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Yang J, Wang X, Li S, Wang X, Pan M, Ai M, Yuan H, Peng X, Wang R, Li Q, Zheng F, Zhang P. Robust Two-Dimensional Ferromagnetism in Cr 5Te 8/CrTe 2 Heterostructure with Curie Temperature above 400 K. ACS NANO 2023; 17:23160-23168. [PMID: 37926969 DOI: 10.1021/acsnano.3c09654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
The discovery of ferromagnetism in two-dimensional (2D) van der Waals crystals has generated widespread interest. The seeking of robust 2D ferromagnets with high Curie temperature (Tc) is vitally important for next-generation spintronic devices. However, owing to the enhanced spin fluctuation and weak exchange interaction upon the reduced dimensionalities, the exploring of robust 2D ferromagnets with Tc > 300 K is highly demanded but remains challenging. In this work, we fabricated air-stable 2D Cr5Te8/CrTe2 vertical heterojunctions with Tc above 400 K by the chemical vapor deposition method. Transmission electron microscopy demonstrates a high-quality-crystalline epitaxial structure between tri-Cr5Te8 and 1T-CrTe2 with striped moiré patterns and a superior ambient stability over six months. A built-in dual-axis strain together with strong interfacial coupling cooperatively leads to a record-high Tc for the CrxTey family. A temperature-dependent spin-flip process induces the easy axis of magnetization to rotate from the out-of-plane to the in-plane direction, indicating a phase-dependent proximity coupling effect, rationally interpreted by first-principles calculations of the magnetic anisotropy of a tri-Cr5Te8 and 1T-CrTe2 monolayer. Our results provide a material realization of effectively enhancing the transition temperature of 2D ferromagnetism and manipulating the spin-flip of the easy axis, which will facilitate future spintronic applications.
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Affiliation(s)
- Jielin Yang
- School of Physics, Hubei University, Wuhan 430062, China
| | - Xinyu Wang
- School of Physics, Hubei University, Wuhan 430062, China
| | - Shujing Li
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xina Wang
- School of Physics, Hubei University, Wuhan 430062, China
| | - Minghu Pan
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Mingzhong Ai
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Hui Yuan
- School of Physics, Hubei University, Wuhan 430062, China
| | - Xiaoniu Peng
- School of Physics, Hubei University, Wuhan 430062, China
| | - Ruilong Wang
- School of Physics, Hubei University, Wuhan 430062, China
| | - Quan Li
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Fawei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China
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2
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Zhuo D, Yan ZJ, Sun ZT, Zhou LJ, Zhao YF, Zhang R, Mei R, Yi H, Wang K, Chan MHW, Liu CX, Law KT, Chang CZ. Axion insulator state in hundred-nanometer-thick magnetic topological insulator sandwich heterostructures. Nat Commun 2023; 14:7596. [PMID: 37989754 PMCID: PMC10663498 DOI: 10.1038/s41467-023-43474-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 11/10/2023] [Indexed: 11/23/2023] Open
Abstract
An axion insulator is a three-dimensional (3D) topological insulator (TI), in which the bulk maintains the time-reversal symmetry or inversion symmetry but the surface states are gapped by surface magnetization. The axion insulator state has been observed in molecular beam epitaxy (MBE)-grown magnetically doped TI sandwiches and exfoliated intrinsic magnetic TI MnBi2Te4 flakes with an even number layer. All these samples have a thickness of ~ 10 nm, near the 2D-to-3D boundary. The coupling between the top and bottom surface states in thin samples may hinder the observation of quantized topological magnetoelectric response. Here, we employ MBE to synthesize magnetic TI sandwich heterostructures and find that the axion insulator state persists in a 3D sample with a thickness of ~ 106 nm. Our transport results show that the axion insulator state starts to emerge when the thickness of the middle undoped TI layer is greater than ~ 3 nm. The 3D hundred-nanometer-thick axion insulator provides a promising platform for the exploration of the topological magnetoelectric effect and other emergent magnetic topological states, such as the high-order TI phase.
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Affiliation(s)
- Deyi Zhuo
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Zi-Jie Yan
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Zi-Ting Sun
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, 999077, Hong Kong, China
| | - Ling-Jie Zhou
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ruoxi Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ruobing Mei
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hemian Yi
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - K T Law
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, 999077, Hong Kong, China.
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
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3
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Creation of chiral interface channels for quantized transport in magnetic topological insulator multilayer heterostructures. Nat Commun 2023; 14:770. [PMID: 36765068 PMCID: PMC9918724 DOI: 10.1038/s41467-023-36488-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
One-dimensional chiral interface channels can be created at the boundary of two quantum anomalous Hall (QAH) insulators with different Chern numbers. Such a QAH junction may function as a chiral edge current distributer at zero magnetic field, but its realization remains challenging. Here, by employing an in-situ mechanical mask, we use molecular beam epitaxy to synthesize QAH insulator junctions, in which two QAH insulators with different Chern numbers are connected along a one-dimensional junction. For the junction between Chern numbers of 1 and -1, we observe quantized transport and demonstrate the appearance of the two parallel propagating chiral interface channels along the magnetic domain wall at zero magnetic field. For the junction between Chern numbers of 1 and 2, our quantized transport shows that a single chiral interface channel appears at the interface. Our work lays the foundation for the development of QAH insulator-based electronic and spintronic devices and topological chiral networks.
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4
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Ying Z, Chen B, Li C, Wei B, Dai Z, Guo F, Pan D, Zhang H, Wu D, Wang X, Zhang S, Fei F, Song F. Large Exchange Bias Effect and Coverage-Dependent Interfacial Coupling in CrI 3/MnBi 2Te 4 van der Waals Heterostructures. NANO LETTERS 2023; 23:765-771. [PMID: 36542799 DOI: 10.1021/acs.nanolett.2c02882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Igniting interface magnetic ordering of magnetic topological insulators by building a van der Waals heterostructure can help to reveal novel quantum states and design functional devices. Here, we observe an interesting exchange bias effect, indicating successful interfacial magnetic coupling, in CrI3/MnBi2Te4 ferromagnetic insulator/antiferromagnetic topological insulator (FMI/AFM-TI) heterostructure devices. The devices originally exhibit a negative exchange bias field, which decays with increasing temperature and is unaffected by the back-gate voltage. When we change the device configuration to be half-covered by CrI3, the exchange bias becomes positive with a very large exchange bias field exceeding 300 mT. Such sensitive manipulation is explained by the competition between the FM and AFM coupling at the interface of CrI3 and MnBi2Te4, pointing to coverage-dependent interfacial magnetic interactions. Our work will facilitate the development of topological and antiferromagnetic devices.
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Affiliation(s)
- Zhe Ying
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Chunfeng Li
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Boyuan Wei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Zheng Dai
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Fengyi Guo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Danfeng Pan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
- Microfabrication and Integration Technology Center, Nanjing University, Nanjing 210093, China
| | - Haijun Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Di Wu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
| | - Xuefeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
- Atom Manufacturing Institute, Nanjing 211806, China
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5
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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: 1] [Impact Index Per Article: 0.5] [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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6
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He QL, Hughes TL, Armitage NP, Tokura Y, Wang KL. Topological spintronics and magnetoelectronics. NATURE MATERIALS 2022; 21:15-23. [PMID: 34949869 DOI: 10.1038/s41563-021-01138-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 09/21/2021] [Indexed: 05/08/2023]
Abstract
Topological electronic materials, such as topological insulators, are distinct from trivial materials in the topology of their electronic band structures that lead to robust, unconventional topological states, which could bring revolutionary developments in electronics. This Perspective summarizes developments of topological insulators in various electronic applications including spintronics and magnetoelectronics. We group and analyse several important phenomena in spintronics using topological insulators, including spin-orbit torque, the magnetic proximity effect, interplay between antiferromagnetism and topology, and the formation of topological spin textures. We also outline recent developments in magnetoelectronics such as the axion insulator and the topological magnetoelectric effect observed using different topological insulators.
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Affiliation(s)
- Qing Lin He
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
- Collaborative Innovation Center of Quantum Matter, Beijing, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, China.
| | - Taylor L Hughes
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - N Peter Armitage
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Tokyo College, University of Tokyo, Tokyo, Japan
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, USA.
- Center of Quantum Sciences and Engineering, University of California, Los Angeles, CA, USA.
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7
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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: 9] [Impact Index Per Article: 3.0] [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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8
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Chen JR, Tse PL, Krivorotov IN, Lu JG. Spin-momentum locking induced non-local voltage in topological insulator nanowire. NANOSCALE 2020; 12:22958-22962. [PMID: 33206099 DOI: 10.1039/d0nr06590k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The momentum and spin of charge carriers in the topological insulators are constrained to be perpendicular to each other due to the strong spin-orbit coupling. We have investigated this unique spin-momentum locking property in Sb2Te3 topological insulator nanowires by injecting spin-polarized electrons through magnetic tunnel junction electrodes. Non-local voltage measurements exhibit an asymmetry with respect to the magnetic field applied perpendicular to the nanowire channel, which is remarkably different from that of a non-local measurement in a channel that lacks spin-momentum locking. In stark contrast to conventional non-local spin valves, simultaneous reversal of magnetic moments of all magnetic contacts to the Sb2Te3 nanowire alters the non-local voltage. This unusual asymmetry is a clear signature of the spin-momentum locking in the Sb2Te3 nanowire surface states.
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Affiliation(s)
- Jen-Ru Chen
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
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9
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Pan L, Grutter A, Zhang P, Che X, Nozaki T, Stern A, Street M, Zhang B, Casas B, He QL, Choi ES, Disseler SM, Gilbert DA, Yin G, Shao Q, Deng P, Wu Y, Liu X, Kou X, Masashi S, Han X, Binek C, Chambers S, Xia J, Wang KL. Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2001460. [PMID: 32691882 DOI: 10.1002/adma.202001460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Integration of a quantum anomalous Hall insulator with a magnetically ordered material provides an additional degree of freedom through which the resulting exotic quantum states can be controlled. Here, an experimental observation is reported of the quantum anomalous Hall effect in a magnetically-doped topological insulator grown on the antiferromagnetic insulator Cr2 O3 . The exchange coupling between the two materials is investigated using field-cooling-dependent magnetometry and polarized neutron reflectometry. Both techniques reveal strong interfacial interaction between the antiferromagnetic order of the Cr2 O3 and the magnetic topological insulator, manifested as an exchange bias when the sample is field-cooled under an out-of-plane magnetic field, and an exchange spring-like magnetic depth profile when the system is magnetized within the film plane. These results identify antiferromagnetic insulators as suitable candidates for the manipulation of magnetic and topological order in topological insulator films.
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Affiliation(s)
- Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Alexander Grutter
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Xiaoyu Che
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Tomohiro Nozaki
- Department of Electronic Engineering, Tohoku University, Sendai, 980-8579, Japan
| | - Alex Stern
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Mike Street
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588, USA
| | - Bing Zhang
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Brian Casas
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, 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
| | - Eun Sang Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310-3706, USA
| | - Steven M Disseler
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Dustin A Gilbert
- Department of Materials Science, University of Tennessee, Knoxville, TN, 37996, USA
| | - Gen Yin
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Qiming Shao
- Department of Electrical and Computer Engineering, University of California, 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 Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Yingying Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Xiaoyang Liu
- School of Information Science and Technology, ShanghaiTech University, Shanghai, 200031, China
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai, 200031, China
| | - Sahashi Masashi
- Department of Electronic Engineering, Tohoku University, Sendai, 980-8579, Japan
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Christian Binek
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588, USA
| | - Scott Chambers
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, 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, University of California, Los Angeles, CA, 90095, USA
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10
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Liu J, Singh A, Liu YYF, Ionescu A, Kuerbanjiang B, Barnes CHW, Hesjedal T. Exchange Bias in Magnetic Topological Insulator Superlattices. NANO LETTERS 2020; 20:5315-5322. [PMID: 32551677 PMCID: PMC7467763 DOI: 10.1021/acs.nanolett.0c01666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/17/2020] [Indexed: 06/11/2023]
Abstract
Magnetic doping and proximity coupling can open a band gap in a topological insulator (TI) and give rise to dissipationless quantum conduction phenomena. Here, by combining these two approaches, we demonstrate a novel TI superlattice structure that is alternately doped with transition and rare earth elements. An unexpected exchange bias effect is unambiguously confirmed in the superlattice with a large exchange bias field using magneto-transport and magneto-optical techniques. Further, the Curie temperature of the Cr-doped layers in the superlattice is found to increase by 60 K compared to a Cr-doped single-layer film. This result is supported by density-functional-theory calculations, which indicate the presence of antiferromagnetic ordering in Dy:Bi2Te3 induced by proximity coupling to Cr:Sb2Te3 at the interface. This work provides a new pathway to realizing the quantum anomalous Hall effect at elevated temperatures and axion insulator state at zero magnetic field by interface engineering in TI heterostructures.
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Affiliation(s)
- Jieyi Liu
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Parks Road, Oxford OX1
3PU, United Kingdom
- Cavendish
Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Angadjit Singh
- Cavendish
Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Department
of Physics, Royal Holloway, University of
London, Egham Hill, Egham TW20 0EX, United Kingdom
| | - Yu Yang Fredrik Liu
- Cavendish
Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Adrian Ionescu
- Cavendish
Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Balati Kuerbanjiang
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Parks Road, Oxford OX1
3PU, United Kingdom
| | - Crispin H. W. Barnes
- Cavendish
Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Thorsten Hesjedal
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Parks Road, Oxford OX1
3PU, United Kingdom
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11
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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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