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Li Y, Chan YH, Hlevyack JA, Bowers JW, Chou MY, Chiang TC. Topological Quantum Well States in Pb/Sb Thin-Film Heterostructures. ACS NANO 2024; 18:10243-10248. [PMID: 38530641 PMCID: PMC11008363 DOI: 10.1021/acsnano.4c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/12/2024] [Accepted: 03/21/2024] [Indexed: 03/28/2024]
Abstract
Composite topological heterostructures, wherein topologically protected states are electronically tuned due to their proximity to other matter, are key avenues for exploring emergent physical phenomena. Particularly, pairing a topological material with a superconductor such as Pb is a promising means for generating a topological superconducting phase with exotic Majorana quasiparticles, but oft-neglected is the emergence of bulklike spin-polarized states that are quite relevant to applications. Using high-resolution photoemission spectroscopy and first-principles calculations, we report the emergence of bulk-like spin-polarized topological quantum well states with long coherence lengths in Pb films grown on the topological semimetal Sb. The results establish Pb/Sb heterostructures as topological superconductor candidates and advance the current understanding of topological coupling effects required for realizing emergent physics and for designing advanced spintronic device architectures.
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Affiliation(s)
- Yao Li
- Department
of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana−Champaign; Urbana, Illinois 61801, United States
| | - Yang-hao Chan
- Institute
of Atomic and Molecular Sciences, Academia
Sinica, Taipei 10617, Taiwan
- Physics
Division, National Center for Theoretical
Sciences, Taipei 10617, Taiwan
| | - Joseph A. Hlevyack
- Department
of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana−Champaign; Urbana, Illinois 61801, United States
| | - John W. Bowers
- Department
of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana−Champaign; Urbana, Illinois 61801, United States
| | - Mei-Yin Chou
- Institute
of Atomic and Molecular Sciences, Academia
Sinica, Taipei 10617, Taiwan
- Department
of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Tai-Chang Chiang
- Department
of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana−Champaign; Urbana, Illinois 61801, United States
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2
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Liu S, Yu JX, Zhang E, Li Z, Sun Q, Zhang Y, Cao L, Li L, Zhao M, Leng P, Cao X, Li A, Zou J, Kou X, Zang J, Xiu F. Gate-tunable Intrinsic Anomalous Hall Effect in Epitaxial MnBi 2Te 4 Films. NANO LETTERS 2024; 24:16-25. [PMID: 38109350 DOI: 10.1021/acs.nanolett.3c02926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
The anomalous Hall effect (AHE) is an important transport signature revealing topological properties of magnetic materials and their spin textures. Recently, MnBi2Te4 has been demonstrated to be an intrinsic magnetic topological insulator. However, the origin of its intriguing AHE behaviors remains elusive. Here, we demonstrate the Berry curvature-dominated intrinsic AHE in wafer-scale MnBi2Te4 films. By applying back-gate voltages, we observe an ambipolar conduction and n-p transition in ∼7-layer MnBi2Te4, where a quadratic relation between the AHE resistance and longitudinal resistance suggests its intrinsic AHE nature. In particular, for ∼3-layer MnBi2Te4, the AHE sign can be tuned from pristine negative to positive. First-principles calculations unveil that such an AHE reversal originated from the competing Berry curvature between oppositely polarized spin-minority-dominated surface states and spin-majority-dominated inner bands. Our results shed light on the underlying physical mechanism of the intrinsic AHE and provide new perspectives for the unconventional sign-tunable AHE.
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Affiliation(s)
- Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Jie-Xiang Yu
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Qiang Sun
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Yong Zhang
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Liwei Cao
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Lun Li
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Minhao Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Pengliang Leng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Xiangyu Cao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
| | - Ang Li
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiadong Zang
- Department of Physics and Astronomy, University of New Hampshire, Durham, New Hampshire 03824, United States
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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3
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Singh R, Maurya GK, Gautam V, Kumar R, Kumar M, Suresh KG, Panigrahi B, Murapaka C, Haldar A, Kumar P. Proximity induced band gap opening in topological-magnetic heterostructure (Ni 80Fe 20/p-TlBiSe 2/p-Si) under ambient condition. Sci Rep 2023; 13:22290. [PMID: 38097647 PMCID: PMC10721863 DOI: 10.1038/s41598-023-49004-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/02/2023] [Indexed: 12/17/2023] Open
Abstract
The broken time reversal symmetry states may result in the opening of a band gap in TlBiSe2 leading to several interesting phenomena which are potentially relevant for spintronic applications. In this work, the quantum interference and magnetic proximity effects have been studied in Ni80Fe20/p-TlBiSe2/p-Si (Magnetic/TI) heterostructure using physical vapor deposition technique. Raman analysis shows the symmetry breaking with the appearance of A21u mode. The electrical characteristics are investigated under dark and illumination conditions in the absence as well as in the presence of a magnetic field. The outcomes of the examined device reveal excellent photo response in both forward and reverse bias regions. Interestingly, under a magnetic field, the device shows a reduction in electrical conductivity at ambient conditions due to the crossover of weak localization and separation of weak antilocalization, which are experimentally confirmed by magnetoresistance measurement. Further, the photo response has also been assessed by the transient absorption spectroscopy through analysis of charge transfer and carrier relaxation mechanisms. Our results can be beneficial for quantum computation and further study of topological insulator/ferromagnet heterostructure and topological material based spintronic devices due to high spin orbit coupling along with dissipationless conduction channels at the surface states.
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Affiliation(s)
- Roshani Singh
- Spintronics and Magnetic Materials Laboratory, Department of Applied Sciences, Indian Institute of Information Technology Allahabad, Prayagraj, 211015, India
| | - Gyanendra Kumar Maurya
- Spintronics and Magnetic Materials Laboratory, Department of Applied Sciences, Indian Institute of Information Technology Allahabad, Prayagraj, 211015, India
| | - Vidushi Gautam
- Spintronics and Magnetic Materials Laboratory, Department of Applied Sciences, Indian Institute of Information Technology Allahabad, Prayagraj, 211015, India
| | - Rachana Kumar
- CSIR - Indian Institute of Toxicology Research, Lucknow, 226001, India
- CSIR-National Physical Laboratory, New Delhi, India
| | - Mahesh Kumar
- CSIR-National Physical Laboratory, New Delhi, India
| | - K G Suresh
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, 400076, India
| | - Brahmaranjan Panigrahi
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, 502284, Telangana, India
| | - Chandrasekhar Murapaka
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Telangana, 502284, India
| | - Arbinda Haldar
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, 502284, Telangana, India
| | - Pramod Kumar
- Spintronics and Magnetic Materials Laboratory, Department of Applied Sciences, Indian Institute of Information Technology Allahabad, Prayagraj, 211015, India.
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4
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Qiu G, Yang HY, Chong SK, Cheng Y, Tai L, Wang KL. Manipulating Topological Phases in Magnetic Topological Insulators. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2655. [PMID: 37836296 PMCID: PMC10574534 DOI: 10.3390/nano13192655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023]
Abstract
Magnetic topological insulators (MTIs) are a group of materials that feature topological band structures with concurrent magnetism, which can offer new opportunities for technological advancements in various applications, such as spintronics and quantum computing. The combination of topology and magnetism introduces a rich spectrum of topological phases in MTIs, which can be controllably manipulated by tuning material parameters such as doping profiles, interfacial proximity effect, or external conditions such as pressure and electric field. In this paper, we first review the mainstream MTI material platforms where the quantum anomalous Hall effect can be achieved, along with other exotic topological phases in MTIs. We then focus on highlighting recent developments in modulating topological properties in MTI with finite-size limit, pressure, electric field, and magnetic proximity effect. The manipulation of topological phases in MTIs provides an exciting avenue for advancing both fundamental research and practical applications. As this field continues to develop, further investigations into the interplay between topology and magnetism in MTIs will undoubtedly pave the way for innovative breakthroughs in the fundamental understanding of topological physics as well as practical applications.
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Affiliation(s)
- Gang Qiu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Hung-Yu Yang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
| | - Su Kong Chong
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Yang Cheng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
| | - Lixuan Tai
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
| | - Kang L. Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, CA 90095, USA; (H.-Y.Y.); (S.K.C.); (Y.C.); (L.T.)
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5
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Cullen JH, Atencia RB, Culcer D. Spin transfer torques due to the bulk states of topological insulators. NANOSCALE 2023; 15:8437-8446. [PMID: 37096561 DOI: 10.1039/d2nr05176a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Spin torques at topological insulator (TI)/ferromagnet interfaces have received considerable attention in recent years with a view towards achieving full electrical manipulation of magnetic degrees of freedom. The most important question in this field concerns the relative contributions of bulk and surface states to the spin torque, a matter that remains incompletely understood. Whereas the surface state contribution has been extensively studied, the contribution due to the bulk states has received comparatively little attention. Here we study spin torques due to TI bulk states and show that: (i) there is no spin-orbit torque due to the bulk states on a homogeneous magnetisation, in contrast to the surface states, which give rise to a spin-orbit torque via the well-known Edelstein effect. (ii) The bulk states give rise to a spin transfer torque (STT) due to the inhomogeneity of the magnetisation in the vicinity of the interface. This spin transfer torque, which has not been considered in TIs in the past, is somewhat unconventional since it arises from the interplay of the bulk TI spin-orbit coupling and the gradient of the monotonically decaying magnetisation inside the TI. Whereas we consider an idealised model in which the magnetisation gradient is small and the spin transfer torque is correspondingly small, we argue that in real samples the spin transfer torque should be sizable and may provide the dominant contribution due to the bulk states. We show that an experimental smoking gun for identifying the bulk states is the fact that the field-like component of the spin transfer torque generates a spin density with the same size but opposite sign for in-plane and out-of-plane magnetisations. This distinguishes them from the surface states, which are expected to give a spin density of a similar size and the same sign for both an in-plane and out-of-plane magnetisations.
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Affiliation(s)
- James H Cullen
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
| | - Rhonald Burgos Atencia
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
- Facultad de Ingenierías, Departamento de Ciencias Básicas, Universidad del Sinú, Cra.1w No. 38-153, 4536534, Montería, Córdoba 230002, Colombia
| | - Dimitrie Culcer
- School of Physics, The University of New South Wales, Sydney 2052, Australia.
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6
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Shtrikman H, Song MS, Załuska-Kotur MA, Buczko R, Wang X, Kalisky B, Kacman P, Houben L, Beidenkopf H. Intrinsic Magnetic (EuIn)As Nanowire Shells with a Unique Crystal Structure. NANO LETTERS 2022; 22:8925-8931. [PMID: 36343206 PMCID: PMC9706668 DOI: 10.1021/acs.nanolett.2c03012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/27/2022] [Indexed: 06/16/2023]
Abstract
In the pursuit of magneto-electronic systems nonstoichiometric magnetic elements commonly introduce disorder and enhance magnetic scattering. We demonstrate the growth of (EuIn)As shells, with a unique crystal structure comprised of a dense net of Eu inversion planes, over InAs and InAs1-xSbx core nanowires. This is imaged with atomic and elemental resolution which reveal a prismatic configuration of the Eu planes. The results are supported by molecular dynamics simulations. Local magnetic and susceptibility mappings show magnetic response in all nanowires, while a subset bearing a DC signal points to ferromagnetic order. These provide a mechanism for enhancing Zeeman responses, operational at zero applied magnetic field. Such properties suggest that the obtained structures can serve as a preferred platform for time-reversal symmetry broken one-dimensional states including intrinsic topological superconductivity.
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Affiliation(s)
- Hadas Shtrikman
- Department
of Condensed Matter Physics, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | - Man Suk Song
- Department
of Condensed Matter Physics, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | | | - Ryszard Buczko
- Institute
of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, Warsaw PL-02-668, Poland
| | - Xi Wang
- Department
of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Beena Kalisky
- Department
of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Perla Kacman
- Institute
of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, Warsaw PL-02-668, Poland
| | - Lothar Houben
- Department
of Chemical Research Support, Weizmann Institute
of Science, Rehovot 761001, Israel
| | - Haim Beidenkopf
- Department
of Condensed Matter Physics, Weizmann Institute
of Science, Rehovot 7610001, Israel
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7
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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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8
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Lv Q, Fu PH, Zhuang Q, Yu XL, Wu J. Two-dimensional antiferromagnetic nodal-line semimetal and quantum anomalous Hall state in the van der Waals heterostructure germanene/Mn 2S 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:505702. [PMID: 36261049 DOI: 10.1088/1361-648x/ac9bb9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
Materials with interactions between the topology and magnetism are triggering increasing interest. We constructed a two-dimensional (2D) van der Waals heterostructure germanene/Mn2S2, where the germanene is a quantum spin Hall insulator and Mn2S2provides antiferromagnetic (AFM) interactions. In this structure, a 2D AFM nodal-line semimetal (NLSM) phase is expected without the spin-orbit coupling (SOC), which is of a high density of states around the Fermi level. The band touching rings originate from the intersection between different spin components ofporbitals of germanene. This result provides a possible 2D realization of NLSMs, which are usually realized in three-dimensional systems. When the SOC is present, a quantum anomalous Hall (QAH) state emerges with the annihilation of the band-touching rings. The nontrivial topology is determined by calculating the Chern number and Wannier charge centers. This provides an alternative platform to realize QAH states. These results could also provide the possibility of further understanding the topological states in NLSM and electronic applications.
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Affiliation(s)
- Qianqian Lv
- Department of Physics, Harbin Institute of Technology, Harbin 150001, People's Republic of China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Pei-Hao Fu
- Department of Physics, Harbin Institute of Technology, Harbin 150001, People's Republic of China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Quan Zhuang
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College of Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao 028000, People's Republic of China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- International Quantum Academy, Shenzhen 518048, People's Republic of China
| | - Jiansheng Wu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
- International Quantum Academy, Shenzhen 518048, People's Republic of China
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9
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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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10
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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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11
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Xu X, Li Y, Chien CL. Anomalous transverse resistance in the topological superconductor β-Bi 2Pd. Nat Commun 2022; 13:5321. [PMID: 36085297 PMCID: PMC9463149 DOI: 10.1038/s41467-022-32877-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/08/2022] [Indexed: 11/09/2022] Open
Abstract
A supercurrent flowing in a superconductor meets no resistance. Yet an electric field may still be established within the superconductor in the presence of dissipative processes, such as vortex motion. Here we report the observation of a transverse voltage drop in superconducting β-Bi2Pd thin films. Unlike the Hall effect in general or in other superconductors, the sign of the observed transverse voltage does not depend on the external magnetic field. Instead, it is dictated by the broken inversion symmetry on the film interfaces. This anomalous transverse voltage, or transverse resistance, is indicative of a chirality that likely resonates with the topological surface states reported in β-Bi2Pd.
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Affiliation(s)
- Xiaoying Xu
- William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Yufan Li
- William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong.
| | - C L Chien
- William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
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12
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Liu P, Eckberg C, Pan L, Zhang P, Wang KL, Lüpke G. Ultrafast optical control of surface and bulk magnetism in magnetic topological insulator/antiferromagnet heterostructure. Sci Rep 2022; 12:12117. [PMID: 35840647 PMCID: PMC9287552 DOI: 10.1038/s41598-022-16205-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/06/2022] [Indexed: 11/09/2022] Open
Abstract
Optical control of the magnetic properties in topological insulator systems is an important step in applying these materials in ultrafast optoelectronic and spintronic schemes. In this work, we report the experimental observation of photo-induced magnetization dynamics in the magnetically doped topological insulator (MTI)/antiferromagnet (AFM) heterostructure composed of Cr-(Bi,Sb)2Te3/CrSb. Through proximity coupling to the AFM layer, the MTI displays a dramatically enhanced magnetism, with robust perpendicular magnetic anisotropy. When subjected to intense laser irradiation, both surface and bulk magnetism of the MTI are weakened by laser-induced heating of the lattice, however, at the surface, the deleterious heat effect is compensated by the strengthening of Dirac-hole-mediated exchange coupling as demonstrated by an unconventional pump-fluence-dependent exchange-bias effect. Through theoretical analyses, the sizes of exchange coupling energies are estimated in the MTI/AFM bilayer structure. The fundamentally different mechanisms supporting the surface and bulk magnetic order in MTIs allow a novel and distinctive photo-induced transient magnetic state with antiparallel spin configuration, which broadens the understanding of the magnetization dynamics of MTIs under ultrashort and intense optical excitation.
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Affiliation(s)
- Peiwen Liu
- Department of Applied Science, The College of William and Mary, Williamsburg, VA, 23187, USA
| | - Chris Eckberg
- Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA.,Fibertek Inc, Herndon, VA, 20171, USA.,DEVCOM Army Research Laboratory, Adelphi, MD, 20783, USA.,DEVCOM Army Research Laboratory, Playa Vista, CA, 90094, USA
| | - Lei Pan
- Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Peng Zhang
- Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Gunter Lüpke
- Department of Applied Science, The College of William and Mary, Williamsburg, VA, 23187, USA.
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13
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Proximity-Induced Magnetism in a Topological Insulator/Half-Metallic Ferromagnetic Thin Film Heterostructure. COATINGS 2022. [DOI: 10.3390/coatings12060750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Topological insulator (TI) Bi2Se3 thin films were prepared on half-metallic ferromagnetic La0.7Sr0.3MnO3 thin film by magnetron sputtering, forming a TI/FM heterostructure. The conductivity of Bi2Se3was modified by La0.7Sr0.3MnO3 at high- and low-temperature regions via different mechanisms, which could be explained by the short-range interactions and long-range interaction between ferromagnetic insulator and Bi2Se3 due to the proximity effect. Magnetic and transport measurements prove that the ferromagnetic phase and extra magnetic moment are induced in Bi2Se3 films. The weak anti-localized (WAL) effect was suppressed in Bi2Se3 films, accounting for the magnetism of La0.7Sr0.3MnO3 layers. This work clarifies the special behavior in Bi2Se3/La0.7Sr0.3MnO3 heterojunctions, which provides an effective way to study the magnetic proximity effect of the ferromagnetic phase in topological insulators.
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14
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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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15
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Progress and prospects in magnetic topological materials. Nature 2022; 603:41-51. [PMID: 35236973 DOI: 10.1038/s41586-021-04105-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 10/06/2021] [Indexed: 11/09/2022]
Abstract
Magnetic topological materials represent a class of compounds with properties that are strongly influenced by the topology of their electronic wavefunctions coupled with the magnetic spin configuration. Such materials can support chiral electronic channels of perfect conduction, and can be used for an array of applications, from information storage and control to dissipationless spin and charge transport. Here we review the theoretical and experimental progress achieved in the field of magnetic topological materials, beginning with the theoretical prediction of the quantum anomalous Hall effect without Landau levels, and leading to the recent discoveries of magnetic Weyl semimetals and antiferromagnetic topological insulators. We outline recent theoretical progress that has resulted in the tabulation of, for the first time, all magnetic symmetry group representations and topology. We describe several experiments realizing Chern insulators, Weyl and Dirac magnetic semimetals, and an array of axionic and higher-order topological phases of matter, and we survey future perspectives.
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16
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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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17
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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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18
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Li P, You Y, Huang K, Luo W. Quantum anomalous Hall effect in Cr 2Ge 2Te 6/Bi 2Se 3/Cr 2Ge 2Te 6heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465003. [PMID: 34433141 DOI: 10.1088/1361-648x/ac2117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Currently, quantum anomalous Hall (QAH) effect can only be observed at very low temperatures, which severely hinders its utilization from spintronics to quantum computation. Finding or predicting new systems supporting QAH effect at high temperatures remains essential and challenging. This work presents first-principles studies on the proximity effect between Bi2Se3slabs and Cr2Ge2Te6(CGT) layers, reporting that Chern insulators are available in CGT/Bi2Se3/CGT heterostructures. If the sandwiched Bi2Se3slab is 4 quintuple layers (QLs) or thicker, the Chern insulating state is robust against the interfacial stacking manner. If the Bi2Se3slab is only 2 or 3 QLs, the CrBi- and CrH-aligned heterostructures are also Chern insulators, while the CrSe-aligned ones are trivial. The Chern insulators support the Hall conductivityσxy=e2/hand have energy gaps ranging from 3 to 20 meV, implying QAH effect at higher temperatures. An effective model Hamiltonian is introduced to understand the topological phase of the heterostructures.
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Affiliation(s)
- Ping Li
- Key Laboratory of Advanced Electronic Materials and Devices, School of Mathematics and Physics, Anhui Jianzhu University, Hefei, 230601, People's Republic of China
| | - Yuwei You
- Key Laboratory of Advanced Electronic Materials and Devices, School of Mathematics and Physics, Anhui Jianzhu University, Hefei, 230601, People's Republic of China
| | - Kai Huang
- Key Laboratory of Advanced Electronic Materials and Devices, School of Mathematics and Physics, Anhui Jianzhu University, Hefei, 230601, People's Republic of China
| | - Weidong Luo
- Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
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19
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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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20
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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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21
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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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22
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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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23
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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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24
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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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25
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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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26
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Liu S, Yang K, Liu W, Zhang E, Li Z, Zhang X, Liao Z, Zhang W, Sun J, Yang Y, Gao H, Huang C, Ai L, Wong PKJ, Wee ATS, N’Diaye AT, Morton SA, Kou X, Zou J, Xu Y, Wu H, Xiu F. Two-dimensional ferromagnetic superlattices. Natl Sci Rev 2020; 7:745-754. [PMID: 34692093 PMCID: PMC8289050 DOI: 10.1093/nsr/nwz205] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/02/2019] [Accepted: 12/13/2019] [Indexed: 11/14/2022] Open
Abstract
Mechanically exfoliated two-dimensional ferromagnetic materials (2D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature (T C) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their T C, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-T C 2D FM Fe3GeTe2 (FGT) via A-type antiferromagnetic material CrSb (CS) which strongly couples to FGT. A superlattice structure of (FGT/CS)n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism (XMCD) measurements, we have unequivocally discovered that T C of 4-layer Fe3GeTe2 can be significantly enhanced from 140 K to 230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic CrSb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the T C enhancement of the Fe3GeTe2 films, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, T C can be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices.
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Affiliation(s)
- Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ke Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Xiaoqian Zhang
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Zhiming Liao
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
| | - Wen Zhang
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Jiabao Sun
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Yunkun Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Han Gao
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
| | - Ce Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
| | - Alpha T N’Diaye
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Simon A Morton
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Yongbing Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Hua Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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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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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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29
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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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30
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Chen B, Fei F, Zhang D, Zhang B, Liu W, Zhang S, Wang P, Wei B, Zhang Y, Zuo Z, Guo J, Liu Q, Wang Z, Wu X, Zong J, Xie X, Chen W, Sun Z, Wang S, Zhang Y, Zhang M, Wang X, Song F, Zhang H, Shen D, Wang B. Intrinsic magnetic topological insulator phases in the Sb doped MnBi 2Te 4 bulks and thin flakes. Nat Commun 2019; 10:4469. [PMID: 31578337 PMCID: PMC6775157 DOI: 10.1038/s41467-019-12485-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/12/2019] [Indexed: 11/29/2022] Open
Abstract
Magnetic topological insulators (MTIs) offer a combination of topologically nontrivial characteristics and magnetic order and show promise in terms of potentially interesting physical phenomena such as the quantum anomalous Hall (QAH) effect and topological axion insulating states. However, the understanding of their properties and potential applications have been limited due to a lack of suitable candidates for MTIs. Here, we grow two-dimensional single crystals of Mn(SbxBi(1-x))2Te4 bulk and exfoliate them into thin flakes in order to search for intrinsic MTIs. We perform angle-resolved photoemission spectroscopy, low-temperature transport measurements, and first-principles calculations to investigate the band structure, transport properties, and magnetism of this family of materials, as well as the evolution of their topological properties. We find that there exists an optimized MTI zone in the Mn(SbxBi(1-x))2Te4 phase diagram, which could possibly host a high-temperature QAH phase, offering a promising avenue for new device applications.
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Affiliation(s)
- Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China.
| | - Dongqin Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Bo Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Wanling Liu
- Division of Photon Science and Condensed Matter Physics, School of Physical Science and Technology, ShanghaiTech University, 200031, Shanghai, China
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 200050, Shanghai, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Pengdong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Boyuan Wei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Yong Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Zewen Zuo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Jingwen Guo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Qianqian Liu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Zilu Wang
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Xuchuan Wu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Junyu Zong
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Xuedong Xie
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Wang Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Shancai Wang
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Yi Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Minhao Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Xuefeng Wang
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, 210093, Nanjing, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China.
| | - Haijun Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
| | - Dawei Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 200050, Shanghai, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Baigeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
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31
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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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32
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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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33
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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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34
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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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35
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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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36
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Eremeev SV, Otrokov MM, Chulkov EV. New Universal Type of Interface in the Magnetic Insulator/Topological Insulator Heterostructures. NANO LETTERS 2018; 18:6521-6529. [PMID: 30260648 DOI: 10.1021/acs.nanolett.8b03057] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetic proximity effect at the interface between magnetic and topological insulators (MIs and TIs) is considered to have great potential in spintronics as, in principle, it allows realizing the quantum anomalous Hall and topological magneto-electric effects (QAHE and TME). Although an out-of-plane magnetization induced in a TI by the proximity effect was successfully probed in experiments, first-principles calculations reveal that a strong electrostatic potential mismatch at abrupt MI/TI interfaces creates harmful trivial states rendering both the QAHE and TME unfeasible in practice. Here on the basis of recent progress in formation of planar self-assembled single layer MI/TI heterostructure (T. Hirahara et al. Nano Lett. 2017 , 17 , 3493 - 3500 ), we propose a conceptually new type of the MI/TI interfaces by means of density functional theory calculations. By considering MnSe/Bi2Se3, MnTe/Bi2Te3, and EuS/Bi2Se3 we demonstrate that, instead of a sharp MI/TI interface clearly separating the two subsystems, it is energetically far more favorable to form a built-in interface via insertion of the MI film inside the TI's surface quintuple layer (e.g., Se-Bi-Se-[MnSe]-Bi-Se) where it forms a bulk-like MI structure. This results in a smooth MI-to-TI connection that yields the interface electronic structure essentially free of trivial states. Our findings open a new direction in studies of the MI/TI interfaces and restore their potential for the QAHE and TME observation.
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Affiliation(s)
- Sergey V Eremeev
- Institute of Strength Physics and Materials Science , Tomsk 634055 , Russia
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4 , 20018 San Sebastián/Donostia , Basque Country , Spain
| | - Mikhail M Otrokov
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Departamento de Física de Materiales UPV/EHU , Centro de Física de Materiales CFM - MPC and Centro Mixto CSIC-UPV/EHU , 20080 San Sebastián/Donostia , Spain
- IKERBASQUE , Basque Foundation for Science , 48011 Bilbao , Spain
| | - Evgueni V Chulkov
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4 , 20018 San Sebastián/Donostia , Basque Country , Spain
- Departamento de Física de Materiales UPV/EHU , Centro de Física de Materiales CFM - MPC and Centro Mixto CSIC-UPV/EHU , 20080 San Sebastián/Donostia , Spain
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37
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He QL, Yin G, Yu L, Grutter AJ, Pan L, Chen CZ, Che X, Yu G, Zhang B, Shao Q, Stern AL, Casas B, Xia J, Han X, Kirby BJ, Lake RK, Law KT, Wang KL. Topological Transitions Induced by Antiferromagnetism in a Thin-Film Topological Insulator. PHYSICAL REVIEW LETTERS 2018; 121:096802. [PMID: 30230908 DOI: 10.1103/physrevlett.121.096802] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Indexed: 06/08/2023]
Abstract
Magnetism in topological insulators (TIs) opens a topologically nontrivial exchange band gap, providing an exciting platform for manipulating the topological order through an external magnetic field. Here, we show that the surface of an antiferromagnetic thin film can magnetize the top and the bottom TI surface states through interfacial couplings. During the magnetization reversal, intermediate spin configurations are ascribed from unsynchronized magnetic switchings. This unsynchronized switching develops antisymmetric magnetoresistance spikes during magnetization reversals, which might originate from a series of topological transitions. With the high Néel ordering temperature provided by the antiferromagnetic layers, the signature of the induced topological transition persists up to ∼90 K.
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Affiliation(s)
- Qing Lin He
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Gen Yin
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Luyan Yu
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Alexander J Grutter
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - Lei Pan
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Chui-Zhen Chen
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Xiaoyu Che
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Guoqiang Yu
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Bin Zhang
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, 100124, Beijing, China
| | - Qiming Shao
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Alexander L Stern
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Brian Casas
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, 100124, Beijing, China
| | - Brian J Kirby
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - Roger K Lake
- Laboratory for Terascale and Terahertz Electronics (LATTE), Department of Electrical and Computer Engineering, University of California, Riverside, Riverside, California 92521, USA
| | - K T Law
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
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38
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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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39
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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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Zhang C, Lu HZ, Shen SQ, Chen YP, Xiu F. Towards the manipulation of topological states of matter: a perspective from electron transport. Sci Bull (Beijing) 2018; 63:580-594. [PMID: 36658845 DOI: 10.1016/j.scib.2018.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/21/2023]
Abstract
The introduction of topological invariants, ranging from insulators to metals, has provided new insights into the traditional classification of electronic states in condensed matter physics. A sudden change in the topological invariant at the boundary of a topological nontrivial system leads to the formation of exotic surface states that are dramatically different from its bulk. In recent years, significant advancements in the exploration of the physical properties of these topological systems and regarding device research related to spintronics and quantum computation have been made. Here, we review the progress of the characterization and manipulation of topological phases from the electron transport perspective and also the intriguing chiral/Majorana states that stem from them. We then discuss the future directions of research into these topological states and their potential applications.
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Affiliation(s)
- Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Hai-Zhou Lu
- Institute for Quantum Science and Engineering and Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - Shun-Qing Shen
- Department of Physics, The University of Hong Kong, Hong Kong, China
| | - Yong P Chen
- Department of Physics and Astronomy, Purdue University, West Lafayette 47907, USA; Birck Nanotechnology Center, Purdue University, West Lafayette 47907, USA; School of Electrical and Computer Engineering, Purdue University, West Lafayette 47907, USA
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China; Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
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41
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Lai YC, Xu HY, Huang L, Grebogi C. Relativistic quantum chaos-An emergent interdisciplinary field. CHAOS (WOODBURY, N.Y.) 2018; 28:052101. [PMID: 29857689 DOI: 10.1063/1.5026904] [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
Quantum chaos is referred to as the study of quantum manifestations or fingerprints of classical chaos. A vast majority of the studies were for nonrelativistic quantum systems described by the Schrödinger equation. Recent years have witnessed a rapid development of Dirac materials such as graphene and topological insulators, which are described by the Dirac equation in relativistic quantum mechanics. A new field has thus emerged: relativistic quantum chaos. This Tutorial aims to introduce this field to the scientific community. Topics covered include scarring, chaotic scattering and transport, chaos regularized resonant tunneling, superpersistent currents, and energy level statistics-all in the relativistic quantum regime. As Dirac materials have the potential to revolutionize solid-state electronic and spintronic devices, a good understanding of the interplay between chaos and relativistic quantum mechanics may lead to novel design principles and methodologies to enhance device performance.
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Affiliation(s)
- Ying-Cheng Lai
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
| | - Hong-Ya Xu
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
| | - Liang Huang
- School of Physical Science and Technology, and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Celso Grebogi
- Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom
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42
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Fanchiang YT, Chen KHM, Tseng CC, Chen CC, Cheng CK, Yang SR, Wu CN, Lee SF, Hong M, Kwo J. Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi 2Se 3/yttrium iron garnet heterostructures. Nat Commun 2018; 9:223. [PMID: 29335558 PMCID: PMC5768741 DOI: 10.1038/s41467-017-02743-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 12/20/2017] [Indexed: 12/03/2022] Open
Abstract
Harnessing the spin–momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi2Se3/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi2Se3 film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi2Se3/YIG reveals signatures of the magnetic proximity effect of TC as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices. Understanding the effects of topological insulators on magnetization dynamics of adjacent magnetic materials is essential for novel spintronic devices. Here, Fanchiang et al. report thickness dependence of interfacial in-plane magnetic anisotropy and damping enhancement in Bi2Se3/yttrium iron garnet (YIG) bilayers, indicating an important role of topological surface states in the magnetization dynamics of YIG.
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Affiliation(s)
- Y T Fanchiang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - K H M Chen
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Tseng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Chen
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C K Cheng
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - S R Yang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C N Wu
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - S F Lee
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
| | - M Hong
- 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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43
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Wu L, Li C, Chen M, Zhang Y, Han K, Zeng S, Liu X, Ma J, Liu C, Chen J, Zhang J, Venkatesan TV, Pennycook SJ, Coey JMD, Shen L, Ma J, Wang XR, Nan CW. Interface-Induced Enhancement of Ferromagnetism in Insulating LaMnO 3 Ultrathin Films. ACS APPLIED MATERIALS & INTERFACES 2017; 9:44931-44937. [PMID: 29236463 DOI: 10.1021/acsami.7b15364] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Engineering ferromagnetism, by modulating its magnitude or anisotropy, is an important topic in the field of magnetism and spintronics. Among different types of magnetic materials, ferromagnetic insulators, in which magnetic moment unusually coexists with localized electrons, are of particular interest. Here, we report a remarkable interfacial enhancement of the ferromagnetism by adding one unit-cell LaAlO3 adjacent to an insulating LaMnO3 ultrathin film. The enhancement of ferromagnetism is explained in terms of charge transfer at the interface, as evidenced by X-ray absorption spectroscopy and ab initio calculations. This study demonstrates an effective and dramatic approach to modulate the functionality of ferromagnetic insulators, contributing to the arsenal of engineering techniques for future spintronics.
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Affiliation(s)
- Liang Wu
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | | | - Mingfeng Chen
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - Yujun Zhang
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - Kun Han
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Shengwei Zeng
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Xin Liu
- Department of Physics, Beijing Normal University , Beijing 100875, China
| | - Ji Ma
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - Chen Liu
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - Jiahui Chen
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - Jinxing Zhang
- Department of Physics, Beijing Normal University , Beijing 100875, China
| | - T Venky Venkatesan
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | | | - J M D Coey
- School of Physics, Trinity College , Dublin 2, Ireland
- Faculty of Materials Science and Engineering, Beihang University , Beijing 100191, China
| | | | - Jing Ma
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
| | - X Renshaw Wang
- School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University , Singapore 637371, Singapore
| | - Ce-Wen Nan
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University , Beijing 100084, China
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44
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Kim J, Kim KW, Wang H, Sinova J, Wu R. Understanding the Giant Enhancement of Exchange Interaction in Bi_{2}Se_{3}-EuS Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:027201. [PMID: 28753347 DOI: 10.1103/physrevlett.119.027201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 06/07/2023]
Abstract
A recent experiment indicated that a ferromagnetic EuS film in contact with a topological insulator Bi_{2}Se_{3} might show a largely enhanced Curie temperature and perpendicular magnetic anisotropy [F. Katmis et al., Nature (London) 533, 513 (2016).NATUAS0028-083610.1038/nature17635]. Through systematic density functional calculations, we demonstrate that in addition to the factor that Bi_{2}Se_{3} has a strong spin orbit coupling, the topological surface states are crucial to make these unusual behaviors robust as they hybridize with EuS states and extend rather far into the magnetic layers. The magnetic moments of Eu atoms are nevertheless not much enhanced, unlike what was reported in the experiment. Our results and model analyses provide useful insights for how these quantities are linked, and pave a way for the control of properties of magnetic films via contact with topological insulators.
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Affiliation(s)
- Jeongwoo Kim
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Kyoung-Whan Kim
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
| | - Hui Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
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45
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Tang C, Chang CZ, Zhao G, Liu Y, Jiang Z, Liu CX, McCartney MR, Smith DJ, Chen T, Moodera JS, Shi J. Above 400-K robust perpendicular ferromagnetic phase in a topological insulator. SCIENCE ADVANCES 2017; 3:e1700307. [PMID: 28691097 PMCID: PMC5482549 DOI: 10.1126/sciadv.1700307] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 04/21/2017] [Indexed: 05/23/2023]
Abstract
The quantum anomalous Hall effect (QAHE) that emerges under broken time-reversal symmetry in topological insulators (TIs) exhibits many fascinating physical properties for potential applications in nanoelectronics and spintronics. However, in transition metal-doped TIs, the only experimentally demonstrated QAHE system to date, the QAHE is lost at practically relevant temperatures. This constraint is imposed by the relatively low Curie temperature (Tc) and inherent spin disorder associated with the random magnetic dopants. We demonstrate drastically enhanced Tc by exchange coupling TIs to Tm3Fe5O12, a high-Tc magnetic insulator with perpendicular magnetic anisotropy. Signatures showing that the TI surface states acquire robust ferromagnetism are revealed by distinct squared anomalous Hall hysteresis loops at 400 K. Point-contact Andreev reflection spectroscopy confirms that the TI surface is spin-polarized. The greatly enhanced Tc, absence of spin disorder, and perpendicular anisotropy are all essential to the occurrence of the QAHE at high temperatures.
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Affiliation(s)
- Chi Tang
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Cui-Zu Chang
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Gejian Zhao
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - Yawen Liu
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Zilong Jiang
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Chao-Xing Liu
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | | | - David J. Smith
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - Tingyong Chen
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - Jagadeesh S. Moodera
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
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46
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Proximity Effect induced transport Properties between MBE grown (Bi 1-xSb x) 2Se 3 Topological Insulators and Magnetic Insulator CoFe 2O 4. Sci Rep 2017; 7:2422. [PMID: 28546637 PMCID: PMC5445069 DOI: 10.1038/s41598-017-02662-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 04/18/2017] [Indexed: 11/24/2022] Open
Abstract
In this study, we investigate the proximity effect in topological insulator (TI) and magnetic insulator bilayer system. (Bi1−xSbx)2Se3/CoFe2O4 (CFO) heterostructure was fabricated using molecular beam epitaxy and pulsed laser deposition system respectively. As revealed from the magnetoresistance measurement, the weak anti-localization (WAL) is strongly suppressed by proximity effect in (Bi1−xSbx)2Se3/CFO interface. Modified Hikama-Larkin-Nagaoka equation was used to fit the WAL results so that the size of surface state gap can be extracted successfully. The temperature-dependent resistance of the heterostructures at small and large perpendicular magnetic fields were also measured and analyzed. The results indicate that the surface band gap can be induced in TI and continuously enlarged up to 9 T, indicating the gradual alignment of the magnetic moment in CFO under perpendicular magnetic field. The approaches and results accommodated in this work show that CFO can effectively magnetize (Bi1−xSbx)2Se3 and the heterostructures are promising for TI-based spintronic device applications.
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47
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Mohanta N, Kampf AP, Kopp T. Emergent Momentum-Space Skyrmion Texture on the Surface of Topological Insulators. Sci Rep 2017; 7:45664. [PMID: 28378779 PMCID: PMC5381213 DOI: 10.1038/srep45664] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/02/2017] [Indexed: 11/09/2022] Open
Abstract
The quantum anomalous Hall effect has been theoretically predicted and experimentally verified in magnetic topological insulators. In addition, the surface states of these materials exhibit a hedgehoglike “spin” texture in momentum space. Here, we apply the previously formulated low-energy model for Bi2Se3, a parent compound for magnetic topological insulators, to a slab geometry in which an exchange field acts only within one of the surface layers. In this sample set up, the hedgehog transforms into a skyrmion texture beyond a critical exchange field. This critical field marks a transition between two topologically distinct phases. The topological phase transition takes place without energy gap closing at the Fermi level and leaves the transverse Hall conductance unchanged and quantized to e2/2h. The momentum-space skyrmion texture persists in a finite field range. It may find its realization in hybrid heterostructures with an interface between a three-dimensional topological insulator and a ferromagnetic insulator.
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Affiliation(s)
- Narayan Mohanta
- Center for Electronic Correlations and Magnetism, Theoretical Physics III, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
| | - Arno P Kampf
- Center for Electronic Correlations and Magnetism, Theoretical Physics III, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
| | - Thilo Kopp
- Center for Electronic Correlations and Magnetism, Experimental Physics VI, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
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48
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Hellman F, Hoffmann A, Tserkovnyak Y, Beach GSD, Fullerton EE, Leighton C, MacDonald AH, Ralph DC, Arena DA, Dürr HA, Fischer P, Grollier J, Heremans JP, Jungwirth T, Kimel AV, Koopmans B, Krivorotov IN, May SJ, Petford-Long AK, Rondinelli JM, Samarth N, Schuller IK, Slavin AN, Stiles MD, Tchernyshyov O, Thiaville A, Zink BL. Interface-Induced Phenomena in Magnetism. REVIEWS OF MODERN PHYSICS 2017; 89:025006. [PMID: 28890576 PMCID: PMC5587142 DOI: 10.1103/revmodphys.89.025006] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.
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Affiliation(s)
- Frances Hellman
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0401, USA
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712-0264, USA
| | - Daniel C Ralph
- Physics Department, Cornell University, Ithaca, New York 14853, USA; Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620-7100, USA
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Physics Department, University of California, 1156 High Street, Santa Cruz, California 94056, USA
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Avenue Fresnel, 91767 Palaiseau, France
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tomas Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Praha 6, Czech Republic; School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexey V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, The Netherlands
| | - Bert Koopmans
- Department of Applied Physics, Center for NanoMaterials, COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Steven J May
- Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, California 92093, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Mark D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - André Thiaville
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405 Orsay, France
| | - Barry L Zink
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA
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49
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Kubota Y, Murata K, Miyawaki J, Ozawa K, Onbasli MC, Shirasawa T, Feng B, Yamamoto S, Liu RY, Yamamoto S, Mahatha SK, Sheverdyaeva P, Moras P, Ross CA, Suga S, Harada Y, Wang KL, Matsuda I. Interface electronic structure at the topological insulator-ferrimagnetic insulator junction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:055002. [PMID: 27911879 DOI: 10.1088/1361-648x/29/5/055002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An interface electron state at the junction between a three-dimensional topological insulator film, Bi2Se3, and a ferrimagnetic insulator film, Y3Fe5O12 (YIG), was investigated by measurements of angle-resolved photoelectron spectroscopy and x-ray absorption magnetic circular dichroism. The surface state of the Bi2Se3 film was directly observed and localized 3d spin states of the Fe3+ in the YIG film were confirmed. The proximity effect is likely described in terms of the exchange interaction between the localized Fe 3d electrons in the YIG film and delocalized electrons of the surface and bulk states in the Bi2Se3 film.
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Affiliation(s)
- Y Kubota
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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50
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Dong L, Kumar H, Anasori B, Gogotsi Y, Shenoy VB. Rational Design of Two-Dimensional Metallic and Semiconducting Spintronic Materials Based on Ordered Double-Transition-Metal MXenes. J Phys Chem Lett 2017; 8:422-428. [PMID: 28036178 DOI: 10.1021/acs.jpclett.6b02751] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two-dimensional (2D) materials that display robust ferromagnetism have been pursued intensively for nanoscale spintronic applications, but suitable candidates have not been identified. Here we present theoretical predictions on the design of ordered double-transition-metal MXene structures to achieve such a goal. On the basis of the analysis of electron filling in transition-metal cations and first-principles simulations, we demonstrate robust ferromagnetism in Ti2MnC2Tx monolayers regardless of the surface terminations (T = O, OH, and F), as well as in Hf2MnC2O2 and Hf2VC2O2 monolayers. The high magnetic moments (3-4 μB/unit cell) and high Curie temperatures (495-1133 K) of these MXenes are superior to those of existing 2D ferromagnetic materials. Furthermore, semimetal-to-semiconductor and ferromagnetic-to-antiferromagnetic phase transitions are predicted to occur in these materials in the presence of small or moderate tensile in-plane strains (0-3%), which can be externally applied mechanically or internally induced by the choice of transition metals.
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Affiliation(s)
- Liang Dong
- Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Hemant Kumar
- Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Babak Anasori
- Department of Materials Science & Engineering and A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Yury Gogotsi
- Department of Materials Science & Engineering and A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Vivek B Shenoy
- Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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