1
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Nguyen KD, Lee W, Dang J, Wu T, Berruto G, Yan C, Ip CIJ, Lin H, Gao Q, Lee SH, Yan B, Liu C, Mao Z, Zhang XX, Yang S. Distinguishing surface and bulk electromagnetism via their dynamics in an intrinsic magnetic topological insulator. SCIENCE ADVANCES 2024; 10:eadn5696. [PMID: 39121229 PMCID: PMC11313949 DOI: 10.1126/sciadv.adn5696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 07/02/2024] [Indexed: 08/11/2024]
Abstract
The indirect exchange interaction between local magnetic moments via surface electrons has been long predicted to bolster the surface ferromagnetism in magnetic topological insulators (MTIs), which facilitates the quantum anomalous Hall effect. This unconventional effect is critical to determining the operating temperatures of future topotronic devices. However, the experimental confirmation of this mechanism remains elusive, especially in intrinsic MTIs. Here, we combine time-resolved photoemission spectroscopy with time-resolved magneto-optical Kerr effect measurements to elucidate the unique electromagnetism at the surface of an intrinsic MTI MnBi2Te4. Theoretical modeling based on 2D Ruderman-Kittel-Kasuya-Yosida interactions captures the initial quenching of a surface-rooted exchange gap within a factor of two but overestimates the bulk demagnetization by one order of magnitude. This mechanism directly explains the sizable gap in the quasi-2D electronic state and the nonzero residual magnetization in even-layer MnBi2Te4. Furthermore, it leads to efficient light-induced demagnetization comparable to state-of-the-art magnetophotonic crystals, promising an effective manipulation of magnetism and topological orders for future topotronics.
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Affiliation(s)
- Khanh Duy Nguyen
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Woojoo Lee
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Jianchen Dang
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
| | - Tongyao Wu
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
| | - Gabriele Berruto
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Chenhui Yan
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Chi Ian Jess Ip
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Haoran Lin
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Qiang Gao
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Seng Huat Lee
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Chaoxing Liu
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Zhiqiang Mao
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Xiao-Xiao Zhang
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
| | - Shuolong Yang
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
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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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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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5
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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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6
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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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7
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Kaplan D, Holder T, Yan B. Unification of Nonlinear Anomalous Hall Effect and Nonreciprocal Magnetoresistance in Metals by the Quantum Geometry. PHYSICAL REVIEW LETTERS 2024; 132:026301. [PMID: 38277599 DOI: 10.1103/physrevlett.132.026301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 07/09/2023] [Accepted: 11/16/2023] [Indexed: 01/28/2024]
Abstract
The quantum geometry has significant consequences in determining transport and optical properties in quantum materials. Here, we use a semiclassical formalism coupled with perturbative corrections unifying the nonlinear anomalous Hall effect and nonreciprocal magnetoresistance (longitudinal resistance) from the quantum geometry. In the dc limit, both transverse and longitudinal nonlinear conductivities include a term due to the normalized quantum metric dipole. The quantum metric contribution is intrinsic and does not scale with the quasiparticle lifetime. We demonstrate the coexistence of a nonlinear anomalous Hall effect and nonreciprocal magnetoresistance in films of the doped antiferromagnetic topological insulator MnBi_{2}Te_{4}. Our work indicates that both longitudinal and transverse nonlinear transport provide a sensitive probe of the quantum geometry in solids.
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Affiliation(s)
- Daniel Kaplan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tobias Holder
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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8
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Hu X, He X, Guo Z, Kamiya T, Wu J. Antisite-Defects Control of Magnetic Properties in MnSb 2Te 4. ACS NANO 2024; 18:738-749. [PMID: 38127649 DOI: 10.1021/acsnano.3c09064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The intrinsic magnetic topological materials Mn(Sb/Bi)2n+2Te3n+4 have attracted extensive attention due to their topological quantum properties. Although, the Mn-Sb/Bi antisite defects have been frequently reported to exert significant influences on both magnetism and band topology, their formation mechanism and the methods to manipulate their distribution and concentration remain elusive. Here, we present MnSb2Te4 as a typical example and demonstrate that Mn-Sb antisite defects and magnetism can be tuned by controlling the crystal growth conditions. The cooling rate is identified as the primary key parameter. Magnetization and chemical analysis demonstrate that a slower cooling rate would lead to a higher Mn concentration, a higher magnetic transition temperature, and a higher saturation moment. Further analysis indicates that the Mn content at the original Mn site (MnMn, 3a site) varies more significantly with the cooling rate than the Mn content at the Sb site (MnSb, 6c site). Based on experimental observations, magnetic phase diagrams regarding MnMn and MnSb concentrations are constructed. With the assistance of first-principles calculations, it is demonstrated that the Mn-Sb mixing states primarily result from the mixing entropy and the growth kinetics. The present findings offer valuable insights into defects engineering for preparation of two-dimensional quantum materials.
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Affiliation(s)
- Xinmeng Hu
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xinyi He
- MDX Research Center for Element Strategy, International Research Frontiers Initiative, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Zhilin Guo
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Toshio Kamiya
- MDX Research Center for Element Strategy, International Research Frontiers Initiative, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Jiazhen Wu
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Micro/Nano-Porous Functional Materials, Southern University of Science and Technology, Shenzhen 518055, China
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9
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Ahn J, Kang SH, Yoon M, Ganesh P, Krogel JT. Stacking Faults and Topological Properties in MnBi 2Te 4: Reconciling Gapped and Gapless States. J Phys Chem Lett 2023; 14:9052-9059. [PMID: 37782759 DOI: 10.1021/acs.jpclett.3c01939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Despite theoretical predictions of a gapped surface state for the magnetic topological insulator MnBi2Te4 (MBT), there has been a series of experimental evidence pointing toward gapless states. Here, we theoretically explore how stacking faults could influence the topological characteristics of MBT. We envisage a scenario that a stacking fault exists at the surface of MBT, causing the uppermost layer to deviate from the ground state and its interlayer separation to be expanded. This stacking fault with modulated interlayer couplings hosts a nearly gapless state within the topmost layer due to charge redistribution as the outermost layer recedes. Furthermore, we find evidence of spin-momentum locking and preservation of weak band inversion in the gapless surface state, suggesting the nontrivial topological surface states in the presence of the stacking fault. Our findings provide a plausible elucidation to the long-standing conundrum of reconciling the observation of gapped and gapless states on MBT surfaces.
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Affiliation(s)
- Jeonghwan Ahn
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Seoung-Hun Kang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Mina Yoon
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jaron T Krogel
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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10
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Shikin AM, Estyunina TP, Eryzhenkov AV, Zaitsev NL, Tarasov AV. Topological phase transition in the antiferromagnetic topological insulator MnBi[Formula: see text]Te[Formula: see text] from the point of view of axion-like state realization. Sci Rep 2023; 13:16343. [PMID: 37770454 PMCID: PMC10539541 DOI: 10.1038/s41598-023-42466-7] [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: 07/07/2023] [Accepted: 09/11/2023] [Indexed: 09/30/2023] Open
Abstract
This work aims to study the conditions of topological phase transition (TPT) between the topological and trivial states in the antiferromagnetic topological insulator (AFM TI) MnBi[Formula: see text]Te[Formula: see text] and propose some theory about the relationship of this TPT with the possibility of axion-like state realization in this material. Using the density functional approach we have analyzed the changes in the electronic and spin structure of topological surface states (TSSs) and the nearest conduction and valence bands (CB and VB) including the changes in the bulk band gap as well as the Dirac point (DP) gap in TSSs under variation of the spin-orbit coupling strength in the region of the TPT for infinite crystal and slab with a surface both. We have shown that in both cases the TPT occurs with inversion of the contributions of the Bi-[Formula: see text] and Te-[Formula: see text] states of different parity at the gap edges related to change in the gap sign. In the case of surface calculations, the Bi-[Formula: see text] and Te-[Formula: see text] states at the edges of the bulk band gap and their inversion at the TPT point are transformed into the TSSs with an energy gap at the DP. In this case the TPT takes place without closing the band gap, i.e. with a "jump" through zero and the formation of the nonzero gap during such a transition. Our calculations show that the TPT point is also characterized by an inversion of the out-of-plane spin polarization [Formula: see text] at the [Formula: see text] point for lower and upper parts of the Dirac cone and a significant spatial redistribution of the TSSs between the surface and the bulk. We suppose that the nonzero Dirac gap can have some relationship with the formation of the axion-like state, which presumably couples nonmagnetic spin-orbit and magnetic contributions at the boundary between the topological and trivial phases for a system with parameters close to the TPT conditions. A practically realized system is proposed - the AFM TI with a stoichiometry close to that of MnBi[Formula: see text]Te[Formula: see text]Se[Formula: see text] with partial (about 50%) substitution of Te atoms for Se atoms in MnBi[Formula: see text]Te[Formula: see text] which can be an experimental platform for the implementation and experimental analysis of the TPT and the corresponding possibility of the axion-like state realization in Condensed Matter. Besides, such system could serve as a good platform for studying the dynamic axion effect, where the axion field fluctuations are maximised when a small external field is applied to the system which state is close to the TPT.
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Affiliation(s)
- A. M. Shikin
- St. Petersburg State University, St. Petersburg, Russia 198504
| | - T. P. Estyunina
- St. Petersburg State University, St. Petersburg, Russia 198504
| | | | - N. L. Zaitsev
- St. Petersburg State University, St. Petersburg, Russia 198504
- Institute of Molecule and Crystal Physics, Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Ufa, Russia 450075
| | - A. V. Tarasov
- St. Petersburg State University, St. Petersburg, Russia 198504
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11
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Abstract
MnBi2Te4, an antiferromagnetic topological insulator, was theoretically predicted to have a gapped surface state on its (111) surface. However, a much smaller gapped or even gapless surface state has been observed experimentally, which is thought to be caused by the defects in MnBi2Te4. Here, we have theoretically identified the antisite MnBi and BiMn as dominant defects and revealed their evolution during the phase transition from MnTe/Bi2Te3 to MnBi2Te4. We found that the complete elimination of MnBi and BiMn defects in MnBi2Te4 by simple annealing is almost impossible due to the high migration barrier in kinetics. Moreover, the gap of the Dirac point-related bands in a MnBi2Te4 monolayer would be eliminated with an increasing concentration of MnBi and BiMn defects, which could explain the experimentally unobserved large-gap surface state in MnBi2Te4. Our results provide an insight into the theoretical understanding of the quality and the experimentally measured topological properties of the synthesized MnBi2Te4.
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Affiliation(s)
- Xi Wu
- Shenzhen Geim Graphene Center and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Chao Ruan
- Shenzhen Geim Graphene Center and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Peizhe Tang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - Feiyu Kang
- Shenzhen Geim Graphene Center and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Wenhui Duan
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Jia Li
- Shenzhen Geim Graphene Center and Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
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