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Sahoo M, Onuorah IJ, Folkers LC, Kochetkova E, Chulkov EV, Otrokov MM, Aliev ZS, Amiraslanov IR, Wolter AUB, Büchner B, Corredor LT, Wang C, Salman Z, Isaeva A, De Renzi R, Allodi G. Ubiquitous Order-Disorder Transition in the Mn Antisite Sublattice of the (MnBi 2Te 4)(Bi 2Te 3) n Magnetic Topological Insulators. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2402753. [PMID: 38973332 PMCID: PMC11425889 DOI: 10.1002/advs.202402753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/22/2024] [Indexed: 07/09/2024]
Abstract
Magnetic topological insulators (TIs) herald a wealth of applications in spin-based technologies, relying on the novel quantum phenomena provided by their topological properties. Particularly promising is the (MnBi2Te4)(Bi2Te3)n layered family of established intrinsic magnetic TIs that can flexibly realize various magnetic orders and topological states. High tunability of this material platform is enabled by manganese-pnictogen intermixing, whose amounts and distribution patterns are controlled by synthetic conditions. Here, nuclear magnetic resonance and muon spin spectroscopy, sensitive local probe techniques, are employed to scrutinize the impact of the intermixing on the magnetic properties of (MnBi2Te4)(Bi2Te3)n and MnSb2Te4. The measurements not only confirm the opposite alignment between the Mn magnetic moments on native sites and antisites in the ground state of MnSb2Te4, but for the first time directly show the same alignment in (MnBi2Te4)(Bi2Te3)n with n = 0, 1 and 2. Moreover, for all compounds, the static magnetic moment of the Mn antisite sublattice is found to disappear well below the intrinsic magnetic transition temperature, leaving a homogeneous magnetic structure undisturbed by the intermixing. The findings provide a microscopic understanding of the crucial role played by Mn-Bi intermixing in (MnBi2Te4)(Bi2Te3)n and offer pathways to optimizing the magnetic gap in its surface states.
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Affiliation(s)
- Manaswini Sahoo
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Ifeanyi John Onuorah
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Laura Christina Folkers
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | - Ekaterina Kochetkova
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Van der Waals-Zeeman Institute, Department of Physics and Astronomy, University of Amsterdam, Science Park 094, Amsterdam, 1098 XH, Netherlands
| | - Evgueni V Chulkov
- Donostia International Physics Center, Sebastián, 20018 Donostia-San, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco UPV/EHU, Donostia-San Sebastián, 20018, Spain
- Centro de Física de Materiales (CFM-MPC), Centro Mixto (CSIC-UPV/EHU), Donostia-San Sebastián, 20018, Spain
- Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Mikhail M Otrokov
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
| | - Ziya S Aliev
- Baku State University, Baku, AZ1148, Azerbaijan
- Institute of Physics Ministry of Science and Education Republic of Azerbaijan, Baku, AZ1143, Azerbaijan
| | - Imamaddin R Amiraslanov
- Baku State University, Baku, AZ1148, Azerbaijan
- Institute of Physics Ministry of Science and Education Republic of Azerbaijan, Baku, AZ1143, Azerbaijan
| | - Anja U B Wolter
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
| | - Bernd Büchner
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
| | | | - Chennan Wang
- Laboratory for Muon Spin Spectroscopy, Paul-Scherrer-Institute, Villigen PSI, CH-5232, Switzerland
| | - Zaher Salman
- Laboratory for Muon Spin Spectroscopy, Paul-Scherrer-Institute, Villigen PSI, CH-5232, Switzerland
| | - Anna Isaeva
- Leibniz IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany
- Van der Waals-Zeeman Institute, Department of Physics and Astronomy, University of Amsterdam, Science Park 094, Amsterdam, 1098 XH, Netherlands
- Faculty of Physics, Technical University of Dortmund, Otto-Hahn-Str. 4, 44221, Dortmund, Germany
- Research Center Future Energy Materials and Systems (RC FEMS), Germany
| | - Roberto De Renzi
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
| | - Giuseppe Allodi
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universitá di Parma, Parco delle Scienze 7A, Parma, I-43124, Italy
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Li Q, Mo SK, Edmonds MT. Recent progress of MnBi 2Te 4 epitaxial thin films as a platform for realising the quantum anomalous Hall effect. NANOSCALE 2024; 16:14247-14260. [PMID: 39015951 DOI: 10.1039/d4nr00194j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Since the first realisation of the quantum anomalous Hall effect (QAHE) in a dilute magnetic-doped topological insulator thin film in 2013, the quantisation temperature has been limited to less than 1 K due to magnetic disorder in dilute magnetic systems. With magnetic moments ordered into the crystal lattice, the intrinsic magnetic topological insulator MnBi2Te4 has the potential to eliminate or significantly reduce magnetic disorder and improve the quantisation temperature. Surprisingly, to date, the QAHE has yet to be observed in molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films at zero magnetic field, and what leads to the difficulty in quantisation is still an active research area. Although bulk MnBi2Te4 and exfoliated flakes have been well studied, revealing both the QAHE and axion insulator phases, experimental progress on MBE thin films has been slower. Understanding how the breakdown of the QAHE occurs in MnBi2Te4 thin films and finding solutions that will enable mass-produced millimetre-size QAHE devices operating at elevated temperatures are required. In this mini-review, we will summarise recent studies on the electronic and magnetic properties of MBE MnBi2Te4 thin films and discuss mechanisms that could explain the failure of the QAHE from the aspects of defects, electronic structure, magnetic order, and consequences of their delicate interplay. Finally, we propose several strategies for realising the QAHE at elevated temperatures in MnBi2Te4 thin films.
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Affiliation(s)
- Qile Li
- School of Physics and Astronomy, Monash University, Clayton, VIC, Australia.
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, Australia
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Mark T Edmonds
- School of Physics and Astronomy, Monash University, Clayton, VIC, Australia.
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, VIC, Australia
- ANFF-VIC Technology Fellow, Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, VIC 3168, Australia
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3
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Li Q, Di Bernardo I, Maniatis J, McEwen D, Dominguez-Celorrio A, Bhuiyan MTH, Zhao M, Tadich A, Watson L, Lowe B, Vu THY, Trang CX, Hwang J, Mo SK, Fuhrer MS, Edmonds MT. Imaging the Breakdown and Restoration of Topological Protection in Magnetic Topological Insulator MnBi 2Te 4. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312004. [PMID: 38402422 DOI: 10.1002/adma.202312004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 02/20/2024] [Indexed: 02/26/2024]
Abstract
Quantum anomalous Hall (QAH) insulators transport charge without resistance along topologically protected chiral 1D edge states. Yet, in magnetic topological insulators to date, topological protection is far from robust, with zero-magnetic field QAH effect only realized at temperatures an order of magnitude below the Néel temperature TN, though small magnetic fields can stabilize QAH effect. Understanding why topological protection breaks down is therefore essential to realizing QAH effect at higher temperatures. Here a scanning tunneling microscope is used to directly map the size of exchange gap (Eg,ex) and its spatial fluctuation in the QAH insulator 5-layer MnBi2Te4. Long-range fluctuations of Eg,ex are observed, with values ranging between 0 (gapless) and 70 meV, appearing to be uncorrelated to individual surface point defects. The breakdown of topological protection is directly imaged, showing that the gapless edge state, the hallmark signature of a QAH insulator, hybridizes with extended gapless regions in the bulk. Finally, it is unambiguously demonstrated that the gapless regions originate from magnetic disorder, by demonstrating that a small magnetic field restores Eg,ex in these regions, explaining the recovery of topological protection in magnetic fields. The results indicate that overcoming magnetic disorder is the key to exploiting the unique properties of QAH insulators.
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Affiliation(s)
- Qile Li
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Iolanda Di Bernardo
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Johnathon Maniatis
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
| | - Daniel McEwen
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Amelia Dominguez-Celorrio
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Mohammad T H Bhuiyan
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
| | - Mengting Zhao
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
- Australian Synchrotron, Clayton, Victoria, 3168, Australia
| | - Anton Tadich
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid, 28049, Spain
| | - Liam Watson
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Benjamin Lowe
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Thi-Hai-Yen Vu
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
| | - Chi Xuan Trang
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Jinwoong Hwang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Michael S Fuhrer
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
| | - Mark T Edmonds
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3168, Australia
- ARC Centre for Future Low Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
- ANFF-VIC Technology Fellow, Melbourne Centre for Nanofabrication, Victorian Node of, the Australian National Fabrication Facility, Clayton, Victoria, 3168, Australia
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Webb TA, Tamanna AN, Ding X, Verma N, Xu J, Krusin-Elbaum L, Dean CR, Basov DN, Pasupathy AN. Tunable Magnetic Domains in Ferrimagnetic MnSb 2Te 4. NANO LETTERS 2024; 24:4393-4399. [PMID: 38569084 DOI: 10.1021/acs.nanolett.3c05058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Highly tunable properties make Mn(Bi,Sb)2Te4 a rich playground for exploring the interplay between band topology and magnetism: On one end, MnBi2Te4 is an antiferromagnetic topological insulator, while the magnetic structure of MnSb2Te4 (MST) can be tuned between antiferromagnetic and ferrimagnetic. Motivated to control electronic properties through real-space magnetic textures, we use magnetic force microscopy (MFM) to image the domains of ferrimagnetic MST. We find that magnetic field tunes between stripe and bubble domain morphologies, raising the possibility of topological spin textures. Moreover, we combine in situ transport with domain manipulation and imaging to both write MST device properties and directly measure the scaling of the Hall response with the domain area. This work demonstrates measurement of the local anomalous Hall response using MFM and opens the door to reconfigurable domain-based devices in the M(B,S)T family.
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Affiliation(s)
- Tatiana A Webb
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Afrin N Tamanna
- Department of Physics, The City College of New York, New York, New York 10027, United States
| | - Xiaxin Ding
- Department of Physics, The City College of New York, New York, New York 10027, United States
| | - Nishchhal Verma
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Jikai Xu
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Lia Krusin-Elbaum
- Department of Physics, The City College of New York, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Dmitri N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, New York 10027, United States
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, New York 11973, United States
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5
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Hu C, Qian T, Ni N. Recent progress in MnBi 2nTe 3n+1 intrinsic magnetic topological insulators: crystal growth, magnetism and chemical disorder. Natl Sci Rev 2024; 11:nwad282. [PMID: 38213523 PMCID: PMC10776370 DOI: 10.1093/nsr/nwad282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/19/2023] [Accepted: 09/06/2023] [Indexed: 01/13/2024] Open
Abstract
The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators, etc. To date, the MnBi2nTe3n+1 family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.
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Affiliation(s)
- Chaowei Hu
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Tiema Qian
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Ni Ni
- Department of Physics and Astronomy and California NanoSystems Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
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6
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Shikin AM, Estyunina TP, Eryzhenkov AV, Zaitsev NL, Tarasov AV. Topological phase transition in the antiferromagnetic topological insulator MnBi[Formula: see text]Te[Formula: see text] from the point of view of axion-like state realization. Sci Rep 2023; 13:16343. [PMID: 37770454 PMCID: PMC10539541 DOI: 10.1038/s41598-023-42466-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/11/2023] [Indexed: 09/30/2023] Open
Abstract
This work aims to study the conditions of topological phase transition (TPT) between the topological and trivial states in the antiferromagnetic topological insulator (AFM TI) MnBi[Formula: see text]Te[Formula: see text] and propose some theory about the relationship of this TPT with the possibility of axion-like state realization in this material. Using the density functional approach we have analyzed the changes in the electronic and spin structure of topological surface states (TSSs) and the nearest conduction and valence bands (CB and VB) including the changes in the bulk band gap as well as the Dirac point (DP) gap in TSSs under variation of the spin-orbit coupling strength in the region of the TPT for infinite crystal and slab with a surface both. We have shown that in both cases the TPT occurs with inversion of the contributions of the Bi-[Formula: see text] and Te-[Formula: see text] states of different parity at the gap edges related to change in the gap sign. In the case of surface calculations, the Bi-[Formula: see text] and Te-[Formula: see text] states at the edges of the bulk band gap and their inversion at the TPT point are transformed into the TSSs with an energy gap at the DP. In this case the TPT takes place without closing the band gap, i.e. with a "jump" through zero and the formation of the nonzero gap during such a transition. Our calculations show that the TPT point is also characterized by an inversion of the out-of-plane spin polarization [Formula: see text] at the [Formula: see text] point for lower and upper parts of the Dirac cone and a significant spatial redistribution of the TSSs between the surface and the bulk. We suppose that the nonzero Dirac gap can have some relationship with the formation of the axion-like state, which presumably couples nonmagnetic spin-orbit and magnetic contributions at the boundary between the topological and trivial phases for a system with parameters close to the TPT conditions. A practically realized system is proposed - the AFM TI with a stoichiometry close to that of MnBi[Formula: see text]Te[Formula: see text]Se[Formula: see text] with partial (about 50%) substitution of Te atoms for Se atoms in MnBi[Formula: see text]Te[Formula: see text] which can be an experimental platform for the implementation and experimental analysis of the TPT and the corresponding possibility of the axion-like state realization in Condensed Matter. Besides, such system could serve as a good platform for studying the dynamic axion effect, where the axion field fluctuations are maximised when a small external field is applied to the system which state is close to the TPT.
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Affiliation(s)
- A. M. Shikin
- St. Petersburg State University, St. Petersburg, Russia 198504
| | - T. P. Estyunina
- St. Petersburg State University, St. Petersburg, Russia 198504
| | | | - N. L. Zaitsev
- St. Petersburg State University, St. Petersburg, Russia 198504
- Institute of Molecule and Crystal Physics, Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Ufa, Russia 450075
| | - A. V. Tarasov
- St. Petersburg State University, St. Petersburg, Russia 198504
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7
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Islam F, Lee Y, Pajerowski DM, Oh J, Tian W, Zhou L, Yan J, Ke L, McQueeney RJ, Vaknin D. Role of Magnetic Defects in Tuning Ground States of Magnetic Topological Insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209951. [PMID: 36731511 DOI: 10.1002/adma.202209951] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/23/2023] [Indexed: 05/26/2023]
Abstract
Magnetic defects play an important, but poorly understood, role in magnetic topological insulators (TIs). For example, topological surface transport and bulk magnetic properties are controlled by magnetic defects in Bi2 Se3 -based dilute ferromagnetic (FM) TIs and MnBi2 Te4 (MBT)-based antiferromagnetic (AFM) TIs. Despite its nascent ferromagnetism, the inelastic neutron scattering data show that a fraction of the Mn defects in Sb2 Te3 form strong AFM dimer singlets within a quintuple block. The AFM superexchange coupling occurs via Mn-Te-Mn linear bonds and is identical to the AFM coupling between antisite defects and the FM Mn layer in MBT, establishing common interactions in the two materials classes. It is also found that the FM correlations in (Sb1-x Mnx )2 Te3 are likely driven by magnetic defects in adjacent quintuple blocks across the van der Waals gap. In addition to providing answers to long-standing questions about the evolution of FM order in dilute TI, these results also show that the evolution of global magnetic order from AFM to FM in Sb-substituted MBT is controlled by defect engineering of the intrablock and interblock coupling.
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Affiliation(s)
- Farhan Islam
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
| | - Yongbin Lee
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
| | - Daniel M Pajerowski
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - JinSu Oh
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
| | - Wei Tian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Lin Zhou
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
- Department of Materials Science and Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Jiaqiang Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Liqin Ke
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
| | - Robert J McQueeney
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
| | - David Vaknin
- Division of Materials Sciences and Engineering, Ames National Laboratory, Ames, IA, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
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8
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Tan H, Yan B. Distinct Magnetic Gaps between Antiferromagnetic and Ferromagnetic Orders Driven by Surface Defects in the Topological Magnet MnBi_{2}Te_{4}. PHYSICAL REVIEW LETTERS 2023; 130:126702. [PMID: 37027867 DOI: 10.1103/physrevlett.130.126702] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 03/03/2023] [Indexed: 06/09/2023]
Abstract
Many experiments observed a metallic behavior at zero magnetic fields (antiferromagnetic phase, AFM) in MnBi_{2}Te_{4} thin film transport, which coincides with gapless surface states observed by angle-resolved photoemission spectroscopy, while it can become a Chern insulator at field larger than 6 T (ferromagnetic phase, FM). Thus, the zero-field surface magnetism was once speculated to be different from the bulk AFM phase. However, recent magnetic force microscopy refutes this assumption by detecting persistent AFM order on the surface. In this Letter, we propose a mechanism related to surface defects that can rationalize these contradicting observations in different experiments. We find that co-antisites (exchanging Mn and Bi atoms in the surface van der Waals layer) can strongly suppress the magnetic gap down to several meV in the AFM phase without violating the magnetic order but preserve the magnetic gap in the FM phase. The different gap sizes between AFM and FM phases are caused by the exchange interaction cancellation or collaboration of the top two van der Waals layers manifested by defect-induced surface charge redistribution among the top two van der Waals layers. This theory can be validated by the position- and field-dependent gap in future surface spectroscopy measurements. Our work suggests suppressing related defects in samples to realize the quantum anomalous Hall insulator or axion insulator at zero fields.
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Affiliation(s)
- Hengxin Tan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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