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Han X, Yi HT, Oh S, Wu L. Magneto-optical Effects of an Artificially Layered Ferromagnetic Topological Insulator with a TC of 160 K. NANO LETTERS 2024; 24:914-919. [PMID: 38190329 DOI: 10.1021/acs.nanolett.3c04103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Magnetic topological insulators are a fertile platform for studying the interplay between magnetism and topology. The unique electronic band structure can induce exotic transport and optical properties. However, a comprehensive optical study at both near-infrared and terahertz frequencies has been lacking. Here, we report magneto-optical effects from a heterostructure of a Cr-incorporated topological insulator, CBST. By measuring the magneto-optical Kerr effect, we observe a high temperature ferromagnetic transition (160 K) in the CBST film. We also use time-domain terahertz polarimetry to reveal a terahertz Faraday rotation of 1.5 mrad and a terahertz Kerr rotation of 3.6 mrad at 2 K. The calculated terahertz Hall conductance is 0.42 e2/h. Our work shows the optical responses of an artificially layered magnetic topological insulator, paving the way toward a high-temperature quantum anomalous Hall effect via heterostructure engineering.
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Affiliation(s)
- Xingyue Han
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Hee Taek Yi
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Seongshik Oh
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Liang Wu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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2
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Zhao YF, Zhang R, Sun ZT, Zhou LJ, Zhuo D, Yan ZJ, Yi H, Wang K, Chan MHW, Liu CX, Law KT, Chang CZ. 3D Quantum Anomalous Hall Effect in Magnetic Topological Insulator Trilayers of Hundred-Nanometer Thickness. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2310249. [PMID: 38118065 DOI: 10.1002/adma.202310249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/07/2023] [Indexed: 12/22/2023]
Abstract
Magnetic topological states refer to a class of exotic phases in magnetic materials with the non-trivial topological property determined by magnetic spin configurations. An example of such states is the quantum anomalous Hall (QAH) state, which is a zero magnetic field manifestation of the quantum Hall effect. Current research in this direction focuses on QAH insulators with a thickness of less than 10 nm. Here, molecular beam epitaxy (MBE) is employed to synthesize magnetic TI trilayers with a thickness of up to ≈106 nm. It is found that these samples exhibit well-quantized Hall resistance and vanishing longitudinal resistance at zero magnetic field. By varying the magnetic dopants, gate voltages, temperature, and external magnetic fields, the properties of these thick QAH insulators are examined and the robustness of the 3D QAH effect is demonstrated. The realization of the well-quantized 3D QAH effect indicates that the nonchiral side surface states of the thick magnetic TI trilayers are gapped and thus do not affect the QAH quantization. The 3D QAH insulators of hundred-nanometer thickness provide a promising platform for the exploration of fundamental physics, including axion physics and image magnetic monopole, and the advancement of electronic and spintronic devices to circumvent Moore's law.
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Affiliation(s)
- Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ruoxi Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Zi-Ting Sun
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, China
| | - Ling-Jie Zhou
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Deyi Zhuo
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Zi-Jie Yan
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hemian Yi
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - K T Law
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, China
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
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3
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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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4
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Jin KH, Jiang W, Sethi G, Liu F. Topological quantum devices: a review. NANOSCALE 2023; 15:12787-12817. [PMID: 37490310 DOI: 10.1039/d3nr01288c] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
The introduction of the concept of topology into condensed matter physics has greatly deepened our fundamental understanding of transport properties of electrons as well as all other forms of quasi particles in solid materials. It has also fostered a paradigm shift from conventional electronic/optoelectronic devices to novel quantum devices based on topology-enabled quantum device functionalities that transfer energy and information with unprecedented precision, robustness, and efficiency. In this article, the recent research progress in topological quantum devices is reviewed. We first outline the topological spintronic devices underlined by the spin-momentum locking property of topology. We then highlight the topological electronic devices based on quantized electron and dissipationless spin conductivity protected by topology. Finally, we discuss quantum optoelectronic devices with topology-redefined photoexcitation and emission. The field of topological quantum devices is only in its infancy, we envision many significant advances in the near future.
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Affiliation(s)
- Kyung-Hwan Jin
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Wei Jiang
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Gurjyot Sethi
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
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5
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Tcakaev A, Rubrecht B, Facio JI, Zabolotnyy VB, Corredor LT, Folkers LC, Kochetkova E, Peixoto TRF, Kagerer P, Heinze S, Bentmann H, Green RJ, Gargiani P, Valvidares M, Weschke E, Haverkort MW, Reinert F, van den Brink J, Büchner B, Wolter AUB, Isaeva A, Hinkov V. Intermixing-Driven Surface and Bulk Ferromagnetism in the Quantum Anomalous Hall Candidate MnBi 6 Te 10. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2203239. [PMID: 36802132 PMCID: PMC10074120 DOI: 10.1002/advs.202203239] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/17/2023] [Indexed: 06/18/2023]
Abstract
The recent realizations of the quantum anomalous Hall effect (QAHE) in MnBi2 Te4 and MnBi4 Te7 benchmark the (MnBi2 Te4 )(Bi2 Te3 )n family as a promising hotbed for further QAHE improvements. The family owes its potential to its ferromagnetically (FM) ordered MnBi2 Te4 septuple layers (SLs). However, the QAHE realization is complicated in MnBi2 Te4 and MnBi4 Te7 due to the substantial antiferromagnetic (AFM) coupling between the SLs. An FM state, advantageous for the QAHE, can be stabilized by interlacing the SLs with an increasing number n of Bi2 Te3 quintuple layers (QLs). However, the mechanisms driving the FM state and the number of necessary QLs are not understood, and the surface magnetism remains obscure. Here, robust FM properties in MnBi6 Te10 (n = 2) with Tc ≈ 12 K are demonstrated and their origin is established in the Mn/Bi intermixing phenomenon by a combined experimental and theoretical study. The measurements reveal a magnetically intact surface with a large magnetic moment, and with FM properties similar to the bulk. This investigation thus consolidates the MnBi6 Te10 system as perspective for the QAHE at elevated temperatures.
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Affiliation(s)
- Abdul‐Vakhab Tcakaev
- Physikalisches Institut (EP‐IV)Universität WürzburgAm HublandD‐97074WürzburgGermany
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
| | - Bastian Rubrecht
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
| | - Jorge I. Facio
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
- Centro Atómico BarilocheInstituto de Nanociencia y Nanotecnología (CNEA‐CONICET) and Instituto Balseiro. Av. Bustillo 9500Bariloche8400Argentina
| | - Volodymyr B. Zabolotnyy
- Physikalisches Institut (EP‐IV)Universität WürzburgAm HublandD‐97074WürzburgGermany
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
| | - Laura T. Corredor
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
| | - Laura C. Folkers
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Institut für Festkörper‐ und MaterialphysikTechnische Universität DresdenD‐01062DresdenGermany
| | - Ekaterina Kochetkova
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
| | - Thiago R. F. Peixoto
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Physikalisches Institut (EP‐VII)Universität WürzburgAm HublandD‐97074WürzburgGermany
| | - Philipp Kagerer
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Physikalisches Institut (EP‐VII)Universität WürzburgAm HublandD‐97074WürzburgGermany
| | - Simon Heinze
- Institute for Theoretical PhysicsHeidelberg UniversityPhilosophenweg 1969120HeidelbergGermany
| | - Hendrik Bentmann
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Physikalisches Institut (EP‐VII)Universität WürzburgAm HublandD‐97074WürzburgGermany
| | - Robert J. Green
- Department of Physics and Astronomy and Stewart Blusson Quantum Matter InstituteUniversity of British ColumbiaVancouverBritish ColumbiaV6T 1Z4Canada
- Department of Physics and Engineering PhysicsUniversity of SaskatchewanSaskatoonSKS7N 5E2Canada
| | - Pierluigi Gargiani
- ALBA Synchrotron Light SourceE‐08290 Cerdanyola del VallèsBarcelonaSpain
| | - Manuel Valvidares
- ALBA Synchrotron Light SourceE‐08290 Cerdanyola del VallèsBarcelonaSpain
| | - Eugen Weschke
- Helmholtz‐Zentrum Berlin für Materialien und EnergieAlbert‐Einstein‐Straße 15D‐12489BerlinGermany
| | - Maurits W. Haverkort
- Institute for Theoretical PhysicsHeidelberg UniversityPhilosophenweg 1969120HeidelbergGermany
| | - Friedrich Reinert
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Physikalisches Institut (EP‐VII)Universität WürzburgAm HublandD‐97074WürzburgGermany
| | - Jeroen van den Brink
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
- Institut für Theoretische PhysikTechnische Universität DresdenD‐01062DresdenGermany
| | - Bernd Büchner
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
- Institut für Festkörper‐ und MaterialphysikTechnische Universität DresdenD‐01062DresdenGermany
| | - Anja U. B. Wolter
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
| | - Anna Isaeva
- Leibniz Institut für Festkörper‐ und Werkstoffforschung (IFW) DresdenHelmholtzstraße 20D‐01069DresdenGermany
- Van der Waals‐Zeeman InstituteDepartment of Physics and AstronomyUniversity of AmsterdamScience Park 904Amsterdam1098 XHThe Netherlands
| | - Vladimir Hinkov
- Physikalisches Institut (EP‐IV)Universität WürzburgAm HublandD‐97074WürzburgGermany
- Würzburg‐Dresden Cluster of Excellence ct.qmatGermany
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6
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Zhou LJ, Mei R, Zhao YF, Zhang R, Zhuo D, Yan ZJ, Yuan W, Kayyalha M, Chan MHW, Liu CX, Chang CZ. Confinement-Induced Chiral Edge Channel Interaction in Quantum Anomalous Hall Insulators. PHYSICAL REVIEW LETTERS 2023; 130:086201. [PMID: 36898119 DOI: 10.1103/physrevlett.130.086201] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
In quantum anomalous Hall (QAH) insulators, the interior is insulating but electrons can travel with zero resistance along one-dimensional (1D) conducting paths known as chiral edge channels (CECs). These CECs have been predicted to be confined to the 1D edges and exponentially decay in the two-dimensional (2D) bulk. In this Letter, we present the results of a systematic study of QAH devices fashioned in a Hall bar geometry of different widths under gate voltages. At the charge neutral point, the QAH effect persists in a Hall bar device with a width of only ∼72 nm, implying the intrinsic decaying length of CECs is less than ∼36 nm. In the electron-doped regime, we find that the Hall resistance deviates quickly from the quantized value when the sample width is less than 1 μm. Our theoretical calculations suggest that the wave function of CEC first decays exponentially and then shows a long tail due to disorder-induced bulk states. Therefore, the deviation from the quantized Hall resistance in narrow QAH samples originates from the interaction between two opposite CECs mediated by disorder-induced bulk states in QAH insulators, consistent with our experimental observations.
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Affiliation(s)
- Ling-Jie Zhou
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ruobing Mei
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yi-Fan Zhao
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ruoxi Zhang
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Deyi Zhuo
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Zi-Jie Yan
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Wei Yuan
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Morteza Kayyalha
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Moses H W Chan
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Chao-Xing Liu
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Cui-Zu Chang
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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7
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Tay H, Zhao YF, Zhou LJ, Zhang R, Yan ZJ, Zhuo D, Chan MHW, Chang CZ. Environmental Doping-Induced Degradation of the Quantum Anomalous Hall Insulators. NANO LETTERS 2023; 23:1093-1099. [PMID: 36715442 DOI: 10.1021/acs.nanolett.2c04871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The quantum anomalous Hall (QAH) insulator carries dissipation-free chiral edge current and thus provides a unique opportunity to develop energy-efficient transformative information technology. Despite promising advances, the QAH insulator has thus far eluded any practical applications. In addition to its low working temperature, the QAH state in magnetically doped topological insulators usually deteriorates with time in ambient conditions. In this work, we store three QAH devices with similar initial properties in different environments. The QAH device without a protection layer in air shows clear degradation and becomes hole-doped. The QAH device kept in an argon glovebox without a protection layer shows no measurable degradation after 560 h, and the device protected by a 3 nm AlOx protection layer in air shows minimal degradation with stable QAH properties. Our work shows a route to preserve the dissipation-free chiral edge state in QAH devices for potential applications in quantum information technology.
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Affiliation(s)
- Han Tay
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ling-Jie Zhou
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ruoxi Zhang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Zi-Jie Yan
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Deyi Zhuo
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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8
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Brahlek M. Criteria for Realizing Room-Temperature Electrical Transport Applications of Topological Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2005698. [PMID: 33145882 DOI: 10.1002/adma.202005698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/25/2020] [Indexed: 06/11/2023]
Abstract
The unusual electronic states found in topological materials can enable a new generation of devices and technologies, yet a long-standing challenge has been finding materials without deleterious parallel bulk conduction. This can arise either from defects or thermally activated carriers. Here, the criteria that materials need to meet to realize transport properties dominated by the topological states, a necessity for a topological device, are clarified. This is demonstrated for 3D topological insulators, 3D Dirac materials, and 1D quantum anomalous Hall insulators, though this can be applied to similar systems. The key parameters are electronic bandgap, dielectric constant, and carrier effective mass, which dictate under what circumstances (defect density, temperature, etc.) the unwanted bulk state will conduct in parallel to the topological states. As these are fundamentally determined by the basic atomic properties, simple chemical arguments can be used to navigate the phase space to ultimately find improved materials. This will enable rapid identification of new systems with improved properties, which is crucial to designing new material systems and push a new generation of topological technologies.
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Affiliation(s)
- Matthew Brahlek
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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9
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Jiang J, Xiao D, Wang F, Shin JH, Andreoli D, Zhang J, Xiao R, Zhao YF, Kayyalha M, Zhang L, Wang K, Zang J, Liu C, Samarth N, Chan MHW, Chang CZ. Concurrence of quantum anomalous Hall and topological Hall effects in magnetic topological insulator sandwich heterostructures. NATURE MATERIALS 2020; 19:732-737. [PMID: 32015537 DOI: 10.1038/s41563-020-0605-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 01/03/2020] [Indexed: 05/08/2023]
Abstract
The quantum anomalous Hall (QAH) effect is a consequence of non-zero Berry curvature in momentum space. The QAH insulator harbours dissipation-free chiral edge states in the absence of an external magnetic field. However, the topological Hall (TH) effect, a hallmark of chiral spin textures, is a consequence of real-space Berry curvature. Here, by inserting a topological insulator (TI) layer between two magnetic TI layers, we realized the concurrence of the TH effect and the QAH effect through electric-field gating. The TH effect is probed by bulk carriers, whereas the QAH effect is characterized by chiral edge states. The appearance of the TH effect in the QAH insulating regime is a consequence of chiral magnetic domain walls that result from the gate-induced Dzyaloshinskii-Moriya interaction and occurs during the magnetization reversal process in the magnetic TI sandwich samples. The coexistence of chiral edge states and chiral spin textures provides a platform for proof-of-concept dissipationless spin-textured spintronic applications.
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Affiliation(s)
- Jue Jiang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Di Xiao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Fei Wang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Jae-Ho Shin
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | | | - Jianxiao Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Run Xiao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Yi-Fan Zhao
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Morteza Kayyalha
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Ling Zhang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Ke Wang
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Jiadong Zang
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Chaoxing Liu
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
| | - Moses H W Chan
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
| | - Cui-Zu Chang
- Department of Physics, The Pennsylvania State University, University Park, PA, USA.
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10
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Pan L, Liu X, He QL, Stern A, Yin G, Che X, Shao Q, Zhang P, Deng P, Yang CY, Casas B, Choi ES, Xia J, Kou X, Wang KL. Probing the low-temperature limit of the quantum anomalous Hall effect. SCIENCE ADVANCES 2020; 6:eaaz3595. [PMID: 32596443 PMCID: PMC7299611 DOI: 10.1126/sciadv.aaz3595] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 05/05/2020] [Indexed: 05/23/2023]
Abstract
Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)2Te3 systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.
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Affiliation(s)
- Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xiaoyang Liu
- School of Information Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Qing Lin He
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Alexander Stern
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Gen Yin
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xiaoyu Che
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Qiming Shao
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Peng Zhang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peng Deng
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Chao-Yao Yang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Brian Casas
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
| | - Eun Sang Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-3706, USA
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA
| | - Xufeng Kou
- School of Information Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Kang L. Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA
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11
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Yuan Y, Wang X, Li H, Li J, Ji Y, Hao Z, Wu Y, He K, Wang Y, Xu Y, Duan W, Li W, Xue QK. Electronic States and Magnetic Response of MnBi 2Te 4 by Scanning Tunneling Microscopy and Spectroscopy. NANO LETTERS 2020; 20:3271-3277. [PMID: 32298117 DOI: 10.1021/acs.nanolett.0c00031] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Exotic quantum phenomena have been demonstrated in recently discovered intrinsic magnetic topological insulator MnBi2Te4. At its two-dimensional limit, the quantum anomalous Hall effect and axion insulator state were observed in odd and even layers of MnBi2Te4, respectively. Here, we employ low-temperature scanning tunneling microscopy to study the electronic properties of MnBi2Te4. The quasiparticle interference patterns indicate that the electronic structures on the topmost layer of MnBi2Te4 are different from those of the expected out-of-plane A-type antiferromagnetic phase. The topological surface states may be embedded in deeper layers beneath the topmost surface. Such novel electronic structure is presumably related to the modification of crystalline structure during sample cleaving and reorientation of the magnetic moment of Mn atoms near the surface. Mn dopants substituted at the Bi site on the second atomic layer are observed. The electronic structures fluctuate at atomic scale on the surface, which can affect the magnetism of MnBi2Te4.
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Affiliation(s)
- Yonghao Yuan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Xintong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Hao Li
- School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China
- Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Jiaheng Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Yu Ji
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Zhenqi Hao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
| | - Yang Wu
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Ke He
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Yayu Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Yong Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Wei Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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12
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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: 65] [Impact Index Per Article: 13.0] [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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13
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Kang SJ, Lee JW, Chung SH, Jang SY, Choi J, Suh KH, Kim YH, Ham YJ, Min KH. Synthesis and anti-tumor activity of imidazopyrazines as TAK1 inhibitors. Eur J Med Chem 2018; 163:660-670. [PMID: 30576901 DOI: 10.1016/j.ejmech.2018.12.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/15/2018] [Accepted: 12/11/2018] [Indexed: 10/27/2022]
Abstract
Transforming growth factor-β activated kinase-1 (TAK1) is a potential therapeutic target for cancers and inflammatory diseases. We synthesized a series of novel imidazopyrazine derivatives, which were found to exhibit potent inhibitory effect against TAK1. Compound 22a, which possesses a good pharmacokinetic profile, showed excellent in vitro kinase activity and significant in vivo efficacy in mice xenografted with SW620, a KRAS-dependent colon cancer cell line.
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Affiliation(s)
- Seok Jong Kang
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea; Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Jung Wuk Lee
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Shin Hyuck Chung
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sun Young Jang
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea; Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Jaeyul Choi
- Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Kwee Hyun Suh
- Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Young Hoon Kim
- Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Young Jin Ham
- Department of Drug Discovery, Hanmi Research Center, Gyeonggi-do, 18469, Republic of Korea
| | - Kyung Hoon Min
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea.
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14
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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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15
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Satake Y, Shiogai J, Takane D, Yamada K, Fujiwara K, Souma S, Sato T, Takahashi T, Tsukazaki A. Fermi-level tuning of the Dirac surface state in (Bi 1-x Sb x ) 2Se 3 thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:085501. [PMID: 29388559 DOI: 10.1088/1361-648x/aaa724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the electronic states and the transport properties of three-dimensional topological insulator (Bi1-x Sb x )2Se3 ternary alloy thin films grown on an isostructural Bi2Se3 buffer layer on InP substrates. By angle-resolved photoemission spectroscopy, we clearly detected Dirac surface states with a large bulk band gap of 0.2-0.3 eV in the (Bi1-x Sb x )2Se3 film with x = 0.70. In addition, we observed by Hall effect measurements that the dominant charge carrier converts from electron (n-type) to hole (p-type) at around x = 0.7, indicating that the Fermi level can be controlled across the Dirac point. Indeed, the carrier transport was shown to be governed by Dirac surface state in 0.63 ⩽ x ⩽ 0.75. These features suggest that Fermi-level tunable (Bi1-x Sb x )2Se3-based heterostructures provide a platform for extracting exotic topological phenomena.
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Affiliation(s)
- Yosuke Satake
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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16
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Fox EJ, Rosen IT, Yang Y, Jones GR, Elmquist RE, Kou X, Pan L, Wang KL, Goldhaber-Gordon D. Part-per-million quantization and current-induced breakdown of the quantum anomalous Hall effect. PHYSICAL REVIEW. B 2018; 98:10.1103/PhysRevB.98.075145. [PMID: 30984899 PMCID: PMC6459416 DOI: 10.1103/physrevb.98.075145] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In the quantum anomalous Hall effect, quantized Hall resistance and vanishing longitudinal resistivity are predicted to result from the presence of dissipationless, chiral edge states and an insulating two-dimensional bulk, without requiring an external magnetic field. Here, we explore the potential of this effect in magnetic topological insulator thin films for metrological applications. Using a cryogenic current comparator system, we measure quantization of the Hall resistance to within one part per million and, at lower current bias, longitudinal resistivity under 10 mΩ at zero magnetic field. Increasing the current density past a critical value leads to a breakdown of the quantized, low-dissipation state, which we attribute to electron heating in bulk current flow. We further investigate the prebreakdown regime by measuring transport dependence on temperature, current, and geometry, and find evidence for bulk dissipation, including thermal activation and possible variable-range hopping.
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Affiliation(s)
- E. J. Fox
- Department of Physics, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - I. T. Rosen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Yanfei Yang
- National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - George R. Jones
- National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Randolph E. Elmquist
- National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Xufeng Kou
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
- School of Information Science and Technology, ShanghaiTech University 201210, China
| | - Lei Pan
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Kang L. Wang
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - D. Goldhaber-Gordon
- Department of Physics, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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17
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Ou Y, Liu C, Jiang G, Feng Y, Zhao D, Wu W, Wang XX, Li W, Song C, Wang LL, Wang W, Wu W, Wang Y, He K, Ma XC, Xue QK. Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:1703062. [PMID: 29125706 DOI: 10.1002/adma.201703062] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/18/2017] [Indexed: 06/07/2023]
Abstract
The quantum anomalous Hall (QAH) effect, which has been realized in magnetic topological insulators (TIs), is the key to applications of dissipationless quantum Hall edge states in electronic devices. However, investigations and utilizations of the QAH effect are limited by the ultralow temperatures needed to reach full quantization-usually below 100 mK in either Cr- or V-doped (Bi,Sb)2 Te3 of the two experimentally confirmed QAH materials. Here it is shown that by codoping Cr and V magnetic elements in (Bi,Sb)2 Te3 TI, the temperature of the QAH effect can be significantly increased such that full quantization is achieved at 300 mK, and zero-field Hall resistance of 0.97 h/e2 is observed at 1.5 K. A systematic transport study of the codoped (Bi,Sb)2 Te3 films with varied Cr/V ratios reveals that magnetic codoping improves the homogeneity of ferromagnetism and modulates the surface band structure. This work demonstrates magnetic codoping to be an effective strategy for achieving high-temperature QAH effect in TIs.
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Affiliation(s)
- Yunbo Ou
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Chang Liu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Gaoyuan Jiang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Yang Feng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Dongyang Zhao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Weixiong Wu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Xiao-Xiao Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Wei Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Canli Song
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Li-Li Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Wenbo Wang
- Department of Physics and Astronomy, School of Arts and Sciences, Rutgers University, Piscataway, NJ, 08854, USA
| | - Weida Wu
- Department of Physics and Astronomy, School of Arts and Sciences, Rutgers University, Piscataway, NJ, 08854, USA
| | - Yayu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Ke He
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Xu-Cun Ma
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
| | - Qi-Kun Xue
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, P. R. China
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18
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Mahoney AC, Colless JI, Peeters L, Pauka SJ, Fox EJ, Kou X, Pan L, Wang KL, Goldhaber-Gordon D, Reilly DJ. Zero-field edge plasmons in a magnetic topological insulator. Nat Commun 2017; 8:1836. [PMID: 29184065 PMCID: PMC5705665 DOI: 10.1038/s41467-017-01984-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 10/30/2017] [Indexed: 11/21/2022] Open
Abstract
Incorporating ferromagnetic dopants into three-dimensional topological insulator thin films has recently led to the realisation of the quantum anomalous Hall effect. These materials are of great interest since they may support electrical currents that flow without resistance, even at zero magnetic field. To date, the quantum anomalous Hall effect has been investigated using low-frequency transport measurements. However, transport results can be difficult to interpret due to the presence of parallel conductive paths, or because additional non-chiral edge channels may exist. Here we move beyond transport measurements by probing the microwave response of a magnetised disk of Cr-(Bi,Sb)2Te3. We identify features associated with chiral edge plasmons, a signature that robust edge channels are intrinsic to this material system. Our results provide a measure of the velocity of edge excitations without contacting the sample, and pave the way for an on-chip circuit element of practical importance: the zero-field microwave circulator. Direct measurement of edge transport in the quantum anomalous Hall effect can be made difficult due to the presence of parallel conductive paths. Here, Mahoney et al. report features associated with chiral edge plasmons, a signature of robust edge states, by probing the zero-field microwave response of a magnetised disk of Cr-(Bi,Sb)2Te3.
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Affiliation(s)
- Alice C Mahoney
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - James I Colless
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia.,Department of Physics, University of California, Berkeley, CA, 94720, USA
| | - Lucas Peeters
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | - Sebastian J Pauka
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Eli J Fox
- Department of Physics, Stanford University, Stanford, CA, 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Xufeng Kou
- Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA.,School of Information Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Lei Pan
- 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
| | - David Goldhaber-Gordon
- Department of Physics, Stanford University, Stanford, CA, 94305, USA. .,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
| | - David J Reilly
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia. .,Microsoft Station Q Sydney, Sydney, NSW, 2006, Australia.
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19
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Kung HH, Maiti S, Wang X, Cheong SW, Maslov DL, Blumberg G. Chiral Spin Mode on the Surface of a Topological Insulator. PHYSICAL REVIEW LETTERS 2017; 119:136802. [PMID: 29341673 DOI: 10.1103/physrevlett.119.136802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Indexed: 05/05/2023]
Abstract
Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi_{2}Se_{3}. We observe a sharp peak at 150 meV in the pseudovector A_{2} symmetry channel of the Raman spectra. By comparing the data with calculations, we identify this peak as the transverse collective spin mode of surface Dirac fermions. This mode, unlike a Dirac plasmon or a surface plasmon in the charge sector of excitations, is analogous to a spin wave in a partially polarized Fermi liquid, with spin-orbit coupling playing the role of an effective magnetic field.
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Affiliation(s)
- H-H Kung
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S Maiti
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
| | - X Wang
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S-W Cheong
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA
| | - D L Maslov
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - G Blumberg
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
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20
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Kawamura M, Yoshimi R, Tsukazaki A, Takahashi KS, Kawasaki M, Tokura Y. Current-Driven Instability of the Quantum Anomalous Hall Effect in Ferromagnetic Topological Insulators. PHYSICAL REVIEW LETTERS 2017; 119:016803. [PMID: 28731731 DOI: 10.1103/physrevlett.119.016803] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Indexed: 06/07/2023]
Abstract
The instability of the quantum anomalous Hall (QAH) effect has been studied as a function of the electric current and temperature in ferromagnetic topological insulator thin films. We find that a characteristic current for the breakdown of the QAH effect is roughly proportional to the Hall-bar width, indicating that the Hall electric field is relevant to the breakdown. We also find that electron transport is dominated by variable range hopping (VRH) at low temperatures. Combining the current and temperature dependences of the conductivity in the VRH regime, the localization length of the QAH state is evaluated to be about 5 μm. The long localization length suggests a marginally insulating nature of the QAH state due to a large number of in-gap states.
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Affiliation(s)
- Minoru Kawamura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Ryutaro Yoshimi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Atsushi Tsukazaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Kei S Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075, Japan
| | - Masashi Kawasaki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum-phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
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