1
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Yao X, Cui Q, Huang Z, Yuan X, Yi HT, Jain D, Kisslinger K, Han MG, Wu W, Yang H, Oh S. Atomic-Layer-Controlled Magnetic Orders in MnBi 2Te 4-Bi 2Te 3 Topological Heterostructures. NANO LETTERS 2024; 24:9923-9930. [PMID: 39078726 DOI: 10.1021/acs.nanolett.4c02320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
The natural van der Waals superlattice MnBi2Te4-(Bi2Te3)m provides an optimal platform to combine topology and magnetism in one system with minimal structural disorder. Here, we show that this system can harbor both ferromagnetic (FM) and antiferromagnetic (AFM) orders and that these magnetic orders can be controlled in two different ways by either varying the Mn-Mn distance while keeping the Bi2Te3/MnBi2Te4 ratio constant or vice versa. We achieve this by creating atomically engineered sandwich structures composed of Bi2Te3 and MnBi2Te4 layers. We show that the AFM order is exclusively determined by the Mn-Mn distance, whereas the FM order depends only on the overall Bi2Te3/MnBi2Te4 ratio regardless of the distance between the MnBi2Te4 layers. Our results shed light on the origins of the AFM and FM orders and provide insights into how to manipulate magnetic orders not only for the MnBi2Te4-Bi2Te3 system but also for other magneto-topological materials.
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Affiliation(s)
- Xiong Yao
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Center for Quantum Materials Synthesis and Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Qirui Cui
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Center for Quantum Matter, School of Physics, Zhejiang University, Hangzhou 310058, China
| | - Zengle Huang
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Xiaoyu Yuan
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Hee Taek Yi
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Deepti Jain
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Kim Kisslinger
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Myung-Geun Han
- Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Weida Wu
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Hongxin Yang
- Center for Quantum Matter, School of Physics, Zhejiang University, Hangzhou 310058, China
| | - Seongshik Oh
- Center for Quantum Materials Synthesis and Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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2
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Hu J, Han Y, Chi X, Omar GJ, Al Ezzi MME, Gou J, Yu X, Andrivo R, Watanabe K, Taniguchi T, Wee ATS, Qiao Z, Ariando A. Tunable Spin-Polarized States in Graphene on a Ferrimagnetic Oxide Insulator. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305763. [PMID: 37811809 DOI: 10.1002/adma.202305763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 10/01/2023] [Indexed: 10/10/2023]
Abstract
Spin-polarized two-dimensional (2D) materials with large and tunable spin-splitting energy promise the field of 2D spintronics. While graphene has been a canonical 2D material, its spin properties and tunability are limited. Here, this work demonstrates the emergence of robust spin-polarization in graphene with large and tunable spin-splitting energy of up to 132 meV at zero applied magnetic fields. The spin polarization is induced through a magnetic exchange interaction between graphene and the underlying ferrimagnetic oxide insulating layer, Tm3 Fe5 O12 , as confirmed by its X-ray magnetic circular dichroism (XMCD). The spin-splitting energies are directly measured and visualized by the shift in their Landau-fan diagram mapped by analyzing the measured Shubnikov-de-Haas (SdH) oscillations as a function of applied electric fields, showing consistent fit with the first-principles and machine learning calculations. Further, the observed spin-splitting energies can be tuned over a broad range between 98 and 166 meV by field cooling. The methods and results are applicable to other 2D (magnetic) materials and heterostructures, and offer great potential for developing next-generation spin logic and memory devices.
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Affiliation(s)
- Junxiong Hu
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Yulei Han
- International Center for Quantum Design of Functional Materials, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Department of Physics, Fuzhou University, Fuzhou, Fujian, 350108, China
| | - Xiao Chi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ganesh Ji Omar
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Mohammed Mohammed Esmail Al Ezzi
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117551, Singapore
| | - Jian Gou
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Rusydi Andrivo
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhenhua Qiao
- International Center for Quantum Design of Functional Materials, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, China
| | - A Ariando
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
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3
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Altena M, Jansen T, Tsvetanova M, Brinkman A. Phase Separation Prevents the Synthesis of VBi 2Te 4 by Molecular Beam Epitaxy. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:87. [PMID: 38202542 PMCID: PMC10780430 DOI: 10.3390/nano14010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/17/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024]
Abstract
Intrinsic magnetic topological insulators (IMTIs) have a non-trivial band topology in combination with magnetic order. This potentially leads to fascinating states of matter, such as quantum anomalous Hall (QAH) insulators and axion insulators. One of the theoretically predicted IMTIs is VBi2Te4, but experimental evidence of this material is lacking so far. Here, we report on our attempts to synthesise VBi2Te4 by molecular beam epitaxy (MBE). X-ray diffraction reveals that in the thermodynamic phase space reachable by MBE, there is no region where VBi2Te4 is stably synthesised. Moreover, scanning transmission electron microscopy shows a clear phase separation to Bi2Te3 and VTe2 instead of the formation of VBi2Te4. We suggest the phase instability to be due to either the large lattice mismatch between VTe2 and Bi2Te3 or the unfavourable valence state of vanadium.
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Affiliation(s)
- Marieke Altena
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - Thies Jansen
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
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4
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Vakili H, Ganguly S, de Coster GJ, Neupane MR, Ghosh AW. Low Power In-Memory Computation with Reciprocal Ferromagnet/Topological Insulator Heterostructures. ACS NANO 2022; 16:20222-20228. [PMID: 36459145 PMCID: PMC9798907 DOI: 10.1021/acsnano.2c05645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
The surface state of a 3D topological insulator (3DTI) is a spin-momentum locked conductive state, whose large spin hall angle can be used for the energy-efficient spin-orbit torque based switching of an overlying ferromagnet (FM). Conversely, the gated switching of the magnetization of a separate FM in or out of the TI surface plane can turn on and off the TI surface current. By exploiting this reciprocal behavior, we can use two FM/3DTI heterostructures to design an integrated 1-transistor 1-magnetic tunnel junction random access memory unit (1T1MTJ RAM) for an ultra low power Processing-in-Memory (PiM) architecture. Our calculation involves combining the Fokker-Planck equation with the Nonequilibrium Green Function (NEGF) based flow of conduction electrons and Landau-Lifshitz-Gilbert (LLG) based dynamics of magnetization. Our combined approach allows us to connect device performance metrics with underlying material parameters, which can guide proposed experimental and fabrication efforts.
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Affiliation(s)
- Hamed Vakili
- Department
of Physics, University of Virginia, Charlottesville, Virginia22904, United States
| | - Samiran Ganguly
- Department
of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia22904, United States
- Department
of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia23284, United States
| | - George J. de Coster
- DEVCOM
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland20783, United
States
| | - Mahesh R. Neupane
- DEVCOM
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland20783, United
States
- Materials
Science and Engineering Program, University
of California, Riverside, California92521, United States
| | - Avik W. Ghosh
- Department
of Physics, University of Virginia, Charlottesville, Virginia22904, United States
- Department
of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia22904, United States
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5
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Zhang G, Wu H, Zhang L, Yang L, Xie Y, Guo F, Li H, Tao B, Wang G, Zhang W, Chang H. Two-Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204380. [PMID: 36135779 DOI: 10.1002/smll.202204380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Over the past decade, 2D van der Waals (vdW) topological materials (TMs), including topological insulators and topological semimetals, which combine atomically flat 2D layers and topologically nontrivial band structures, have attracted increasing attention in condensed-matter physics and materials science. These easily cleavable and integrated TMs provide the ideal platform for exploring topological physics in the 2D limit, where new physical phenomena may emerge, and represent a potential to control and investigate exotic properties and device applications in nanoscale topological phases. However, multifaced efforts are still necessary, which is the prerequisite for the practical application of 2D vdW TMs. Herein, this review focuses on the preparation, properties, and device applications of 2D vdW TMs. First, three common preparation strategies for 2D vdW TMs are summarized, including single crystal exfoliation, chemical vapor deposition, and molecular beam epitaxy. Second, the origin and regulation of various properties of 2D vdW TMs are introduced, involving electronic properties, transport properties, optoelectronic properties, thermoelectricity, ferroelectricity, and magnetism. Third, some device applications of 2D vdW TMs are presented, including field-effect transistors, memories, spintronic devices, and photodetectors. Finally, some significant challenges and opportunities for the practical application of 2D vdW TMs in 2D topological electronics are briefly addressed.
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Affiliation(s)
- Gaojie Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Wu
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Liang Zhang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Li Yang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuanmiao Xie
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Fei Guo
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Hongda Li
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Boran Tao
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Guofu Wang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Wenfeng Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
| | - Haixin Chang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
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6
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Llacsahuanga Allcca AE, Pan XC, Miotkowski I, Tanigaki K, Chen YP. Gate-Tunable Anomalous Hall Effect in Stacked van der Waals Ferromagnetic Insulator-Topological Insulator Heterostructures. NANO LETTERS 2022; 22:8130-8136. [PMID: 36215229 DOI: 10.1021/acs.nanolett.2c02571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The search of novel topological states, such as the quantum anomalous Hall insulator and chiral Majorana fermions, has motivated different schemes to introduce magnetism into topological insulators. A promising scheme is using the magnetic proximity effect (MPE), where a ferromagnetic insulator magnetizes the topological insulator. Most of these heterostructures are synthesized by growth techniques which prevent mixing many of the available ferromagnetic and topological insulators due to difference in growth conditions. Here, we demonstrate that MPE can be obtained in heterostructures stacked via the dry transfer of flakes of van der Waals ferromagnetic and topological insulators (Cr2Ge2Te6/BiSbTeSe2), as evidenced in the observation of an anomalous Hall effect (AHE). Furthermore, devices made from these heterostructures allow modulation of the AHE when controlling the carrier density via electrostatic gating. These results show that simple mechanical transfer of magnetic van der Waals materials provides another possible avenue to magnetize topological insulators by MPE.
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Affiliation(s)
- Andres E Llacsahuanga Allcca
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Quantum Science and Engineering Institute and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Xing-Chen Pan
- WPI Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Ireneusz Miotkowski
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Katsumi Tanigaki
- WPI Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Yong P Chen
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Quantum Science and Engineering Institute and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
- WPI Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Institute of Physics and Astronomy and Villum Center for Hybrid Quantum Materials and Devices, Aarhus University, 8000 Aarhus-C, Denmark
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai 980-8577, Japan
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7
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Gupta V, Jain R, Ren Y, Zhang XS, Alnaser HF, Vashist A, Deshpande VV, Muller DA, Xiao D, Sparks TD, Ralph DC. Gate-Tunable Anomalous Hall Effect in a 3D Topological Insulator/2D Magnet van der Waals Heterostructure. NANO LETTERS 2022; 22:7166-7172. [PMID: 35994426 DOI: 10.1021/acs.nanolett.2c02440] [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
We demonstrate advantages of samples made by mechanical stacking of exfoliated van der Waals materials for controlling the topological surface state of a three-dimensional topological insulator (TI) via interaction with an adjacent magnet layer. We assemble bilayers with pristine interfaces using exfoliated flakes of the TI BiSbTeSe2 and the magnet Cr2Ge2Te6, thereby avoiding problems caused by interdiffusion that can affect interfaces made by top-down deposition methods. The samples exhibit an anomalous Hall effect (AHE) with abrupt hysteretic switching. For the first time in samples composed of a TI and a separate ferromagnetic layer, we demonstrate that the amplitude of the AHE can be tuned via gate voltage with a strong peak near the Dirac point. This is the signature expected for the AHE due to Berry curvature associated with an exchange gap induced by interaction between the topological surface state and an out-of-plane-oriented magnet.
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Affiliation(s)
- Vishakha Gupta
- Cornell University, Ithaca, New York 14850, United States
| | - Rakshit Jain
- Cornell University, Ithaca, New York 14850, United States
| | - Yafei Ren
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Xiyue S Zhang
- Cornell University, Ithaca, New York 14850, United States
| | - Husain F Alnaser
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Amit Vashist
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Vikram V Deshpande
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - David A Muller
- Cornell University, Ithaca, New York 14850, United States
- Kavli Institute at Cornell, Ithaca, New York 14853, United States
| | - Di Xiao
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Taylor D Sparks
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Daniel C Ralph
- Cornell University, Ithaca, New York 14850, United States
- Kavli Institute at Cornell, Ithaca, New York 14853, United States
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8
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Li J, Rashetnia M, Lohmann M, Koo J, Xu Y, Zhang X, Watanabe K, Taniguchi T, Jia S, Chen X, Yan B, Cui YT, Shi J. Proximity-magnetized quantum spin Hall insulator: monolayer 1 T' WTe 2/Cr 2Ge 2Te 6. Nat Commun 2022; 13:5134. [PMID: 36050322 PMCID: PMC9436961 DOI: 10.1038/s41467-022-32808-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 08/18/2022] [Indexed: 11/20/2022] Open
Abstract
Van der Waals heterostructures offer great versatility to tailor unique interactions at the atomically flat interfaces between dissimilar layered materials and induce novel physical phenomena. By bringing monolayer 1 T’ WTe2, a two-dimensional quantum spin Hall insulator, and few-layer Cr2Ge2Te6, an insulating ferromagnet, into close proximity in an heterostructure, we introduce a ferromagnetic order in the former via the interfacial exchange interaction. The ferromagnetism in WTe2 manifests in the anomalous Nernst effect, anomalous Hall effect as well as anisotropic magnetoresistance effect. Using local electrodes, we identify separate transport contributions from the metallic edge and insulating bulk. When driven by an AC current, the second harmonic voltage responses closely resemble the anomalous Nernst responses to AC temperature gradient generated by nonlocal heater, which appear as nonreciprocal signals with respect to the induced magnetization orientation. Our results from different electrodes reveal spin-polarized edge states in the magnetized quantum spin Hall insulator. Van der Waals heterostructures allow for the integration of several materials with different properties in the one heterostructure. Here, Li et al combine a quantum spin hall insulator, WTe2, with an insulating ferromagnet, Cr2Ge2Te6, in a van der Waals heterostructure, with resulting proximity-induced magnetism in the WTe2 layer leading to an anomalous Hall and Nernst effect.
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Affiliation(s)
- Junxue Li
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.,Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Mina Rashetnia
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Mark Lohmann
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Jahyun Koo
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Youming Xu
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521, USA
| | - Xiao Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Xi Chen
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521, USA
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Yong-Tao Cui
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
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9
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Deng P, Grutter A, Han Y, Holtz ME, Zhang P, Quarterman P, Pan S, Qi S, Qiao Z, Wang KL. Topological Surface State Annihilation and Creation in SnTe/Cr x(BiSb) 2-xTe 3 Heterostructures. NANO LETTERS 2022; 22:5735-5741. [PMID: 35850534 DOI: 10.1021/acs.nanolett.2c00774] [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
Topological surface states are a new class of electronic states with novel properties, including the potential for annihilation between surface states from two topological insulators at a common interface. Here, we report the annihilation and creation of topological surface states in the SnTe/Crx(BiSb)2-xTe3 (CBST) heterostructures as evidenced by magneto-transport, polarized neutron reflectometry, and first-principles calculations. Our results show that topological surface states are induced in the otherwise topologically trivial two-quintuple-layers thick CBST when interfaced with SnTe, as a result of the surface state annihilation at the SnTe/CBST interface. Moreover, we unveiled systematic changes in the transport behaviors of the heterostructures with respect to changing Fermi level and thickness. Our observation of surface state creation and annihilation demonstrates a promising way of designing and engineering topological surface states for dissipationless electronics.
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Affiliation(s)
- Peng Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
- Beijing Academy of Quantum Information Science, Beijing 100193, China
| | - Alexander Grutter
- NIST Center for Neutron Research, National Institute of Standards and Technology, Maryland 20899-6102, United States
| | - Yulei Han
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Anhui 230026, China
| | - Megan E Holtz
- Materials Measurement Laboratory, National Institute of Standards and Technology, Maryland 20899-6102, United States
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
| | - Patrick Quarterman
- NIST Center for Neutron Research, National Institute of Standards and Technology, Maryland 20899-6102, United States
| | - Shuaihang Pan
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095, United States
| | - Shifei Qi
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Anhui 230026, China
- College of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Hebei 050024, China
| | - Zhenhua Qiao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Maryland 20899-6102, United States
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, United States
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States
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10
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Choi E, Sim KI, Burch KS, Lee YH. Emergent Multifunctional Magnetic Proximity in van der Waals Layered Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200186. [PMID: 35596612 PMCID: PMC9313546 DOI: 10.1002/advs.202200186] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/01/2022] [Indexed: 05/10/2023]
Abstract
Proximity effect, which is the coupling between distinct order parameters across interfaces of heterostructures, has attracted immense interest owing to the customizable multifunctionalities of diverse 3D materials. This facilitates various physical phenomena, such as spin order, charge transfer, spin torque, spin density wave, spin current, skyrmions, and Majorana fermions. These exotic physics play important roles for future spintronic applications. Nevertheless, several fundamental challenges remain for effective applications: unavoidable disorder and lattice mismatch limits in the growth process, short characteristic length of proximity, magnetic fluctuation in ultrathin films, and relatively weak spin-orbit coupling (SOC). Meanwhile, the extensive library of atomically thin, 2D van der Waals (vdW) layered materials, with unique characteristics such as strong SOC, magnetic anisotropy, and ultraclean surfaces, offers many opportunities to tailor versatile and more effective functionalities through proximity effects. Here, this paper focuses on magnetic proximity, i.e., proximitized magnetism and reviews the engineering of magnetism-related functionalities in 2D vdW layered heterostructures for next-generation electronic and spintronic devices. The essential factors of magnetism and interfacial engineering induced by magnetic layers are studied. The current limitations and future challenges associated with magnetic proximity-related physics phenomena in 2D heterostructures are further discussed.
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Affiliation(s)
- Eun‐Mi Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kyung Ik Sim
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
| | - Kenneth S. Burch
- Department of PhysicsBoston College140 Commonwealth AveChestnut HillMA02467‐3804USA
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS)Sungkyunkwan University (SKKU)Suwon16419Republic of Korea
- Department of Energy ScienceSungkyunkwan UniversitySuwon16419Republic of Korea
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11
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Riddiford LJ, Grutter AJ, Pillsbury T, Stanley M, Reifsnyder Hickey D, Li P, Alem N, Samarth N, Suzuki Y. Understanding Signatures of Emergent Magnetism in Topological Insulator/Ferrite Bilayers. PHYSICAL REVIEW LETTERS 2022; 128:126802. [PMID: 35394317 DOI: 10.1103/physrevlett.128.126802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/21/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Magnetic insulator-topological insulator heterostructures have been studied in search of chiral edge states via proximity induced magnetism in the topological insulator, but these states have been elusive. We identified MgAl_{0.5}Fe_{1.5}O_{4}/Bi_{2}Se_{3} bilayers for a possible magnetic proximity effect. Electrical transport and polarized neutron reflectometry suggest a proximity effect, but structural data indicate a disordered interface as the origin of the magnetic response. Our results provide a strategy via correlation of microstructure with magnetic data to confirm a magnetic proximity effect.
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Affiliation(s)
- Lauren J Riddiford
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Alexander J Grutter
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Timothy Pillsbury
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Max Stanley
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Danielle Reifsnyder Hickey
- Department of Materials Science, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Peng Li
- Department of Electrical Engineering and Computer Science, Auburn University, Auburn University, Auburn, Alabama 36849, USA
| | - Nasim Alem
- Department of Materials Science, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yuri Suzuki
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
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12
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Ultrafast photothermoelectric effect in Dirac semimetallic Cd 3As 2 revealed by terahertz emission. Nat Commun 2022; 13:1623. [PMID: 35338125 PMCID: PMC8956572 DOI: 10.1038/s41467-022-29168-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz) emission from the transient photocurrent induced by these effects. Our excitation polarization and power dependence confirm that the observed THz emission is due to photothermoelectric effect instead of other nonlinear optical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied, the response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation compared to the photo-Seebeck effect. Such enhancement supports an ambipolar transport nature of the photo-Nernst current generation in Cd3As2. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect, and our transient studies pave the way for thermoelectric devices applicable for high field circumstance when nonequilibrium state matters. The large THz emission due to highly efficient photothermoelectric conversion is comparable to conventional semiconductors through optical rectification and photo-Dember effect. Many topological semimetals are excellent thermoelectric materials, but previous studies were limited to steady-state properties. Here, the authors observe a transient thermoelectric response in Cd3As2 by detecting the resulting THz emission, with an enhanced response when a small magnetic field is applied.
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13
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Zou WJ, Guo MX, Wong JF, Huang ZP, Chia JM, Chen WN, Wang SX, Lin KY, Young LB, Lin YHG, Yahyavi M, Wu CT, Jeng HT, Lee SF, Chang TR, Hong M, Kwo J. Enormous Berry-Curvature-Based Anomalous Hall Effect in Topological Insulator (Bi,Sb) 2Te 3 on Ferrimagnetic Europium Iron Garnet beyond 400 K. ACS NANO 2022; 16:2369-2380. [PMID: 35099945 DOI: 10.1021/acsnano.1c08663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To realize the quantum anomalous Hall effect (QAHE) at elevated temperatures, the approach of magnetic proximity effect (MPE) was adopted to break the time-reversal symmetry in the topological insulator (Bi0.3Sb0.7)2Te3 (BST) based heterostructures with a ferrimagnetic insulator europium iron garnet (EuIG) of perpendicular magnetic anisotropy. Here we demonstrate large anomalous Hall resistance (RAHE) exceeding 8 Ω (ρAHE of 3.2 μΩ·cm) at 300 K and sustaining to 400 K in 35 BST/EuIG samples, surpassing the past record of 0.28 Ω (ρAHE of 0.14 μΩ·cm) at 300 K. The large RAHE is attributed to an atomically abrupt, Fe-rich interface between BST and EuIG. Importantly, the gate dependence of the AHE loops shows no sign change with varying chemical potential. This observation is supported by our first-principles calculations via applying a gradient Zeeman field plus a contact potential on BST. Our calculations further demonstrate that the AHE in this heterostructure is attributed to the intrinsic Berry curvature. Furthermore, for gate-biased 4 nm BST on EuIG, a pronounced topological Hall effect-like (THE-like) feature coexisting with AHE is observed at the negative top-gate voltage up to 15 K. Interface tuning with theoretical calculations has realized topologically distinct phenomena in tailored magnetic TI-based heterostructures.
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Affiliation(s)
- Wei-Jhih Zou
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Meng-Xin Guo
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Jyun-Fong Wong
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Zih-Ping Huang
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jui-Min Chia
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Wei-Nien Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sheng-Xin Wang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Keng-Yung Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Lawrence Boyu Young
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Yen-Hsun Glen Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Mohammad Yahyavi
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Chien-Ting Wu
- Materials Analysis Division, Taiwan Semiconductor Research Institute, National Applied Research Laboratories, Hsinchu 300091, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
- Physics Division, National Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Shang-Fan Lee
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Physics Division, National Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan
- Center for Quantum Frontiers of Research and Technology (QFort), Tainan 701, Taiwan
| | - Minghwei Hong
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jueinai Kwo
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
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14
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Liu J, Hesjedal T. Magnetic Topological Insulator Heterostructures: A Review. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021:e2102427. [PMID: 34665482 DOI: 10.1002/adma.202102427] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/05/2021] [Indexed: 06/13/2023]
Abstract
Topological insulators (TIs) provide intriguing prospects for the future of spintronics due to their large spin-orbit coupling and dissipationless, counter-propagating conduction channels in the surface state. The combination of topological properties and magnetic order can lead to new quantum states including the quantum anomalous Hall effect that was first experimentally realized in Cr-doped (Bi,Sb)2 Te3 films. Since magnetic doping can introduce detrimental effects, requiring very low operational temperatures, alternative approaches are explored. Proximity coupling to magnetically ordered systems is an obvious option, with the prospect to raise the temperature for observing the various quantum effects. Here, an overview of proximity coupling and interfacial effects in TI heterostructures is presented, which provides a versatile materials platform for tuning the magnetic and topological properties of these exciting materials. An introduction is first given to the heterostructure growth by molecular beam epitaxy and suitable structural, electronic, and magnetic characterization techniques. Going beyond transition-metal-doped and undoped TI heterostructures, examples of heterostructures are discussed, including rare-earth-doped TIs, magnetic insulators, and antiferromagnets, which lead to exotic phenomena such as skyrmions and exchange bias. Finally, an outlook on novel heterostructures such as intrinsic magnetic TIs and systems including 2D materials is given.
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Affiliation(s)
- Jieyi Liu
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Thorsten Hesjedal
- Clarendon Laboratory, Department of Physics University of Oxford, Parks Road, Oxford, OX1 3PU, UK
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15
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Peng X, Liang H, Dong X, Yang H, Wang X, Qiao L, Li J, Wang C, Han J, Wang Q, Chen G, Xiao W. Epitaxial growth of Bi(110) and Bi 2Se 3thin films on a ferromagnetic insulator substrate of Cr 2Ge 2Te 6. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:415001. [PMID: 34271559 DOI: 10.1088/1361-648x/ac1535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 07/16/2021] [Indexed: 06/13/2023]
Abstract
When a topological insulator (TI) is brought to the proximity of a ferromagnetic insulator (FMI), the breaking of the time-reversal symmetry may give rise to quantum anomalous Hall effect (QAHE). The physical properties of such TI-FMI systems are greatly affected by the interfacial structures of the components. Here, we report the growth and structural properties of Bi(110) and Bi2Se3thin films on a FMI of Cr2Ge2Te6(CGT) substrate by scanning tunneling microscopy. We observed various defects and impurities on the CGT surfaces, which serve as the preferential sites for initial nucleation and epitaxial growth of Bi(110) thin films. The exposure of the as-grown Bi(110) thin films to Se vapor leads to the formation of polycrystalline Bi2Se3thin films with randomly distributed holes. The structure and composition of the as-prepared Bi2Se3thin films were further confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy. Our work shows that the quality of the CGT crystals is vital for the growth of high-quality TIs on CGT substrates for QAHE.
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Affiliation(s)
- Xianglin Peng
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Hui Liang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xu Dong
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Huixia Yang
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Xiangzhuo Wang
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Lu Qiao
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Ji Li
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Chang Wang
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Junfeng Han
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Qinsheng Wang
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Genfu Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan 523808, People's Republic of China
| | - Wende Xiao
- Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
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16
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Bhattacharyya S, Akhgar G, Gebert M, Karel J, Edmonds MT, Fuhrer MS. Recent Progress in Proximity Coupling of Magnetism to Topological Insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007795. [PMID: 34185344 DOI: 10.1002/adma.202007795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/11/2021] [Indexed: 05/08/2023]
Abstract
Inducing long-range magnetic order in 3D topological insulators can gap the Dirac-like metallic surface states, leading to exotic new phases such as the quantum anomalous Hall effect or the axion insulator state. These magnetic topological phases can host robust, dissipationless charge and spin currents or unique magnetoelectric behavior, which can be exploited in low-energy electronics and spintronics applications. Although several different strategies have been successfully implemented to realize these states, to date these phenomena have been confined to temperatures below a few Kelvin. This review focuses on one strategy: inducing magnetic order in topological insulators by proximity of magnetic materials, which has the capability for room temperature operation, unlocking the potential of magnetic topological phases for applications. The unique advantages of this strategy, the important physical mechanisms facilitating magnetic proximity effect, and the recent progress to achieve, understand, and harness proximity-coupled magnetic order in topological insulators are discussed. Some emerging new phenomena and applications enabled by proximity coupling of magnetism and topological materials, such as skyrmions and the topological Hall effect, are also highlighted, and the authors conclude with an outlook on remaining challenges and opportunities in the field.
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Affiliation(s)
- Semonti Bhattacharyya
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
| | - Golrokh Akhgar
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
| | - Matthew Gebert
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
| | - Julie Karel
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
- Department of Materials Science and Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - Mark T Edmonds
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
| | - Michael S Fuhrer
- School of Physics and Astronomy, Monash University, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria, 3800, Australia
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17
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Sierra JF, Fabian J, Kawakami RK, Roche S, Valenzuela SO. Van der Waals heterostructures for spintronics and opto-spintronics. NATURE NANOTECHNOLOGY 2021; 16:856-868. [PMID: 34282312 DOI: 10.1038/s41565-021-00936-x] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 06/03/2021] [Indexed: 06/13/2023]
Abstract
The large variety of 2D materials and their co-integration in van der Waals heterostructures enable innovative device engineering. In addition, their atomically thin nature promotes the design of artificial materials by proximity effects that originate from short-range interactions. Such a designer approach is particularly compelling for spintronics, which typically harnesses functionalities from thin layers of magnetic and non-magnetic materials and the interfaces between them. Here we provide an overview of recent progress in 2D spintronics and opto-spintronics using van der Waals heterostructures. After an introduction to the forefront of spin transport research, we highlight the unique spin-related phenomena arising from spin-orbit and magnetic proximity effects. We further describe the ability to create multifunctional hybrid heterostructures based on van der Waals materials, combining spin, valley and excitonic degrees of freedom. We end with an outlook on perspectives and challenges for the design and production of ultracompact all-2D spin devices and their potential applications in conventional and quantum technologies.
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Affiliation(s)
- Juan F Sierra
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, Regensburg, Germany
| | | | - Stephan Roche
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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18
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Yao X, Yi HT, Jain D, Han MG, Oh S. Spacer-Layer-Tunable Magnetism and High-Field Topological Hall Effect in Topological Insulator Heterostructures. NANO LETTERS 2021; 21:5914-5919. [PMID: 34265206 DOI: 10.1021/acs.nanolett.1c00668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Controlling magnetic order in magnetic topological insulators (MTIs) is a key to developing spintronic applications with MTIs and is commonly achieved by changing the magnetic doping concentration, which inevitably affects the spin-orbit coupling strength and the topological properties. Here, we demonstrate tunable magnetic properties in topological heterostructures over a wide range, from a ferromagnetic phase with a Curie temperature of around 100 K all the way to a paramagnetic phase, while keeping the overall chemical composition the same, by controlling the thickness of nonmagnetic spacer layers between two atomically thin magnetic layers. This work showcases that spacer-layer control is a powerful tool to manipulate magneto-topological functionalities in MTI heterostructures. Furthermore, the interaction between the MTI and the Cr2O3 buffer layers also leads to a robust topological Hall effect surviving up to a record-high 6 T of magnetic field, shedding light on the critical role of interfacial layers in thin-film topological materials.
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Affiliation(s)
- Xiong Yao
- Center for Quantum Materials Synthesis and Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Hee Taek Yi
- Center for Quantum Materials Synthesis and Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Deepti Jain
- Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Myung-Geun Han
- Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Seongshik Oh
- Center for Quantum Materials Synthesis and Department of Physics & Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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19
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Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals. Nat Commun 2021; 12:2088. [PMID: 33828083 PMCID: PMC8027870 DOI: 10.1038/s41467-021-22412-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 03/15/2021] [Indexed: 12/04/2022] Open
Abstract
The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery. Systems where both time-reversal symmetry and inversion symmetry are broken can exhibit a magneto-chiral effect; however, this is usually weak. Here, Lan et al demonstrate a significantly enhanced excitonic magnetochiral effect in twisted bilayer tungsten disulphide on a ferromagnetic substrate.
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20
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Li P, Ding J, Zhang SSL, Kally J, Pillsbury T, Heinonen OG, Rimal G, Bi C, DeMann A, Field SB, Wang W, Tang J, Jiang JS, Hoffmann A, Samarth N, Wu M. Topological Hall Effect in a Topological Insulator Interfaced with a Magnetic Insulator. NANO LETTERS 2021; 21:84-90. [PMID: 33356300 DOI: 10.1021/acs.nanolett.0c03195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A topological insulator (TI) interfaced with a magnetic insulator (MI) may host an anomalous Hall effect (AHE), a quantum AHE, and a topological Hall effect (THE). Recent studies, however, suggest that coexisting magnetic phases in TI/MI heterostructures may result in an AHE-associated response that resembles a THE but in fact is not. This Letter reports a genuine THE in a TI/MI structure that has only one magnetic phase. The structure shows a THE in the temperature range of T = 2-3 K and an AHE at T = 80-300 K. Over T = 3-80 K, the two effects coexist but show opposite temperature dependencies. Control measurements, calculations, and simulations together suggest that the observed THE originates from skyrmions, rather than the coexistence of two AHE responses. The skyrmions are formed due to a Dzyaloshinskii-Moriya interaction (DMI) at the interface; the DMI strength estimated is substantially higher than that in heavy metal-based systems.
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Affiliation(s)
- Peng Li
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Jinjun Ding
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Steven S-L Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - James Kally
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Timothy Pillsbury
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Olle G Heinonen
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Gaurab Rimal
- Department of Physics & Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Chong Bi
- Department of Physics, University of Arizona, Tucson, Arizona 85721, United States
| | - August DeMann
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Stuart B Field
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Weigang Wang
- Department of Physics, University of Arizona, Tucson, Arizona 85721, United States
| | - Jinke Tang
- Department of Physics & Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Jidong Samuel Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801, United States
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
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21
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Figueroa AI, Bonell F, Cuxart MG, Valvidares M, Gargiani P, van der Laan G, Mugarza A, Valenzuela SO. Absence of Magnetic Proximity Effect at the Interface of Bi_{2}Se_{3} and (Bi,Sb)_{2}Te_{3} with EuS. PHYSICAL REVIEW LETTERS 2020; 125:226801. [PMID: 33315425 DOI: 10.1103/physrevlett.125.226801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 09/02/2020] [Accepted: 10/16/2020] [Indexed: 06/12/2023]
Abstract
We performed x-ray magnetic circular dichroism (XMCD) measurements on heterostructures comprising topological insulators (TIs) of the (Bi,Sb)_{2}(Se,Te)_{3} family and the magnetic insulator EuS. XMCD measurements allow us to investigate element-selective magnetic proximity effects at the very TI/EuS interface. A systematic analysis reveals that there is neither significant induced magnetism within the TI nor an enhancement of the Eu magnetic moment at such interface. The induced magnetic moments in Bi, Sb, Te, and Se sites are lower than the estimated detection limit of the XMCD measurements of ∼10^{-3} μ_{B}/at.
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Affiliation(s)
- A I Figueroa
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - F Bonell
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - M G Cuxart
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Universitat Autònoma de Barcelona (UAB), Bellaterra 08193, Spain
| | - M Valvidares
- ALBA Synchrotron Light Source, Barcelona 08290, Spain
| | - P Gargiani
- ALBA Synchrotron Light Source, Barcelona 08290, Spain
| | - G van der Laan
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - A Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
| | - S O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
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22
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Yang CY, Pan L, Grutter AJ, Wang H, Che X, He QL, Wu Y, Gilbert DA, Shafer P, Arenholz E, Wu H, Yin G, Deng P, Borchers JA, Ratcliff W, Wang KL. Termination switching of antiferromagnetic proximity effect in topological insulator. SCIENCE ADVANCES 2020; 6:eaaz8463. [PMID: 32851159 PMCID: PMC7423361 DOI: 10.1126/sciadv.aaz8463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 06/26/2020] [Indexed: 05/23/2023]
Abstract
This work reports the ferromagnetism of topological insulator, (Bi,Sb)2Te3 (BST), with a Curie temperature of approximately 120 K induced by magnetic proximity effect (MPE) of an antiferromagnetic CrSe. The MPE was shown to be highly dependent on the stacking order of the heterostructure, as well as the interface symmetry: Growing CrSe on top of BST results in induced ferromagnetism, while growing BST on CrSe yielded no evidence of an MPE. Cr-termination in the former case leads to double-exchange interactions between Cr3+ surface states and Cr2+ bulk states. This Cr3+-Cr2+ exchange stabilizes the ferromagnetic order localized at the interface and magnetically polarizes the BST Sb band. In contrast, Se-termination at the CrSe/BST interface yields no detectable MPE. These results directly confirm the MPE in BST films and provide critical insights into the sensitivity of the surface state.
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Affiliation(s)
- Chao-Yao Yang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Alexander J. Grutter
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA
| | - Haiying Wang
- College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China
| | - Xiaoyu Che
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Qing Lin He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Yingying Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Dustin A. Gilbert
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Cornell High Energy Synchrotron Source, Ithaca, NY 14853, USA
| | - Hao Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Gen Yin
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Peng Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
| | - Julie Ann Borchers
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA
| | - William Ratcliff
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Kang L. Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA
- Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA
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23
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Liu T, Kally J, Pillsbury T, Liu C, Chang H, Ding J, Cheng Y, Hilse M, Engel-Herbert R, Richardella A, Samarth N, Wu M. Changes of Magnetism in a Magnetic Insulator due to Proximity to a Topological Insulator. PHYSICAL REVIEW LETTERS 2020; 125:017204. [PMID: 32678653 DOI: 10.1103/physrevlett.125.017204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 04/13/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
We report the modification of magnetism in a magnetic insulator Y_{3}Fe_{5}O_{12} thin film by topological surface states (TSS) in an adjacent topological insulator Bi_{2}Se_{3} thin film. Ferromagnetic resonance measurements show that the TSS in Bi_{2}Se_{3} produces a perpendicular magnetic anisotropy, results in a decrease in the gyromagnetic ratio, and enhances the damping in Y_{3}Fe_{5}O_{12}. Such TSS-induced changes become more pronounced as the temperature decreases from 300 to 50 K. These results suggest a completely new approach for control of magnetism in magnetic thin films.
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Affiliation(s)
- Tao Liu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - James Kally
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Timothy Pillsbury
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Chuanpu Liu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Houchen Chang
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Jinjun Ding
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Yang Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Maria Hilse
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Roman Engel-Herbert
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Anthony Richardella
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Nitin Samarth
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
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24
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Ng SM, Wang H, Liu Y, Wong HF, Yau HM, Suen CH, Wu ZH, Leung CW, Dai JY. High-Temperature Anomalous Hall Effect in a Transition Metal Dichalcogenide Ferromagnetic Insulator Heterostructure. ACS NANO 2020; 14:7077-7084. [PMID: 32407078 DOI: 10.1021/acsnano.0c01815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Integration of transition metal dichalcogenides (TMDs) on ferromagnetic materials (FM) may yield fascinating physics and promise for electronics and spintronic applications. In this work, high-temperature anomalous Hall effect (AHE) in the TMD ZrTe2 thin film using a heterostructure approach by depositing it on a ferrimagnetic insulator YIG (Y3Fe5O12, yttrium iron garnet) is demonstrated. In this heterostructure, significant anomalous Hall effect can be observed at temperatures up to at least 400 K, which is a record high temperature for the observation of AHE in TMDs, and the large RAHE is more than 1 order of magnitude larger than those previously reported values in topological insulators or TMD-based heterostructures. A complicated interface with additional ZrO2 and amorphous YIG layers is actually observed between ZrTe2 and YIG. The magnetization of interfacial reaction-induced ZrO2 and YIG is believed to play a crucial role in the induced high-temperature AHE in the ZrTe2. These results present a promising system for the spintronic device applications, and it may shed light on the designing approach to introduce magnetism to TMDs at room temperature.
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Affiliation(s)
- Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Huichao Wang
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
- School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yukuai Liu
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Hon Fai Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Hei Man Yau
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Chun Hung Suen
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Ze Han Wu
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University, 999077, Hong Kong, P.R. China
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25
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Pan L, Liu X, He QL, Stern A, Yin G, Che X, Shao Q, Zhang P, Deng P, Yang CY, Casas B, Choi ES, Xia J, Kou X, Wang KL. Probing the low-temperature limit of the quantum anomalous Hall effect. SCIENCE ADVANCES 2020; 6:eaaz3595. [PMID: 32596443 PMCID: PMC7299611 DOI: 10.1126/sciadv.aaz3595] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 05/05/2020] [Indexed: 05/23/2023]
Abstract
Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)2Te3 systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.
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Affiliation(s)
- Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xiaoyang Liu
- School of Information Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Qing Lin He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Alexander Stern
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Gen Yin
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xiaoyu Che
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Qiming Shao
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peng Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Chao-Yao Yang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Brian Casas
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
| | - Eun Sang Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-3706, USA
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Kang L. Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA
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26
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Ali M Keshtan M, Esmaeilzadeh M. Topological spintronics in a polyacetylene molecule device. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:345302. [PMID: 32209751 DOI: 10.1088/1361-648x/ab832a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 03/25/2020] [Indexed: 06/10/2023]
Abstract
Using the Su-Schrieffer-Heeger Hamiltonian and exploiting the Green's function method in the framework of the Landauer-Büttiker formalism, the topological and spin dependent electron transport properties of a trans polyacetylene molecule are studied. It is found that molecules with the intracell single carbon-carbon bonding and the even number of monomers in their chains have two edge states and possess topological properties though their Hamiltonians do not respect the chiral symmetry. A perpendicular exchange magnetic field and two perpendicular and transverse electric fields are used to induce and manipulate the quantum spin dependent electron transport properties. The exchange field induces the spin polarization in different electron energy regions which are expanded by stronger exchange fields. Therefore this proposed device works as a perfect spin filter. The spin polarization can be manipulated by applying the perpendicular electric field and remains robust against the transverse electric field variations.
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Affiliation(s)
- M Ali M Keshtan
- Department of physics, Iran University of Science and Technology, Narmak, Tehran 16844, Iran
| | - Mahdi Esmaeilzadeh
- Department of physics, Iran University of Science and Technology, Narmak, Tehran 16844, Iran
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27
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Chen P, Zhang Y, Yao Q, Tian F, Li L, Qi Z, Liu X, Liao L, Song C, Wang J, Xia J, Li G, Burn DM, van der Laan G, Hesjedal T, Zhang S, Kou X. Tailoring the Hybrid Anomalous Hall Response in Engineered Magnetic Topological Insulator Heterostructures. NANO LETTERS 2020; 20:1731-1737. [PMID: 32013439 DOI: 10.1021/acs.nanolett.9b04932] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Engineering the anomalous Hall effect (AHE) is the key to manipulate the magnetic orders in the emerging magnetic topological insulators (MTIs). In this letter, we synthesize the epitaxial Bi2Te3/MnTe magnetic heterostructures and observe pronounced AHE signals from both layers combined together. The evolution of the resulting hybrid AHE intensity with the top Bi2Te3 layer thickness manifests the presence of an intrinsic ferromagnetic phase induced by the topological surface states at the heterolayer interface. More importantly, by doping the Bi2Te3 layer with Sb, we are able to manipulate the sign of the Berry phase-associated AHE component. Our results demonstrate the unparalleled advantages of MTI heterostructures over magnetically doped TI counterparts in which the tunability of the AHE response can be greatly enhanced. This in turn unveils a new avenue for MTI heterostructure-based multifunctional applications.
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Affiliation(s)
| | | | | | | | | | | | | | - Liyang Liao
- Key Lab Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Cheng Song
- Key Lab Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Jingyuan Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | | | - David M Burn
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Gerrit van der Laan
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Thorsten Hesjedal
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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28
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Zhang S, Wang R, Wang X, Wei B, Chen B, Wang H, Shi G, Wang F, Jia B, Ouyang Y, Xie F, Fei F, Zhang M, Wang X, Wu D, Wan X, Song F, Zhang H, Wang B. Experimental Observation of the Gate-Controlled Reversal of the Anomalous Hall Effect in the Intrinsic Magnetic Topological Insulator MnBi 2Te 4 Device. NANO LETTERS 2020; 20:709-714. [PMID: 31838853 DOI: 10.1021/acs.nanolett.9b04555] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Magnetic topological insulator, a platform for realizing quantum anomalous Hall effect, axion state, and other novel quantum transport phenomena, has attracted a lot of interest. Recently, it is proposed that MnBi2Te4 is an intrinsic magnetic topological insulator, which may overcome the disadvantages in the magnetic doped topological insulator, such as disorder. Here we report on the gate-reserved anomalous Hall effect (AHE) in the MnBi2Te4 thin film. By tuning the Fermi level using the top/bottom gate, the AHE loop gradually decreases to zero and the sign is reversed. The positive AHE exhibits distinct coercive fields compared with the negative AHE. It reaches a maximum inside the gap of the Dirac cone, and its amplitude exhibits a linear scaling with the longitudinal conductance. The positive AHE is attributed to the competition of the intrinsic Berry curvature and the extrinsic skew scattering. Its gate-controlled switching contributes a scheme for the topological spin field-effect transistors.
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Affiliation(s)
- Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Rui Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
- Department of Physics and Astronomy , Shanghai Jiao Tong University , Shanghai 200240 , China
| | - Xuepeng Wang
- 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
| | - Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Huaiqiang Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Gang Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Feng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Bin Jia
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Yiping Ouyang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Faji Xie
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Minhao Zhang
- 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, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures , 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
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , 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
| | - Baigeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics , Nanjing University , Nanjing 210093 , China
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29
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Balram AC, Flensberg K, Paaske J, Rudner MS. Current-Induced Gap Opening in Interacting Topological Insulator Surfaces. PHYSICAL REVIEW LETTERS 2019; 123:246803. [PMID: 31922820 DOI: 10.1103/physrevlett.123.246803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Indexed: 06/10/2023]
Abstract
Two-dimensional topological insulators (TIs) host gapless helical edge states that are predicted to support a quantized two-terminal conductance. Quantization is protected by time-reversal symmetry, which forbids elastic backscattering. Paradoxically, the current-carrying state itself breaks the time-reversal symmetry that protects it. Here we show that the combination of electron-electron interactions and momentum-dependent spin polarization in helical edge states gives rise to feedback through which an applied current opens a gap in the edge state dispersion, thereby breaking the protection against elastic backscattering. Current-induced gap opening is manifested via a nonlinear contribution to the system's I-V characteristic, which persists down to zero temperature. We discuss prospects for realizations in recently discovered large bulk band gap TIs, and an analogous current-induced gap opening mechanism for the surface states of three-dimensional TIs.
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Affiliation(s)
- Ajit C Balram
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- The Institute of Mathematical Sciences, HBNI, CIT Campus, Chennai 600113, India
| | - Karsten Flensberg
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jens Paaske
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Mark S Rudner
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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30
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Xu Y, Chen YR, Wang J, Liu JF, Ma Z. Quantized Field-Effect Tunneling between Topological Edge or Interface States. PHYSICAL REVIEW LETTERS 2019; 123:206801. [PMID: 31809113 DOI: 10.1103/physrevlett.123.206801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 09/08/2019] [Indexed: 06/10/2023]
Abstract
We study the tunneling through a two-dimensional topological insulator with topologically protected edge states. It is shown that the tunneling probability can be quantized in a broad parameter range, 0 or 1, tuned by an applied transverse electric field. Based on this field-effect tunneling, we propose two types of topological transistors based on helical edge or interface states of quantum spin Hall insulators separately. The quantized tunneling conductance is obtained and shown to be robust against nonmagnetic disorders. Usually, the topological transition is necessary in the operation of topological transistors. These findings provide a new strategy for the design of topological transistors without topological transitions.
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Affiliation(s)
- Yong Xu
- School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yan-Ru Chen
- School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jun Wang
- Department of Physics, Southeast University, Nanjing 210096, China
| | - Jun-Feng Liu
- School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhongshui Ma
- School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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31
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Kumar R, Samantaray B, Hossain Z. Ferromagnetic resonance studies of strain tuned Bi:YIG films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:435802. [PMID: 31265999 DOI: 10.1088/1361-648x/ab2e93] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bismuth-doped Yttrium iron garnet (Bi:YIG) thin films known for large magneto-optical activity with low losses still need to get probed for its magnetization dynamics. We demonstrate a controlled tuning of magnetocrystalline anisotropy in Bi-doped Y3Fe5O12 (Bi:YIG) films of high crystalline quality using growth induced epitaxial strain on [1 1 1]-oriented Gd3Ga5O12 (GGG) substrate. We optimize a growth protocol to get thick highly-strained epitaxial films showing large magneto-crystalline anisotropy, compare to thin films prepared using a different protocol. Ferromagnetic resonance measurements establish a linear dependence of the out-of-plane uniaxial anisotropy on the strain induced rhombohedral distortion of Bi:YIG lattice. Interestingly, the enhancement in the magnetoelastic constant due to an optimum substitution of Bi3+ ions with strong spin orbit coupling does not strongly affect the precessional damping (∼[Formula: see text]). Large magneto-optical activity, reasonably low damping, large magnetocrystalline anisotropy and large magnetoelastic coupling in Bi:YIG are the properties that may help Bi:YIG emerge as a possible material for photo-magnonics and other spintronics applications.
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Affiliation(s)
- Ravinder Kumar
- Condensed Matter-Low Dimensional Systems Laboratory, Department of Physics, Indian Institute of Technology (IIT) Kanpur-208016, India
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32
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Liao L, Chen P, Kou X, Pan F, Song C. Tuning the magnetotransport behavior of topological insulator with a transition-metal oxide layer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:405001. [PMID: 31272092 DOI: 10.1088/1361-648x/ab2f53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The interaction between topological insulator (TI) and its adjacent magnetic layer serves as a basis for exploring the device application of TI. Here we investigate the modulation of the magnetotransport behavior of Bi2Te3 TI with a transition-metal oxide layer NiO. It is found that the weak-antilocalization effect is absent at low magnetic fields and the magnetoresistance ratio decreases monotonically with increasing the NiO growth temperature from 300 to 473 K, indicating the suppression of the topological surface states of Bi2Te3. Such behaviors are attributed to the decomposition of NiO and the concomitant formation of magnetic impurities at the Bi2Te3/NiO interface. Differently, the weak-antilocalization shows no significant weakening with the growth of Cr2O3 top layer, due to its better chemical stability. Our observation would be significant for the material selection for the device integration of TI.
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Affiliation(s)
- Liyang Liao
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China
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33
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Li P, Kally J, Zhang SSL, Pillsbury T, Ding J, Csaba G, Ding J, Jiang JS, Liu Y, Sinclair R, Bi C, DeMann A, Rimal G, Zhang W, Field SB, Tang J, Wang W, Heinonen OG, Novosad V, Hoffmann A, Samarth N, Wu M. Magnetization switching using topological surface states. SCIENCE ADVANCES 2019; 5:eaaw3415. [PMID: 31497642 PMCID: PMC6716955 DOI: 10.1126/sciadv.aaw3415] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 07/31/2019] [Indexed: 05/19/2023]
Abstract
Topological surface states (TSSs) in a topological insulator are expected to be able to produce a spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is conductive because it can completely suppress the TSSs, but it should be present if the ferromagnet is insulating. This study reports TSS-induced switching in a bilayer consisting of a topological insulator Bi2Se3 and an insulating ferromagnet BaFe12O19. A charge current in Bi2Se3 can switch the magnetization in BaFe12O19 up and down. When the magnetization is switched by a field, a current in Bi2Se3 can reduce the switching field by ~4000 Oe. The switching efficiency at 3 K is 300 times higher than at room temperature; it is ~30 times higher than in Pt/BaFe12O19. These strong effects originate from the presence of more pronounced TSSs at low temperatures due to enhanced surface conductivity and reduced bulk conductivity.
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Affiliation(s)
- Peng Li
- Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
| | - James Kally
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Steven S.-L. Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Timothy Pillsbury
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Jinjun Ding
- Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
| | - Gyorgy Csaba
- Faculty of Information Technology and Bionics, Pazmany Peter Catholic University, Budapest, Hungary
| | - Junjia Ding
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - J. S. Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yunzhi Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Robert Sinclair
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chong Bi
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - August DeMann
- Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
| | - Gaurab Rimal
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
| | - Wei Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
- Department of Physics, Oakland University, Rochester, MI 48309, USA
| | - Stuart B. Field
- Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
| | - Jinke Tang
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
| | - Weigang Wang
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - Olle G. Heinonen
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Valentine Novosad
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
- Corresponding author.
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34
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Yao X, Gao B, Han MG, Jain D, Moon J, Kim JW, Zhu Y, Cheong SW, Oh S. Record High-Proximity-Induced Anomalous Hall Effect in (Bi xSb 1-x) 2Te 3 Thin Film Grown on CrGeTe 3 Substrate. NANO LETTERS 2019; 19:4567-4573. [PMID: 31185718 DOI: 10.1021/acs.nanolett.9b01495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Quantum anomalous Hall effect (QAHE) can only be realized at extremely low temperatures in magnetically doped topological insulators (TIs) due to limitations inherent with the doping process. In an effort to boost the quantization temperature of QAHE, the magnetic proximity effect in magnetic insulator/TI heterostructures has been extensively investigated. However, the observed anomalous Hall resistance has never been more than several ohms, presumably owing to the interfacial disorders caused by the structural and chemical mismatch. Here, we show that, by growing (BixSb1-x)2Te3 (BST) thin films on structurally and chemically well-matched, ferromagnetic-insulating CrGeTe3 (CGT) substrates, the proximity-induced anomalous Hall resistance can be enhanced by more than an order of magnitude. This sheds light on the importance of structural and chemical matches for magnetic insulator/TI proximity systems.
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Affiliation(s)
- Xiong Yao
- Center for Quantum Materials Synthesis and Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Bin Gao
- Department of Physics and Astronomy , Rice University , Houston , Texas 77005 , United States
| | - Myung-Geun Han
- Condensed Matter Physics and Materials Science , Brookhaven National Laboratory , Upton , New York 11973 , United States
| | - Deepti Jain
- Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Jisoo Moon
- Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Jae Wook Kim
- Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science , Brookhaven National Laboratory , Upton , New York 11973 , United States
| | - Sang-Wook Cheong
- Center for Quantum Materials Synthesis and Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Seongshik Oh
- Center for Quantum Materials Synthesis and Department of Physics and Astronomy , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854 , United States
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Mogi M, Nakajima T, Ukleev V, Tsukazaki A, Yoshimi R, Kawamura M, Takahashi KS, Hanashima T, Kakurai K, Arima TH, Kawasaki M, Tokura Y. Large Anomalous Hall Effect in Topological Insulators with Proximitized Ferromagnetic Insulators. PHYSICAL REVIEW LETTERS 2019; 123:016804. [PMID: 31386415 DOI: 10.1103/physrevlett.123.016804] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/24/2019] [Indexed: 06/10/2023]
Abstract
We report a proximity-driven large anomalous Hall effect in all-telluride heterostructures consisting of the ferromagnetic insulator Cr_{2}Ge_{2}Te_{6} and topological insulator (Bi,Sb)_{2}Te_{3}. Despite small magnetization in the (Bi,Sb)_{2}Te_{3} layer, the anomalous Hall conductivity reaches a large value of 0.2e^{2}/h in accord with a ferromagnetic response of the Cr_{2}Ge_{2}Te_{6}. The results show that the exchange coupling between the surface state of the topological insulator and the proximitized Cr_{2}Ge_{2}Te_{6} layer is effective and strong enough to open the sizable exchange gap in the surface state.
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Affiliation(s)
- Masataka Mogi
- Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Taro Nakajima
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Victor Ukleev
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), CH-5232, Villigen, Switzerland
| | - Atsushi Tsukazaki
- Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Ryutaro Yoshimi
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Minoru Kawamura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Kei S Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075, Japan
| | - Takayasu Hanashima
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075, Japan
| | - Kazuhisa Kakurai
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Taka-Hisa Arima
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Masashi Kawasaki
- Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Tokyo College, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
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36
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Wang F, Xiao D, Yuan W, Jiang J, Zhao YF, Zhang L, Yao Y, Liu W, Zhang Z, Liu C, Shi J, Han W, Chan MHW, Samarth N, Chang CZ. Observation of Interfacial Antiferromagnetic Coupling between Magnetic Topological Insulator and Antiferromagnetic Insulator. NANO LETTERS 2019; 19:2945-2952. [PMID: 30942075 DOI: 10.1021/acs.nanolett.9b00027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Inducing magnetic orders in a topological insulator (TI) to break its time reversal symmetry has been predicted to reveal many exotic topological quantum phenomena. The manipulation of magnetic orders in a TI layer can play a key role in harnessing these quantum phenomena toward technological applications. Here we fabricated a thin magnetic TI film on an antiferromagnetic (AFM) insulator Cr2O3 layer and found that the magnetic moments of the magnetic TI layer and the surface spins of the Cr2O3 layers favor interfacial AFM coupling. Field cooling studies show a crossover from negative to positive exchange bias clarifying the competition between the interfacial AFM coupling energy and the Zeeman energy in the AFM insulator layer. The interfacial exchange coupling also enhances the Curie temperature of the magnetic TI layer. The unique interfacial AFM alignment in magnetic TI on AFM insulator heterostructures opens a new route toward manipulating the interplay between topological states and magnetic orders in spin-engineered heterostructures, facilitating the exploration of proof-of-concept TI-based spintronic and electronic devices with multifunctionality and low power consumption.
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Affiliation(s)
- Fei Wang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Di Xiao
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Wei Yuan
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- Department of Physics , University of California , Riverside , California 92521 , United States
| | - Jue Jiang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Yi-Fan Zhao
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ling Zhang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Yunyan Yao
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Wei Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Zhidong Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Chaoxing Liu
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Jing Shi
- Department of Physics , University of California , Riverside , California 92521 , United States
| | - Wei Han
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100871 , China
| | - Moses H W Chan
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Nitin Samarth
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Cui-Zu Chang
- Department of Physics , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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37
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Hou Y, Kim J, Wu R. Magnetizing topological surface states of Bi 2Se 3 with a CrI 3 monolayer. SCIENCE ADVANCES 2019; 5:eaaw1874. [PMID: 31172028 PMCID: PMC6544448 DOI: 10.1126/sciadv.aaw1874] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/23/2019] [Indexed: 05/23/2023]
Abstract
To magnetize surfaces of topological insulators without damaging their topological feature is a crucial step for the realization of the quantum anomalous Hall effect (QAHE) and remains as a challenging task. Through density functional calculations, we found that adsorption of a semiconducting two-dimensional van der Waals (2D-vdW) ferromagnetic CrI3 monolayer can create a sizable spin splitting at the Dirac point of the topological surface states of Bi2Se3 films. Furthermore, general rules that connect different quantum and topological parameters are established through model analyses. This work provides a useful guideline for the realization of QAHE at high temperatures in heterostructures of 2D-vdW magnetic monolayers and topological insulators.
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Affiliation(s)
- Yusheng Hou
- Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA
| | - Jeongwoo Kim
- Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA
- Department of Physics, Incheon National University, Incheon 22012, Korea
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA
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38
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Hou Y, Wu R. Axion Insulator State in a Ferromagnet/Topological Insulator/Antiferromagnet Heterostructure. NANO LETTERS 2019; 19:2472-2477. [PMID: 30868887 DOI: 10.1021/acs.nanolett.9b00047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We propose the use of ferromagnetic insulator MnBi2Se4/Bi2Se3/antiferromagnetic insulator Mn2Bi2Se5 heterostructures for the realization of the axion insulator state. Importantly, the axion insulator state in such heterostructures only depends on the magnetization of the ferromagnetic insulator and, hence, can be observed in a wide range of external magnetic fields. Using density functional calculations and model Hamiltonian simulations, we find that the top and bottom surfaces have opposite half-quantum Hall conductances, [Formula: see text] and [Formula: see text], with a sizable global spin gap of 5.1 meV opened for the topological surface states of Bi2Se3. Our work provides a new strategy for the search of axion insulators by using van der Waals antiferromagnetic insulators along with three-dimensional topological insulators.
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Affiliation(s)
- Yusheng Hou
- Department of Physics and Astronomy , University of California , Irvine , California 92697-4575 , United States
| | - Ruqian Wu
- Department of Physics and Astronomy , University of California , Irvine , California 92697-4575 , United States
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39
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Sohn C, Skoropata E, Choi Y, Gao X, Rastogi A, Huon A, McGuire MA, Nuckols L, Zhang Y, Freeland JW, Haskel D, Lee HN. Room-Temperature Ferromagnetic Insulating State in Cation-Ordered Double-Perovskite Sr 2 Fe 1+ x Re 1- x O 6 Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805389. [PMID: 30489665 DOI: 10.1002/adma.201805389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/23/2018] [Indexed: 06/09/2023]
Abstract
Ferromagnetic insulators (FMIs) are one of the most important components in developing dissipationless electronic and spintronic devices. However, FMIs are innately rare to find in nature as ferromagnetism generally accompanies metallicity. Here, novel room-temperature FMI films that are epitaxially synthesized by deliberate control of the ratio between two B-site cations in the double perovskite Sr2 Fe1+ x Re1- x O6 (-0.2 ≤ x ≤ 0.2) are reported. In contrast to the known FM metallic phase in stoichiometric Sr2 FeReO6 , an FMI state with a high Curie temperature (Tc ≈ 400 K) and a large saturation magnetization (MS ≈ 1.8 µB f.u.-1 ) is found in highly cation-ordered Fe-rich phases. The stabilization of the FMI state is attributed to the formation of extra Fe3+ Fe3+ and Fe3+ Re6+ bonding states, which originate from the relatively excess Fe ions owing to the deficiency in Re ions. The emerging FMI state created by controlling cations in the oxide double perovskites opens the door to developing novel oxide quantum materials and spintronic devices.
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Affiliation(s)
- Changhee Sohn
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Elizabeth Skoropata
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Xiang Gao
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Ankur Rastogi
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Amanda Huon
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Department of Materials Science & Engineering, Drexel University, Philadelphia, PA, 19104, USA
| | - Michael A McGuire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Lauren Nuckols
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Yanwen Zhang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - John W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Daniel Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Ho Nyung Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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40
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Shao Q, Tang C, Yu G, Navabi A, Wu H, He C, Li J, Upadhyaya P, Zhang P, Razavi SA, He QL, Liu Y, Yang P, Kim SK, Zheng C, Liu Y, Pan L, Lake RK, Han X, Tserkovnyak Y, Shi J, Wang KL. Role of dimensional crossover on spin-orbit torque efficiency in magnetic insulator thin films. Nat Commun 2018; 9:3612. [PMID: 30190509 PMCID: PMC6127239 DOI: 10.1038/s41467-018-06059-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 08/03/2018] [Indexed: 12/04/2022] Open
Abstract
Magnetic insulators (MIs) attract tremendous interest for spintronic applications due to low Gilbert damping and the absence of Ohmic loss. Spin-orbit torques (SOTs) on MIs are more intriguing than magnetic metals since SOTs cannot be transferred to MIs through direct injection of electron spins. Understanding of SOTs on MIs remains elusive, especially how SOTs scale with the MI film thickness. Here, we observe the critical role of dimensionality on the SOT efficiency by studying the MI layer thickness-dependent SOT efficiency in tungsten/thulium iron garnet (W/TmIG) bilayers. We show that the TmIG thin film evolves from two-dimensional to three-dimensional magnetic phase transitions as the thickness increases. We report the significant enhancement of the measured SOT efficiency as the TmIG thickness increases, which is attributed to the increase of the magnetic moment density. We demonstrate the current-induced SOT switching in the W/TmIG bilayers with a TmIG thickness up to 15 nm. The spin-orbit torque (SOT) induced magnetic switching makes metal/magnetic insulators bilayers preferred in the energy efficient spintronic applications. Here the authors show SOT switching in W/TmIG bilayers and reveal the dimension crossover of SOT as a function of TmIG thickness.
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Affiliation(s)
- Qiming Shao
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Chi Tang
- Department of Physics & Astronomy, University of California, Riverside, CA, 92521, USA
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. .,Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Aryan Navabi
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Hao Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Congli He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Junxue Li
- Department of Physics & Astronomy, University of California, Riverside, CA, 92521, USA
| | - Pramey Upadhyaya
- Department of Physics & Astronomy, University of California, Los Angeles, CA, 90095, USA
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Seyed Armin Razavi
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Qing Lin He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Yawen Liu
- Department of Physics & Astronomy, University of California, Riverside, CA, 92521, USA
| | - Pei Yang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA.,York-Nanjing Joint Center for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Se Kwon Kim
- Department of Physics & Astronomy, University of California, Los Angeles, CA, 90095, USA
| | - Cheng Zheng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Yizhou Liu
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521, USA
| | - Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Roger K Lake
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521, USA
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yaroslav Tserkovnyak
- Department of Physics & Astronomy, University of California, Los Angeles, CA, 90095, USA
| | - Jing Shi
- Department of Physics & Astronomy, University of California, Riverside, CA, 92521, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA. .,Department of Physics & Astronomy, University of California, Los Angeles, CA, 90095, USA.
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41
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Wu CN, Tseng CC, Fanchiang YT, Cheng CK, Lin KY, Yeh SL, Yang SR, Wu CT, Liu T, Wu M, Hong M, Kwo J. High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain. Sci Rep 2018; 8:11087. [PMID: 30038363 PMCID: PMC6056423 DOI: 10.1038/s41598-018-29493-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 07/05/2018] [Indexed: 11/13/2022] Open
Abstract
Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.
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Grants
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
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Affiliation(s)
- C N Wu
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Tseng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Y T Fanchiang
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - C K Cheng
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - K Y Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - S L Yeh
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - S R Yang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C T Wu
- National Nano Device Laboratories, Hsinchu, 30013, Taiwan
| | - T Liu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - M Wu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - M Hong
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
| | - J Kwo
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.
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42
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Zhu S, Meng D, Liang G, Shi G, Zhao P, Cheng P, Li Y, Zhai X, Lu Y, Chen L, Wu K. Proximity-induced magnetism and an anomalous Hall effect in Bi 2Se 3/LaCoO 3: a topological insulator/ferromagnetic insulator thin film heterostructure. NANOSCALE 2018; 10:10041-10049. [PMID: 29774918 DOI: 10.1039/c8nr02083c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Inducing magnetism in a topological insulator (TI) by exchange coupling with a ferromagnetic insulator (FMI) will break the time-reversal symmetry of topological surface states, offering possibilities to realize several predicted novel magneto-electric effects. Seeking suitable FMI materials is crucial for the coupling of heterojunctions, and yet is challenging as well and only a few kinds have been explored. In this report, we introduce epitaxial LaCoO3 thin films on a SrTiO3 substrate, which is an insulating ferromagnet with a Curie temperature of TC ∼ 85 K, to be combined with TIs for proximity coupling. Thin films of the prototype topological insulator, Bi2Se3, are successfully grown onto the (001) surface of LaCoO3/SrTiO3, forming a high-quality TI/FMI heterostructure with a sharp interface. The magnetic and transport measurements manifest the emergence of a ferromagnetic phase in Bi2Se3 films, with additional induced moments and a suppressed weak antilocalization effect, while preserving the carrier mobility of the intrinsic Bi2Se3 films at the same time. Moreover, a signal of an anomalous Hall effect is observed and persists up to temperatures above 100 K, paving the way towards spintronic device applications.
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Affiliation(s)
- Shanna Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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43
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Che X, Murata K, Pan L, He QL, Yu G, Shao Q, Yin G, Deng P, Fan Y, Ma B, Liang X, Zhang B, Han X, Bi L, Yang QH, Zhang H, Wang KL. Proximity-Induced Magnetic Order in a Transferred Topological Insulator Thin Film on a Magnetic Insulator. ACS NANO 2018; 12:5042-5050. [PMID: 29733577 DOI: 10.1021/acsnano.8b02647] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Breaking the time reversal symmetry (TRS) in a topological insulator (TI) by introducing a magnetic order gives rise to exotic quantum phenomena. One of the promising routes to inducing a magnetic order in a TI is utilizing magnetic proximity effect between a TI and a strong magnetic insulator (MI). In this article, we demonstrate a TI/MI heterostructure prepared through transferring a molecular beam epitaxy (MBE)-grown Bi2Se3 film onto a yttrium iron garnet (YIG) substrate via wet transfer. The transferred Bi2Se3 exhibits excellent quality over a large scale. Moreover, through wet transfer we are able to engineer the interface and perform a comparative study to probe the proximity coupling between Bi2Se3 and YIG under different interface conditions. A detailed investigation of both the anomalous Hall effect and quantum corrections to the conductivity in magnetotransport measurements reveals an induced magnetic order as well as TRS breaking in the transferred Bi2Se3 film on YIG. In contrast, a thin layer of AlO x at the interface obstructs the proximity coupling and preserves the TRS, indicating the critical role of the interface in mediating magnetic proximity effect.
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Affiliation(s)
- Xiaoyu Che
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Koichi Murata
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Lei Pan
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Qing Lin He
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , China
| | - Qiming Shao
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Gen Yin
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Peng Deng
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Yabin Fan
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Bo Ma
- State Key Laboratory of Electronic Thin Film and Integrated Devices , University of Electronic Science and Technology of China , Chengdu 610054 , China
| | - Xiao Liang
- National Engineering Research Center of Electromagnetic Radiation Control Materials , University of Electronic Science and Technology of China , Chengdu 610054 , China
| | - Bin Zhang
- Beijing Key Lab of Microstructure and Property of Advanced Materials , Beijing University of Technology , Beijing 100124 , China
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Advanced Materials , Beijing University of Technology , Beijing 100124 , China
| | - Lei Bi
- National Engineering Research Center of Electromagnetic Radiation Control Materials , University of Electronic Science and Technology of China , Chengdu 610054 , China
| | - Qing-Hui Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices , University of Electronic Science and Technology of China , Chengdu 610054 , China
| | - Huaiwu Zhang
- State Key Laboratory of Electronic Thin Film and Integrated Devices , University of Electronic Science and Technology of China , Chengdu 610054 , China
| | - Kang L Wang
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
- Department of Materials Science and Engineering , University of California , Los Angeles , California 90095 , United States
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44
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Samarth N. Quantum materials discovery from a synthesis perspective. NATURE MATERIALS 2017; 16:1068-1076. [PMID: 29066828 DOI: 10.1038/nmat5010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 09/15/2017] [Indexed: 06/07/2023]
Abstract
The synthesis of bulk crystals, thin films and nanostructures plays a seminal role in expanding the frontiers of quantum materials. Crystal growers accomplish this by creating materials aimed at harnessing the complex interplay between quantum wavefunctions and various factors such as dimensionality, topology, Coulomb interactions and symmetry. This Review provides a synthesis perspective on how this discovery of quantum materials takes place. After introducing the general paradigms that arise in this context, we provide a few examples to illustrate how thin-film growers in particular exploit quantum confinement, topology, disorder and interfacial heterogeneity to realize new quantum materials.
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Affiliation(s)
- Nitin Samarth
- Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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