental in modern condensed matter physics, continuously inspires new theories and predicts emergent phases of matter. Here we experimentally demonstrate three types of Chern insulators with synthetic dimensions on a programable 30-qubit-ladder superconducting processor. We directly measure the band structures of the 2D Chern insulator along synthetic dimensions with various configurations of Aubry-André-Harper chains and observe dynamical localisation of edge excitations. With these two signatures of topology, our experiments implement the bulk-edge correspondence in the synthetic 2D Chern insulator. Moreover, we simulate two different bilayer Chern insulators on the ladder-type superconducting processor. With the same and opposite periodically modulated on-site potentials for two coupled chains, we simulate topologically nontrivial edge states with zero Hall conductivity and a Chern insulator with higher Chern numbers, respectively. Our work shows the potential of using superconducting qubits for investigating different intriguing topological phases of quantum matter.
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Affiliation(s)
- Zhong-Cheng Xiang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Kaixuan Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300457, China
| | - Yu-Ran Zhang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, 510640, China
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan
- Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Tao Liu
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, 510640, China
| | - Yun-Hao Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Cheng-Lin Deng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Tong Liu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hao Li
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Gui-Han Liang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zheng-Yang Mei
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Haifeng Yu
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Guangming Xue
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Ye Tian
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiaohui Song
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhi-Bo Liu
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300457, China
| | - Kai Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
| | - Dongning Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Physics Department, University of Michigan, Ann Arbor, MI, 48109-1040, USA.
| | - Heng Fan
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
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23
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Chong SK, Lei C, Lee SH, Jaroszynski J, Mao Z, MacDonald AH, Wang KL. Anomalous Landau quantization in intrinsic magnetic topological insulators. Nat Commun 2023; 14:4805. [PMID: 37558682 PMCID: PMC10412595 DOI: 10.1038/s41467-023-40383-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 07/21/2023] [Indexed: 08/11/2023] Open
Abstract
The intrinsic magnetic topological insulator, Mn(Bi1-xSbx)2Te4, has been identified as a Weyl semimetal with a single pair of Weyl nodes in its spin-aligned strong-field configuration. A direct consequence of the Weyl state is the layer dependent Chern number, [Formula: see text]. Previous reports in MnBi2Te4 thin films have shown higher [Formula: see text] states either by increasing the film thickness or controlling the chemical potential. A clear picture of the higher Chern states is still lacking as data interpretation is further complicated by the emergence of surface-band Landau levels under magnetic fields. Here, we report a tunable layer-dependent [Formula: see text] = 1 state with Sb substitution by performing a detailed analysis of the quantization states in Mn(Bi1-xSbx)2Te4 dual-gated devices-consistent with calculations of the bulk Weyl point separation in the doped thin films. The observed Hall quantization plateaus for our thicker Mn(Bi1-xSbx)2Te4 films under strong magnetic fields can be interpreted by a theory of surface and bulk spin-polarised Landau level spectra in thin film magnetic topological insulators.
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Affiliation(s)
- Su Kong Chong
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA.
| | - Chao Lei
- Department of Physics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Seng Huat Lee
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Jan Jaroszynski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Zhiqiang Mao
- 2D Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Allan H MacDonald
- Department of Physics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA.
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24
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Li Y, Liu C, Wang Y, Lian Z, Li S, Li H, Wu Y, Lu HZ, Zhang J, Wang Y. Giant nonlocal edge conduction in the axion insulator state of MnBi 2Te 4. Sci Bull (Beijing) 2023:S2095-9273(23)00318-3. [PMID: 37268443 DOI: 10.1016/j.scib.2023.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 04/28/2023] [Accepted: 05/04/2023] [Indexed: 06/04/2023]
Abstract
The recently discovered antiferromagnetic (AFM) topological insulator (TI) MnBi2Te4 represents a versatile material platform for exploring exotic topological quantum phenomena in nanoscale devices. It has been proposed that even-septuple-layer (even-SL) MnBi2Te4 can host helical hinge currents with unique nonlocal behavior, but experimental confirmation is still lacking. In this work, we report transport studies of exfoliated MnBi2Te4 flakes with varied thicknesses down to the few-nanometer regime. We observe giant nonlocal transport signals in even-SL devices when the system is in the axion insulator state but vanishingly small nonlocal signal in the odd-SL devices at the same magnetic field range. In conjunction with theoretical calculations, we demonstrate that the nonlocal transport is via the helical edge currents mainly distributed at the hinges between the side and top/bottom surfaces. The helical edge currents in the axion insulator state may find unique applications in topological quantum devices.
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Affiliation(s)
- Yaoxin Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Chang Liu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China; Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China; Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China
| | - Yongchao Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zichen Lian
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Shuai Li
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China; Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China; International Quantum Academy, Shenzhen 518048, China
| | - Hao Li
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yang Wu
- Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing 100084, China; College of Science, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China; Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen 518045, China; International Quantum Academy, Shenzhen 518048, China.
| | - Jinsong Zhang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Hefei National Laboratory, Hefei 230088, China.
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; New Cornerstone Science Laboratory, Frontier Science Center for Quantum Information, Beijing 100084, China; Hefei National Laboratory, Hefei 230088, China.
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25
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Li X, Xu X, Zhou H, Jia H, Wang E, Fu H, Sun JT, Meng S. Tunable Topological States in Stacked Chern Insulator Bilayers. NANO LETTERS 2023; 23:2839-2845. [PMID: 36975717 DOI: 10.1021/acs.nanolett.3c00154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The emergence of intrinsic quantum anomalous Hall (QAH) insulators with a long-range ferromagnetic (FM) order triggers unprecedented prosperity for combining topology and magnetism in low dimensions. Built upon atom-thin Chern insulator monolayer MnBr3, we propose that the topologically nontrivial electronic states can be systematically tuned by inherent magnetic orders and external electric/optical fields in stacked Chern insulator bilayers. The FM bilayer illustrates a high-Chern-number QAH state characterized by both quantized Hall plateaus and specific magneto-optical Kerr angles. In antiferromagnetic bilayers, Berry curvature singularity induced by electrostatic fields or lasers emerges, which further leads to a novel implementation of the layer Hall effect depending on the chirality of irradiated circularly polarized light. These results demonstrate that abundant tunable topological properties can be achieved in stacked Chern insulator bilayers, thereby suggesting a universal routine to modulate d-orbital-dominated topological Dirac fermions.
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Affiliation(s)
- Xuanyi Li
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Xifan Xu
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, China
- Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing University, Chongqing 401331, China
| | - Hui Zhou
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Huaxian Jia
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - En Wang
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Huixia Fu
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, China
- Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing University, Chongqing 401331, China
| | - Jia-Tao Sun
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Sheng Meng
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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26
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Tan H, Yan B. Distinct Magnetic Gaps between Antiferromagnetic and Ferromagnetic Orders Driven by Surface Defects in the Topological Magnet MnBi_{2}Te_{4}. PHYSICAL REVIEW LETTERS 2023; 130:126702. [PMID: 37027867 DOI: 10.1103/physrevlett.130.126702] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 03/03/2023] [Indexed: 06/09/2023]
Abstract
Many experiments observed a metallic behavior at zero magnetic fields (antiferromagnetic phase, AFM) in MnBi_{2}Te_{4} thin film transport, which coincides with gapless surface states observed by angle-resolved photoemission spectroscopy, while it can become a Chern insulator at field larger than 6 T (ferromagnetic phase, FM). Thus, the zero-field surface magnetism was once speculated to be different from the bulk AFM phase. However, recent magnetic force microscopy refutes this assumption by detecting persistent AFM order on the surface. In this Letter, we propose a mechanism related to surface defects that can rationalize these contradicting observations in different experiments. We find that co-antisites (exchanging Mn and Bi atoms in the surface van der Waals layer) can strongly suppress the magnetic gap down to several meV in the AFM phase without violating the magnetic order but preserve the magnetic gap in the FM phase. The different gap sizes between AFM and FM phases are caused by the exchange interaction cancellation or collaboration of the top two van der Waals layers manifested by defect-induced surface charge redistribution among the top two van der Waals layers. This theory can be validated by the position- and field-dependent gap in future surface spectroscopy measurements. Our work suggests suppressing related defects in samples to realize the quantum anomalous Hall insulator or axion insulator at zero fields.
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Affiliation(s)
- Hengxin Tan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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27
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Cui J, Lei B, Shi M, Xiang Z, Wu T, Chen X. Layer-Dependent Magnetic Structure and Anomalous Hall Effect in the Magnetic Topological Insulator MnBi 4Te 7. NANO LETTERS 2023; 23:1652-1658. [PMID: 36790199 DOI: 10.1021/acs.nanolett.2c03773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The intrinsic antiferromagnetic topological insulator (TI) MnBi4Te7 provides a capacious playground for the realization of topological quantum phenomena, such as the axion insulator states and quantum anomalous Hall (QAH) effect. In addition to nontrivial band topology, magnetism is another necessary ingredient for realizing these quantum phenomena. Here, we investigate signatures of thickness-dependent magnetism in exfoliated MnBi4Te7 thin flakes. We observe an obvious odd-even layer-number effect in few-layer MnBi4Te7. Noticeably, we show that in monolayer MnBi4Te7 the anomalous Hall effect exhibits a sign reversal. Compared with the case of MnBi2Te4, interlayer antiferromagnetic exchange coupling, which is essential for the realization of the QAH effect, is greatly suppressed in MnBi4Te7. The demonstration of thickness-dependent magnetic properties is helpful to further explore the topological quantum phenomena in MnBi4Te7.
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Affiliation(s)
| | | | | | | | - Tao Wu
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xianhui Chen
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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28
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Ying Z, Chen B, Li C, Wei B, Dai Z, Guo F, Pan D, Zhang H, Wu D, Wang X, Zhang S, Fei F, Song F. Large Exchange Bias Effect and Coverage-Dependent Interfacial Coupling in CrI 3/MnBi 2Te 4 van der Waals Heterostructures. NANO LETTERS 2023; 23:765-771. [PMID: 36542799 DOI: 10.1021/acs.nanolett.2c02882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Igniting interface magnetic ordering of magnetic topological insulators by building a van der Waals heterostructure can help to reveal novel quantum states and design functional devices. Here, we observe an interesting exchange bias effect, indicating successful interfacial magnetic coupling, in CrI3/MnBi2Te4 ferromagnetic insulator/antiferromagnetic topological insulator (FMI/AFM-TI) heterostructure devices. The devices originally exhibit a negative exchange bias field, which decays with increasing temperature and is unaffected by the back-gate voltage. When we change the device configuration to be half-covered by CrI3, the exchange bias becomes positive with a very large exchange bias field exceeding 300 mT. Such sensitive manipulation is explained by the competition between the FM and AFM coupling at the interface of CrI3 and MnBi2Te4, pointing to coverage-dependent interfacial magnetic interactions. Our work will facilitate the development of topological and antiferromagnetic devices.
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Affiliation(s)
- Zhe Ying
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Chunfeng Li
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Boyuan Wei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Zheng Dai
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Fengyi Guo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Danfeng Pan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
- Microfabrication and Integration Technology Center, Nanjing University, Nanjing 210093, China
| | - Haijun Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Di Wu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Xuefeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
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29
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Xu Z, Duan W, Xu Y. Controllable Chirality and Band Gap of Quantum Anomalous Hall Insulators. NANO LETTERS 2023; 23:305-311. [PMID: 36537751 DOI: 10.1021/acs.nanolett.2c04369] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Finding guiding principles to optimize properties of quantum anomalous Hall (QAH) insulators is of pivotal importance to fundamental science and applications. Here, we build a first-principles QAH material database of chirality and band gap, explore microscopic mechanisms determining the QAH material properties, and obtain a general physical picture that can help researchers comprehensively understand the QAH data. Our results reveal that the usually neglected Coulomb exchange is unexpectedly strong in a large class of QAH materials, which is the key to resolve experimental puzzles. Moreover, we identify simple indicators for property evaluation and suggest material design strategies to control QAH chirality and gap by tuning cooperative or competing contributions via magnetic codoping, heterostructuring, spin-orbit proximity, etc. The work is valuable to future research of magnetic topological physics and materials.
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Affiliation(s)
- Zhiming Xu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
| | - Wenhui Duan
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong518057, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing100084, China
- Institute for Advanced Study, Tsinghua University, Beijing100084, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Yong Xu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong518057, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing100084, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama351-0198, Japan
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30
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Fonseca J, Diederich GM, Ovchinnikov D, Cai J, Wang C, Yan J, Xiao D, Xu X. Anomalous Second Harmonic Generation from Atomically Thin MnBi 2Te 4. NANO LETTERS 2022; 22:10134-10139. [PMID: 36475690 DOI: 10.1021/acs.nanolett.2c04010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
MnBi2Te4 is a van der Waals topological insulator with intrinsic intralayer ferromagnetic exchange and A-type antiferromagnetic interlayer coupling. Theoretically, it belongs to a class of structurally centrosymmetric crystals whose layered antiferromagnetic order breaks inversion symmetry for even layer numbers, making optical second harmonic generation (SHG) an ideal probe of the coupling between the crystal and magnetic structures. Here, we perform magnetic field and temperature-dependent SHG measurements on MnBi2Te4 flakes ranging from bulk to monolayer thickness. We find that the dominant SHG signal from MnBi2Te4 is unexpectedly unrelated to both magnetic state and layer number. We suggest that surface SHG is the likely source of the observed strong SHG, whose symmetry matches that of the MnBi2Te4-vacuum interface. Our results highlight the importance of considering the surface contribution to inversion symmetry-breaking in van der Waals centrosymmetric magnets.
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Affiliation(s)
- Jordan Fonseca
- Department of Physics, University of Washington, Seattle, Washington98195, United States
| | - Geoffrey M Diederich
- Department of Physics, University of Washington, Seattle, Washington98195, United States
- Intelligence Community Postdoctoral Research Fellowship Program, University of Washington, Seattle, Washington98195, United States
| | - Dmitry Ovchinnikov
- Department of Physics, University of Washington, Seattle, Washington98195, United States
| | - Jiaqi Cai
- Department of Physics, University of Washington, Seattle, Washington98195, United States
| | - Chong Wang
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington98195, United States
| | - Jiaqiang Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Di Xiao
- Department of Physics, University of Washington, Seattle, Washington98195, United States
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington98195, United States
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington98195, United States
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington98195, United States
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31
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Vyazovskaya AY, Petrov EK, Koroteev YM, Bosnar M, Silkin IV, Chulkov EV, Otrokov MM. Superlattices of Gadolinium and Bismuth Based Thallium Dichalcogenides as Potential Magnetic Topological Insulators. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:38. [PMID: 36615948 PMCID: PMC9824305 DOI: 10.3390/nano13010038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/17/2022] [Accepted: 12/17/2022] [Indexed: 06/17/2023]
Abstract
Using relativistic spin-polarized density functional theory calculations we investigate magnetism, electronic structure and topology of the ternary thallium gadolinium dichalcogenides TlGdZ2 (Z= Se and Te) as well as superlattices on their basis. We find TlGdZ2 to have an antiferromagnetic exchange coupling both within and between the Gd layers, which leads to frustration and a complex magnetic structure. The electronic structure calculations reveal both TlGdSe2 and TlGdTe2 to be topologically trivial semiconductors. However, as we show further, a three-dimensional (3D) magnetic topological insulator (TI) state can potentially be achieved by constructing superlattices of the TlGdZ2/(TlBiZ2)n type, in which structural units of TlGdZ2 are alternated with those of the isomorphic TlBiZ2 compounds, known to be non-magnetic 3D TIs. Our results suggest a new approach for achieving 3D magnetic TI phases in such superlattices which is applicable to a large family of thallium rare-earth dichalcogenides and is expected to yield a fertile and tunable playground for exotic topological physics.
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Affiliation(s)
- Alexandra Yu. Vyazovskaya
- Laboratory of Nanostructured Surfaces and Coatings, Tomsk State University, Tomsk 634050, Russia
- Laboratory of Electronic and Spin Structure of Nanosystems, St. Petersburg State University, St. Petersburg 198504, Russia
| | - Evgeniy K. Petrov
- Laboratory of Nanostructured Surfaces and Coatings, Tomsk State University, Tomsk 634050, Russia
- Laboratory of Electronic and Spin Structure of Nanosystems, St. Petersburg State University, St. Petersburg 198504, Russia
| | - Yury M. Koroteev
- Laboratory of Electronic and Spin Structure of Nanosystems, St. Petersburg State University, St. Petersburg 198504, Russia
- Institute of Strength Physics and Materials Science, Tomsk 634021, Russia
| | - Mihovil Bosnar
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco UPV/EHU, 20080 Donostia-San Sebastián, Basque Country, Spain
| | - Igor V. Silkin
- Laboratory of Nanostructured Surfaces and Coatings, Tomsk State University, Tomsk 634050, Russia
| | - Evgueni V. Chulkov
- Laboratory of Electronic and Spin Structure of Nanosystems, St. Petersburg State University, St. Petersburg 198504, Russia
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco UPV/EHU, 20080 Donostia-San Sebastián, Basque Country, Spain
| | - Mikhail M. Otrokov
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country, Spain
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32
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Lei Y, Zhang T, Lin YC, Granzier-Nakajima T, Bepete G, Kowalczyk DA, Lin Z, Zhou D, Schranghamer TF, Dodda A, Sebastian A, Chen Y, Liu Y, Pourtois G, Kempa TJ, Schuler B, Edmonds MT, Quek SY, Wurstbauer U, Wu SM, Glavin NR, Das S, Dash SP, Redwing JM, Robinson JA, Terrones M. Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices. ACS NANOSCIENCE AU 2022; 2:450-485. [PMID: 36573124 PMCID: PMC9782807 DOI: 10.1021/acsnanoscienceau.2c00017] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 12/30/2022]
Abstract
Since the isolation of graphene in 2004, two-dimensional (2D) materials research has rapidly evolved into an entire subdiscipline in the physical sciences with a wide range of emergent applications. The unique 2D structure offers an open canvas to tailor and functionalize 2D materials through layer number, defects, morphology, moiré pattern, strain, and other control knobs. Through this review, we aim to highlight the most recent discoveries in the following topics: theory-guided synthesis for enhanced control of 2D morphologies, quality, yield, as well as insights toward novel 2D materials; defect engineering to control and understand the role of various defects, including in situ and ex situ methods; and properties and applications that are related to moiré engineering, strain engineering, and artificial intelligence. Finally, we also provide our perspective on the challenges and opportunities in this fascinating field.
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Affiliation(s)
- Yu Lei
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Institute
of Materials Research, Tsinghua Shenzhen
International Graduate School, Shenzhen, Guangdong 518055, China,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tianyi Zhang
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yu-Chuan Lin
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tomotaroh Granzier-Nakajima
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - George Bepete
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Dorota A. Kowalczyk
- Department
of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, Lodz 90-236, Poland
| | - Zhong Lin
- Department
of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Da Zhou
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Thomas F. Schranghamer
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Akhil Dodda
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Amritanand Sebastian
- Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Yifeng Chen
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Yuanyue Liu
- Texas
Materials Institute and Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Thomas J. Kempa
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21287, United States
| | - Bruno Schuler
- nanotech@surfaces
Laboratory, Empa − Swiss Federal
Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Mark T. Edmonds
- School
of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
| | - Su Ying Quek
- Department
of Materials Science and Engineering, National
University of Singapore, 9 Engineering Drive, Singapore 117456, Singapore
| | - Ursula Wurstbauer
- Institute
of Physics, University of Münster, Wilhelm-Klemm-Str. 10, Münster 48149, Germany
| | - Stephen M. Wu
- Department
of Electrical and Computer Engineering & Department of Physics
and Astronomy, University of Rochester, Rochester, New York 14627, United States
| | - Nicholas R. Glavin
- Air
Force
Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Dayton, Ohio 45433, United States
| | - Saptarshi Das
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Engineering Science and Mechanics, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Saroj Prasad Dash
- Department
of Microtechnology and Nanoscience, Chalmers
University of Technology, Göteborg SE-412 96, Sweden
| | - Joan M. Redwing
- Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joshua A. Robinson
- Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,
| | - Mauricio Terrones
- Department
of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for Atomically Thin Multifunctional Coatings, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Center
for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Material Science and Engineering, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States,Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States,Research
Initiative for Supra-Materials and Global Aqua Innovation Center, Shinshu University, 4-17-1Wakasato, Nagano 380-8553, Japan,
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33
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Wu Y, Li J, Liu Y. Two-dimensional chalcogenide-based ferromagnetic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:083002. [PMID: 36540916 DOI: 10.1088/1361-648x/acaa7e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) magnetic materials draw an enormous amount of attention due to their novel physical properties and potential spintronics device applications. Room-temperature ferromagnetic (FM) semiconductors have long been pursued in 2D magnetic materials, which show a long range magnetic order down to atomic-layer thickness. The intrinsic ferromagnetism has been predicted in a series of 2D materials and verified in experiments and the magnetism can be modulated by multiple physical fields, exhibiting promising application prospects. In this review, we overview several types of 2D chalcogenide-based FM semiconductors discovered in recent years. We summary and compare their basic physical properties, including the crystal structures, electronic structures, and mechanical stability. The 2D magnetism can be described by several physical models. We also focus on the recent progresses about theoretical prediction of FM semiconductors and experimental observation of external-field regulation. Most of investigations have shown that 2D chalcogenide-based FM semiconductors have relatively high Curie temperature (Tc) and structural stability. These materials are promising to realize the room-temperature ferromagnetism in atomic-layer thickness, which is significant to design spintronics devices.
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Affiliation(s)
- Yanling Wu
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
| | - Jun Li
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
| | - Yong Liu
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
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34
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Xu X, Yang S, Wang H, Guzman R, Gao Y, Zhu Y, Peng Y, Zang Z, Xi M, Tian S, Li Y, Lei H, Luo Z, Yang J, Wang Y, Xia T, Zhou W, Huang Y, Ye Y. Ferromagnetic-antiferromagnetic coexisting ground state and exchange bias effects in MnBi 4Te 7 and MnBi 6Te 10. Nat Commun 2022; 13:7646. [PMID: 36496444 PMCID: PMC9741634 DOI: 10.1038/s41467-022-35184-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Natural superlattice structures MnBi2Te4(Bi2Te3)n (n = 1, 2, ...), in which magnetic MnBi2Te4 layers are separated by nonmagnetic Bi2Te3 layers, hold band topology, magnetism and reduced interlayer coupling, providing a promising platform for the realization of exotic topological quantum states. However, their magnetism in the two-dimensional limit, which is crucial for further exploration of quantum phenomena, remains elusive. Here, complex ferromagnetic-antiferromagnetic coexisting ground states that persist down to the 2-septuple layers limit are observed and comprehensively investigated in MnBi4Te7 (n = 1) and MnBi6Te10 (n = 2). The ubiquitous Mn-Bi site mixing modifies or even changes the sign of the subtle interlayer magnetic interactions, yielding a spatially inhomogeneous interlayer coupling. Further, a tunable exchange bias effect, arising from the coupling between the ferromagnetic and antiferromagnetic components in the ground state, is observed in MnBi2Te4(Bi2Te3)n (n = 1, 2), which provides design principles and material platforms for future spintronic devices. Our work highlights a new approach toward the fine-tuning of magnetism and paves the way for further study of quantum phenomena in MnBi2Te4(Bi2Te3)n (n = 1, 2) as well as their magnetic applications.
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Affiliation(s)
- Xiaolong Xu
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China ,grid.43555.320000 0000 8841 6246School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081 China ,grid.495569.2Collaborative Innovation Center of Quantum Matter, Beijing, 100871 China
| | - Shiqi Yang
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871 China
| | - Huan Wang
- grid.24539.390000 0004 0368 8103Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872 China
| | - Roger Guzman
- grid.410726.60000 0004 1797 8419School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yuchen Gao
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Yaozheng Zhu
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Yuxuan Peng
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Zhihao Zang
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Ming Xi
- grid.24539.390000 0004 0368 8103Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872 China
| | - Shangjie Tian
- grid.24539.390000 0004 0368 8103Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872 China
| | - Yanping Li
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Hechang Lei
- grid.24539.390000 0004 0368 8103Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872 China ,grid.24539.390000 0004 0368 8103Laboratory for Neutron Scattering, Department of Physics, Renmin University of China, Beijing, 100872 China
| | - Zhaochu Luo
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Jinbo Yang
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China
| | - Yeliang Wang
- grid.43555.320000 0000 8841 6246School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081 China
| | - Tianlong Xia
- grid.24539.390000 0004 0368 8103Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872 China
| | - Wu Zhou
- grid.410726.60000 0004 1797 8419School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.410726.60000 0004 1797 8419CAS Centre for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yuan Huang
- grid.43555.320000 0000 8841 6246School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, 100081 China ,grid.43555.320000 0000 8841 6246Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing, 100081 China
| | - Yu Ye
- grid.11135.370000 0001 2256 9319State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871 China ,grid.495569.2Collaborative Innovation Center of Quantum Matter, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319Yangtze Delta Institute of Optoelectronics, Peking University, Nantong, 226010 Jiangsu China
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Lv Q, Fu PH, Zhuang Q, Yu XL, Wu J. Two-dimensional antiferromagnetic nodal-line semimetal and quantum anomalous Hall state in the van der Waals heterostructure germanene/Mn 2S 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:505702. [PMID: 36261049 DOI: 10.1088/1361-648x/ac9bb9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
Materials with interactions between the topology and magnetism are triggering increasing interest. We constructed a two-dimensional (2D) van der Waals heterostructure germanene/Mn2S2, where the germanene is a quantum spin Hall insulator and Mn2S2provides antiferromagnetic (AFM) interactions. In this structure, a 2D AFM nodal-line semimetal (NLSM) phase is expected without the spin-orbit coupling (SOC), which is of a high density of states around the Fermi level. The band touching rings originate from the intersection between different spin components ofporbitals of germanene. This result provides a possible 2D realization of NLSMs, which are usually realized in three-dimensional systems. When the SOC is present, a quantum anomalous Hall (QAH) state emerges with the annihilation of the band-touching rings. The nontrivial topology is determined by calculating the Chern number and Wannier charge centers. This provides an alternative platform to realize QAH states. These results could also provide the possibility of further understanding the topological states in NLSM and electronic applications.
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Affiliation(s)
- Qianqian Lv
- Department of Physics, Harbin Institute of Technology, Harbin 150001, People's Republic of China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Pei-Hao Fu
- Department of Physics, Harbin Institute of Technology, Harbin 150001, People's Republic of China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Quan Zhuang
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College of Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao 028000, People's Republic of China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- International Quantum Academy, Shenzhen 518048, People's Republic of China
| | - Jiansheng Wu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- International Quantum Academy, Shenzhen 518048, People's Republic of China
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Chang ZW, Hao WC, Liu X. Topological defects in Haldane model and higher Chern numbers in monolayer graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:485502. [PMID: 36218906 DOI: 10.1088/1361-648x/ac98fc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
We consider the Haldane model, a two-band model in monolayer graphene with non-trivial Chern numbers. Two types of topological defects, monopoles and merons, are derived from the model: (a) the monopole defects occur at the Dirac points, where the system experiences a topological transition and the Chern numberCtakes an indeterminate value. The sign-change of the mass term after this transition indicates different topological states labeled by differentCnumbers; (b) the meron defects occur as per a varying mass term. Summing up the topological charges of the merons leads to theCevaluation for the energy bands of an insulating bulk, and the result we obtain is in full agreement to the past literature. Furthermore, in this paper we propose a high-Cmodel through studying the limitation behavior of the Hamiltonian vector in the neighborhood of the topological defects. It is discovered that two conducting states may arise form the edges, where the lower band of the insulating bulk carries a higher Chern number,C=±2.
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Affiliation(s)
- Zhi-Wen Chang
- Institute of Theoretical Physics, Faculty of Sciences, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Wei-Chang Hao
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
| | - Xin Liu
- Institute of Theoretical Physics, Faculty of Sciences, Beijing University of Technology, Beijing 100124, People's Republic of China
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Visualizing the interplay of Dirac mass gap and magnetism at nanoscale in intrinsic magnetic topological insulators. Proc Natl Acad Sci U S A 2022; 119:e2207681119. [PMID: 36215491 PMCID: PMC9586289 DOI: 10.1073/pnas.2207681119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In intrinsic magnetic topological insulators, Dirac surface-state gaps are prerequisites for quantum anomalous Hall and axion insulating states. Unambiguous experimental identification of these gaps has proved to be a challenge, however. Here, we use molecular beam epitaxy to grow intrinsic MnBi2Te4 thin films. Using scanning tunneling microscopy/spectroscopy, we directly visualize the Dirac mass gap and its disappearance below and above the magnetic order temperature. We further reveal the interplay of Dirac mass gaps and local magnetic defects. We find that, in high defect regions, the Dirac mass gap collapses. Ab initio and coupled Dirac cone model calculations provide insight into the microscopic origin of the correlation between defect density and spatial gap variations. This work provides unambiguous identification of the Dirac mass gap in MnBi2Te4 and, by revealing the microscopic origin of its gap variation, establishes a material design principle for realizing exotic states in intrinsic magnetic topological insulators.
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Topological current divider in a Chern insulator junction. Nat Commun 2022; 13:5967. [PMID: 36216927 PMCID: PMC9550783 DOI: 10.1038/s41467-022-33645-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 09/21/2022] [Indexed: 11/08/2022] Open
Abstract
A Chern insulator is a two-dimensional material that hosts chiral edge states produced by the combination of topology with time reversal symmetry breaking. Such edge states are perfect one-dimensional conductors, which may exist not only on sample edges, but on any boundary between two materials with distinct topological invariants (or Chern numbers). Engineering of such interfaces is highly desirable due to emerging opportunities of using topological edge states for energy-efficient information transmission. Here, we report a chiral edge-current divider based on Chern insulator junctions formed within the layered topological magnet MnBi2Te4. We find that in a device containing a boundary between regions of different thickness, topological domains with different Chern numbers can coexist. At the domain boundary, a Chern insulator junction forms, where we identify a chiral edge mode along the junction interface. We use this to construct topological circuits in which the chiral edge current can be split, rerouted, or switched off by controlling the Chern numbers of the individual domains. Our results demonstrate MnBi2Te4 as an emerging platform for topological circuits design.
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Zhang H, Zhang J, Zhang Y, Yang W, Wang Y, Xu X, Liu F. A generic dual d-band model for interlayer ferromagnetic coupling in a transition-metal doped MnBi 2Te 4 family of materials. NANOSCALE 2022; 14:13689-13695. [PMID: 36093811 DOI: 10.1039/d2nr03283j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Realization of ferromagnetic (FM) interlayer coupling in magnetic topological insulators (TIs) of the MnBi2Te4 family of materials (MBTs) may pave the way for realizing the high-temperature quantum anomalous Hall effect (high-T QAHE). Here we propose a generic dual d-band (DDB) model to elucidate the energy difference (ΔE = EAFM - EFM) between the AFM and FM coupling in transition-metal (TM)-doped MBTs, where the valence of TMs splits into d-t2g and d-eg sub-bands. Remarkably, the DDB shows that ΔE is universally determined by the relative position of the dopant (X) and Mn d-eg/t2g bands, . If ΔEd > 0, then ΔE > 0 and the desired FM coupling is favored. This surprisingly simple rule is confirmed by first-principles calculations of hole-type 3d and 4d TM dopants. Significantly, by applying the DDB model, we predict the high-T QAHE in the V-doped Mn2Bi2Te5, where the Curie temperature is enhanced by doubling of the MnTe layer, while the topological order mitigated by doping can be restored by strain.
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Affiliation(s)
- Huisheng Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Jingjing Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Yaling Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Wenjia Yang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Yingying Wang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Xiaohong Xu
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
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Chen J, Xu W, Tan Z, Pan Z, Zhu P, Liao ZM, Yu D. Superconducting Proximity in Intrinsic Magnetic Topological Insulator MnBi 2Te 4-NbN Hybrid Device Modulated by Coulomb Blockade Effect. NANO LETTERS 2022; 22:6484-6491. [PMID: 35926195 DOI: 10.1021/acs.nanolett.2c00948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The combination of nontrivial topology, magnetism, and superconductivity could offer the potential to realize exotic excitations of quasiparticles. MnBi2Te4, as an intrinsic magnetic topological insulator, may be a good platform to create Majorana fermions if coupled to an s-wave superconductor. Here, we report the transport properties of a MnBi2Te4-NbN hybrid device. This device exhibits clear Coulomb blockade oscillations. We observe a large zero-bias conductance peak that exists over considerable changes in gate voltage, magnetic field, and temperature, which is interpreted as a not fully developed supercurrent. The zero-bias peak shows a nonmonotonic evolution with a magnetic field and an abrupt π phase shift with changing temperature. Zero-energy bound states and a topological phase transition may exist in this hybrid system. Our results provide the first experimental investigation into the properties of the intrinsic magnetic topological insulator/superconductor hybrid structures modulated by the Coulomb blockade effect.
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Affiliation(s)
- Jingjing Chen
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wenzheng Xu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Zhenbing Tan
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Zhencun Pan
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Pengfei Zhu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
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Xu R, Bai Y, Zhou J, Li J, Gu X, Qin N, Yin Z, Du X, Zhang Q, Zhao W, Li Y, Wu Y, Ding C, Wang L, Liang A, Liu Z, Xu Y, Feng X, He K, Chen Y, Yang L. Evolution of the Electronic Structure of Ultrathin MnBi 2Te 4 Films. NANO LETTERS 2022; 22:6320-6327. [PMID: 35894743 DOI: 10.1021/acs.nanolett.2c02034] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ultrathin films of intrinsic magnetic topological insulator MnBi2Te4 exhibit fascinating quantum properties such as the quantum anomalous Hall effect and the axion insulator state. In this work, we systematically investigate the evolution of the electronic structure of MnBi2Te4 thin films. With increasing film thickness, the electronic structure changes from an insulator type with a large energy gap to one with in-gap topological surface states, which is, however, still in drastic contrast to the bulk material. By surface doping of alkali-metal atoms, a Rashba split band gradually emerges and hybridizes with topological surface states, which not only reconciles the puzzling difference between the electronic structures of the bulk and thin-film MnBi2Te4 but also provides an interesting platform to establish Rashba ferromagnet that is attractive for (quantum) anomalous Hall effect. Our results provide important insights into the understanding and engineering of the intriguing quantum properties of MnBi2Te4 thin films.
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Affiliation(s)
- Runzhe Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yunhe Bai
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jingsong Zhou
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jiaheng Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xu Gu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Na Qin
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zhongxu Yin
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xian Du
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qinqin Zhang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Wenxuan Zhao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yidian Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yang Wu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cui Ding
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Lili Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Aiji Liang
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Yong Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xiao Feng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Ke He
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Yulin Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physical Science and Technology, ShanghaiTech University and CAS-Shanghai Science Research Center, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, U.K
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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42
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Li Z, Han Y, Qiao Z. Chern Number Tunable Quantum Anomalous Hall Effect in Monolayer Transitional Metal Oxides via Manipulating Magnetization Orientation. PHYSICAL REVIEW LETTERS 2022; 129:036801. [PMID: 35905371 DOI: 10.1103/physrevlett.129.036801] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/06/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Although much effort has been made to explore quantum anomalous Hall effect (QAHE) in both theory and experiment, the QAHE systems with tunable Chern numbers are yet limited. Here, we theoretically propose that NiAsO_{3} and PdSbO_{3}, monolayer transitional metal oxides, can realize QAHE with tunable Chern numbers via manipulating their magnetization orientations. When the magnetization lies in the x-y plane and all mirror symmetries are broken, the low-Chern-number (i.e., C=±1) phase emerges. When the magnetization exhibits nonzero z-direction component, the system enters the high-Chern-number (i.e., C=±3) phase, even in the presence of canted magnetization. The global band gap can approach the room-temperature energy scale in monolayer PdSbO_{3} (23.4 meV), when the magnetization is aligned to z direction. By using Wannier-based tight-binding model, we establish the phase diagram of magnetization induced topological phase transition. Our work provides a high-temperature QAHE system with tunable Chern number for the practical electronic application.
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Affiliation(s)
- Zeyu Li
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yulei Han
- Department of Physics, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Zhenhua Qiao
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- ICQD, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
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43
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Qian T, Emmanouilidou E, Hu C, Green JC, Mazin II, Ni N. Unconventional Pressure-Driven Metamagnetic Transitions in Topological van der Waals Magnets. NANO LETTERS 2022; 22:5523-5529. [PMID: 35731986 DOI: 10.1021/acs.nanolett.2c01680] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Activating metamagnetic transitions between ordered states in van der Waals magnets and devices bring great opportunities in spintronics. We show that external pressure, which enhances the interlayer hopping without introducing chemical disorders, triggers multiple metamagnetic transitions upon cooling in the topological van der Waals magnets Mn(Bi1-xSbx)4Te7, where the antiferromagnetic interlayer superexchange coupling competes with the ferromagnetic interlayer coupling mediated by the antisite Mn spins. The temperature-pressure phase diagrams reveal that while the ordering temperature from the paramagnetic to ordered states is almost pressure-independent, the metamagnetic transitions show nontrivial pressure and temperature dependence, even re-entrance. For these highly anisotropic magnets, we attribute the former to the ordering temperature being only weakly dependent on the intralayer parameters and the latter to the parametrically different pressure and temperature dependence of the two interlayer couplings. Our independent probing of these disparate magnetic interactions paves an avenue for efficient magnetic manipulations in van der Waals magnets.
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Affiliation(s)
- Tiema Qian
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Eve Emmanouilidou
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Chaowei Hu
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Jazmine C Green
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Igor I Mazin
- Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, United States
- Quantum Science and Engineering Center, George Mason University, Fairfax, Virginia 22030, United States
| | - Ni Ni
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
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Xu HK, Gu M, Fei F, Gu YS, Liu D, Yu QY, Xue SS, Ning XH, Chen B, Xie H, Zhu Z, Guan D, Wang S, Li Y, Liu C, Liu Q, Song F, Zheng H, Jia J. Observation of Magnetism-Induced Topological Edge State in Antiferromagnetic Topological Insulator MnBi 4Te 7. ACS NANO 2022; 16:9810-9818. [PMID: 35695549 DOI: 10.1021/acsnano.2c03622] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Breaking time reversal symmetry in a topological insulator may lead to quantum anomalous Hall effect and axion insulator phase. MnBi4Te7 is a recently discovered antiferromagnetic topological insulator with TN ∼ 12.5 K, which is composed of an alternatively stacked magnetic layer (MnBi2Te4) and nonmagnetic layer (Bi2Te3). By means of scanning tunneling spectroscopy, we clearly observe the electronic state present at a step edge of a magnetic MnBi2Te4 layer but absent at nonmagnetic Bi2Te3 layers at 4.5 K. Furthermore, we find that as the temperature rises above TN the edge state vanishes, while the point defect induced state persists upon an increase in temperature. These results confirm the observation of magnetism-induced edge states. Our analysis based on an axion insulator theory reveals that the nontrivial topological nature of the observed edge state.
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Affiliation(s)
- Hao-Ke Xu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Mingqiang Gu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, Nanjing 210093, China
| | - Yi-Sheng Gu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dang Liu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qiao-Yan Yu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Sha-Sha Xue
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xu-Hui Ning
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, Nanjing 210093, China
| | - Hangkai Xie
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, Nanjing 210093, China
| | - Zhen Zhu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dandan Guan
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shiyong Wang
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yaoyi Li
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Canhua Liu
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qihang Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, Nanjing 210093, China
| | - Hao Zheng
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jinfeng Jia
- School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
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Liang A, Chen C, Zheng H, Xia W, Huang K, Wei L, Yang H, Chen Y, Zhang X, Xu X, Wang M, Guo Y, Yang L, Liu Z, Chen Y. Approaching a Minimal Topological Electronic Structure in Antiferromagnetic Topological Insulator MnBi 2Te 4 via Surface Modification. NANO LETTERS 2022; 22:4307-4314. [PMID: 35604392 DOI: 10.1021/acs.nanolett.1c04930] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The topological electronic structure plays a central role in the nontrivial physical properties in topological quantum materials. A minimal, "hydrogen-atom-like" topological electronic structure is desired for research. In this work, we demonstrate an effort toward the realization of such a system in the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the topological surface state (TSS) via surface modification. Using high resolution laser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES), we found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type surface state (RSS), which could be efficiently removed by the in situ surface potassium (K) dosing. By employing multiple experimental methods to characterize K dosed surface, we attribute such a modification to the electrochemical reactions of K clusters on the surface. Our work not only gives a clear band assignment in MnBi2Te4 but also provides possible new routes in accentuating the topological behavior in the magnetic topological quantum materials.
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Affiliation(s)
- Aiji Liang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Cheng Chen
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, U.K
| | - Huijun Zheng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Kui Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Liyang Wei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Haifeng Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yujie Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xin Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xuguang Xu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Meixiao Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, Shanghai 200031, China
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, U.K
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
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46
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Li G, Wu X, Gao Y, Ma X, Hou F, Cheng H, Huang Q, Wu YC, DeCapua MC, Zhang Y, Lin J, Liu C, Huang L, Zhao Y, Yan J, Huang M. Observation of Ultrastrong Coupling between Substrate and the Magnetic Topological Insulator MnBi 2Te 4. NANO LETTERS 2022; 22:3856-3864. [PMID: 35503660 DOI: 10.1021/acs.nanolett.1c04194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The intrinsic magnetic topological insulator MnBi2Te4 has attracted significant interest recently as a promising platform for exploring exotic quantum phenomena. Here we report that, when atomically thin MnBi2Te4 is deposited on a substrate such as silicon oxide or gold, there is a very strong mechanical coupling between the atomic layer and the supporting substrate. This is manifested as an intense low-frequency breathing Raman mode that is present even for monolayer MnBi2Te4. Interestingly, this coupling turns out to be stronger than the interlayer coupling between the MnBi2Te4 atomic layers. We further found that these low-energy breathing modes are highly sensitive to sample degradation, and they become drastically weaker upon ambient air exposure. This is in contrast to the higher energy optical phonon modes which are much more robust, suggesting that the low-energy Raman modes found here can be an effective indicator of sample quality.
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Affiliation(s)
- Gaomin Li
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Xiaohua Wu
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Yifan Gao
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Xiaoming Ma
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Fuchen Hou
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Hanyan Cheng
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Qiaoling Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Yueh-Chun Wu
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Matthew C DeCapua
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Yujun Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Junhao Lin
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Chang Liu
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Li Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
| | - Yue Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Jun Yan
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Mingyuan Huang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, People's Republic of China
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47
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Rodriguez-Vega M, Lin ZX, Leonardo A, Ernst A, Vergniory MG, Fiete GA. Light-Driven Topological and Magnetic Phase Transitions in Thin Layer Antiferromagnets. J Phys Chem Lett 2022; 13:4152-4158. [PMID: 35507411 PMCID: PMC9109223 DOI: 10.1021/acs.jpclett.2c00070] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 04/19/2022] [Indexed: 05/19/2023]
Abstract
We theoretically study the effect of low-frequency light pulses in resonance with phonons in the topological and magnetically ordered two-septuple layer (2-SL) MnBi2Te4 (MBT) and MnSb2Te4 (MST). These materials share symmetry properties and an antiferromagnetic ground state in pristine form but present different magnetic exchange interactions. In both materials, shear and breathing Raman phonons can be excited via nonlinear interactions with photoexcited infrared phonons using intense laser pulses that can be attained in the current experimental setups. The light-induced transient lattice distortions lead to a change in the sign of the effective interlayer exchange interaction and magnetic order accompanied by a topological band transition. Furthermore, we show that moderate antisite disorder, typically present in MBT and MST samples, can facilitate such an effect. Therefore, our work establishes 2-SL MBT and MST as candidate platforms for achieving non-equilibrium magneto-topological phase transitions.
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Affiliation(s)
- Martin Rodriguez-Vega
- Theoretical
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ze-Xun Lin
- Department
of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
- Department
of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Aritz Leonardo
- Donostia
International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
- EHU
Quantum Center, University of the Basque
Country UPV/EHU, 48940 Leioa, Spain
| | - Arthur Ernst
- Institut
für Theoretische Physik, Johannes
Kepler Universität, A 4040 Linz, Austria
- Max-Planck-Institut
für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - Maia G. Vergniory
- Donostia
International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
- Max
Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
| | - Gregory A. Fiete
- Department
of Physics, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Lujan D, Choe J, Rodriguez-Vega M, Ye Z, Leonardo A, Nunley TN, Chang LJ, Lee SF, Yan J, Fiete GA, He R, Li X. Magnons and magnetic fluctuations in atomically thin MnBi2Te4. Nat Commun 2022; 13:2527. [PMID: 35534477 PMCID: PMC9085848 DOI: 10.1038/s41467-022-29996-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 04/11/2022] [Indexed: 11/24/2022] Open
Abstract
Electron band topology is combined with intrinsic magnetic orders in MnBi2Te4, leading to novel quantum phases. Here we investigate collective spin excitations (i.e. magnons) and spin fluctuations in atomically thin MnBi2Te4 flakes using Raman spectroscopy. In a two-septuple layer with non-trivial topology, magnon characteristics evolve as an external magnetic field tunes the ground state through three ordered phases: antiferromagnet, canted antiferromagnet, and ferromagnet. The Raman selection rules are determined by both the crystal symmetry and magnetic order while the magnon energy is determined by different interaction terms. Using non-interacting spin-wave theory, we extract the spin-wave gap at zero magnetic field, an anisotropy energy, and interlayer exchange in bilayers. We also find magnetic fluctuations increase with reduced thickness, which may contribute to a less robust magnetic order in single layers. MnBi2Te4, referred to as MBT, is a van der Waals material combining topological electron bands with magnetic order. Here, Lujan et al study collective spin excitations in MBT, and show that magnetic fluctuations increase as samples reduce in thickness, implying less robust magnetic order.
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49
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Progress and prospects in magnetic topological materials. Nature 2022; 603:41-51. [PMID: 35236973 DOI: 10.1038/s41586-021-04105-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 10/06/2021] [Indexed: 11/09/2022]
Abstract
Magnetic topological materials represent a class of compounds with properties that are strongly influenced by the topology of their electronic wavefunctions coupled with the magnetic spin configuration. Such materials can support chiral electronic channels of perfect conduction, and can be used for an array of applications, from information storage and control to dissipationless spin and charge transport. Here we review the theoretical and experimental progress achieved in the field of magnetic topological materials, beginning with the theoretical prediction of the quantum anomalous Hall effect without Landau levels, and leading to the recent discoveries of magnetic Weyl semimetals and antiferromagnetic topological insulators. We outline recent theoretical progress that has resulted in the tabulation of, for the first time, all magnetic symmetry group representations and topology. We describe several experiments realizing Chern insulators, Weyl and Dirac magnetic semimetals, and an array of axionic and higher-order topological phases of matter, and we survey future perspectives.
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50
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Wang C, Xiao RC, Liu H, Zhang Z, Lai S, Zhu C, Cai H, Wang N, Chen S, Deng Y, Liu Z, Yang SA, Gao WB. Room-temperature third-order nonlinear Hall effect in Weyl semimetal TaIrTe 4. Natl Sci Rev 2022; 9:nwac020. [PMID: 36694799 PMCID: PMC9869080 DOI: 10.1093/nsr/nwac020] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 01/27/2023] Open
Abstract
The second-order nonlinear Hall effect observed in the time-reversal symmetric system has not only shown abundant physical content, but also exhibited potential application prospects. Recently, a third-order nonlinear Hall effect has been observed in MoTe2 and WTe2. However, few-layer MoTe2 and WTe2 are usually unstable in air and the observed third-order nonlinear Hall effect can be measured only at low temperature, which hinders further investigation as well as potential application. Thus, exploring new air-stable material systems with a sizable third-order nonlinear Hall effect at room temperature is an urgent task. Here, in type-II Weyl semimetal TaIrTe4, we observed a pronounced third-order nonlinear Hall effect, which can exist at room temperature and remain stable for months. The third-order nonlinear Hall effect is connected to the Berry-connection polarizability tensor instead of the Berry curvature. The possible mechanism of the observation of the third-order nonlinear Hall effect in TaIrTe4 at room temperature has been discussed. Our findings will open an avenue towards exploring room-temperature nonlinear devices in new quantum materials.
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Affiliation(s)
| | | | - Huiying Liu
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore487372, Singapore
| | - Zhaowei Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Shen Lai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
| | - Hongbing Cai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Naizhou Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore637371, Singapore
| | - Shengyao Chen
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing100190, China
| | - Ya Deng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore639798, Singapore
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