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Nadeem M, Wang X. Spin Gapless Quantum Materials and Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2402503. [PMID: 38962884 DOI: 10.1002/adma.202402503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 06/04/2024] [Indexed: 07/05/2024]
Abstract
Quantum materials, with nontrivial quantum phenomena and mechanisms, promise efficient quantum technologies with enhanced functionalities. Quantum technology is held back because a gap between fundamental science and its implementation is not fully understood yet. In order to capitalize the quantum advantage, a new perspective is required to figure out and close this gap. In this review, spin gapless quantum materials, featured by fully spin-polarized bands and the electron/hole transport, are discussed from the perspective of fundamental understanding and device applications. Spin gapless quantum materials can be simulated by minimal two-band models and could help to understand band structure engineering in various topological quantum materials discovered so far. It is explicitly highlighted that various types of spin gapless band dispersion are fundamental ingredients to understand quantum anomalous Hall effect. Based on conventional transport in the bulk and topological transport on the boundaries, various spintronic device aspects of spin gapless quantum materials as well as their advantages in different models for topological field effect transistors are reviewed.
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Affiliation(s)
- Muhammad Nadeem
- Institute for Superconducting and Electronic Materials (ISEM), Faculty of Engineering and Information Sciences (EIS), University of Wollongong, Wollongong, New South Wales, 2525, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, Wollongong, New South Wales, 2525, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials (ISEM), Faculty of Engineering and Information Sciences (EIS), University of Wollongong, Wollongong, New South Wales, 2525, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, Wollongong, New South Wales, 2525, Australia
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2
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Xu Z, Duan W, Xu Y. Controllable Chirality and Band Gap of Quantum Anomalous Hall Insulators. NANO LETTERS 2023; 23:305-311. [PMID: 36537751 DOI: 10.1021/acs.nanolett.2c04369] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Finding guiding principles to optimize properties of quantum anomalous Hall (QAH) insulators is of pivotal importance to fundamental science and applications. Here, we build a first-principles QAH material database of chirality and band gap, explore microscopic mechanisms determining the QAH material properties, and obtain a general physical picture that can help researchers comprehensively understand the QAH data. Our results reveal that the usually neglected Coulomb exchange is unexpectedly strong in a large class of QAH materials, which is the key to resolve experimental puzzles. Moreover, we identify simple indicators for property evaluation and suggest material design strategies to control QAH chirality and gap by tuning cooperative or competing contributions via magnetic codoping, heterostructuring, spin-orbit proximity, etc. The work is valuable to future research of magnetic topological physics and materials.
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Affiliation(s)
- Zhiming Xu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
| | - Wenhui Duan
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong518057, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing100084, China
- Institute for Advanced Study, Tsinghua University, Beijing100084, China
- Beijing Academy of Quantum Information Sciences, Beijing100193, China
| | - Yong Xu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing100084, China
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong518057, China
- Frontier Science Center for Quantum Information, Beijing100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing100084, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama351-0198, Japan
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3
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Zhang H, Zhang J, Zhang Y, Yang W, Wang Y, Xu X, Liu F. A generic dual d-band model for interlayer ferromagnetic coupling in a transition-metal doped MnBi 2Te 4 family of materials. NANOSCALE 2022; 14:13689-13695. [PMID: 36093811 DOI: 10.1039/d2nr03283j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Realization of ferromagnetic (FM) interlayer coupling in magnetic topological insulators (TIs) of the MnBi2Te4 family of materials (MBTs) may pave the way for realizing the high-temperature quantum anomalous Hall effect (high-T QAHE). Here we propose a generic dual d-band (DDB) model to elucidate the energy difference (ΔE = EAFM - EFM) between the AFM and FM coupling in transition-metal (TM)-doped MBTs, where the valence of TMs splits into d-t2g and d-eg sub-bands. Remarkably, the DDB shows that ΔE is universally determined by the relative position of the dopant (X) and Mn d-eg/t2g bands, . If ΔEd > 0, then ΔE > 0 and the desired FM coupling is favored. This surprisingly simple rule is confirmed by first-principles calculations of hole-type 3d and 4d TM dopants. Significantly, by applying the DDB model, we predict the high-T QAHE in the V-doped Mn2Bi2Te5, where the Curie temperature is enhanced by doubling of the MnTe layer, while the topological order mitigated by doping can be restored by strain.
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Affiliation(s)
- Huisheng Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Jingjing Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Yaling Zhang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Wenjia Yang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Yingying Wang
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Xiaohong Xu
- College of Physics and Electronic Information & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & Research Institute of Materials Science, Shanxi Normal University, Taiyuan, 030031, China.
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
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Liu L, Huan H, Xue Y, Bao H, Yang Z. Anisotropy-induced phase transitions in an intrinsic half-Chern insulator Ni 2I 2. NANOSCALE 2022; 14:13378-13388. [PMID: 36069434 DOI: 10.1039/d2nr02599j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
One crucial target of research on spintronics is to achieve flexibly tunable and highly efficient spin-polarized electronic current. In this work, by using first-principles calculations and topological characterization theories, we propose an intrinsic half-Chern insulator (HCI) in a Ni2I2 monolayer, which possesses 100% spin-polarized topologically nontrivial edge states, distinct from ordinary Chern insulators. Its band gap is formed due to the lifting of the double degeneracy of non-Dirac bands composed of Ni dxz/dyz orbitals. The HCI becomes a half semiconductor (HS) or a combined state of a half metal (HM) and an HCI if biaxial strain is applied. The phase transition is found to be associated with the unique anisotropy of the bands, originating from the diverse orbital distributions and the opposite moving in energy of Ni dxy and dxz/dyz bands under the strain. Our findings demonstrate that the monolayer Ni2I2 is a unique Chern insulator with ideal spintronic properties, supporting versatile applications in spintronic devices with very high spin polarization and extremely low-power dissipation.
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Affiliation(s)
- Lei Liu
- State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
- Shanghai Qi Zhi Institute, Shanghai 200030, China
| | - Hao Huan
- State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
- Shanghai Qi Zhi Institute, Shanghai 200030, China
| | - Yang Xue
- State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
- School of Science, East China University of Science and Technology, Shanghai 200237, China
| | - Hairui Bao
- State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
- Shanghai Qi Zhi Institute, Shanghai 200030, China
| | - Zhongqin Yang
- State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
- Shanghai Qi Zhi Institute, Shanghai 200030, China
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5
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Li Z, Han Y, Qiao Z. Chern Number Tunable Quantum Anomalous Hall Effect in Monolayer Transitional Metal Oxides via Manipulating Magnetization Orientation. PHYSICAL REVIEW LETTERS 2022; 129:036801. [PMID: 35905371 DOI: 10.1103/physrevlett.129.036801] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/06/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Although much effort has been made to explore quantum anomalous Hall effect (QAHE) in both theory and experiment, the QAHE systems with tunable Chern numbers are yet limited. Here, we theoretically propose that NiAsO_{3} and PdSbO_{3}, monolayer transitional metal oxides, can realize QAHE with tunable Chern numbers via manipulating their magnetization orientations. When the magnetization lies in the x-y plane and all mirror symmetries are broken, the low-Chern-number (i.e., C=±1) phase emerges. When the magnetization exhibits nonzero z-direction component, the system enters the high-Chern-number (i.e., C=±3) phase, even in the presence of canted magnetization. The global band gap can approach the room-temperature energy scale in monolayer PdSbO_{3} (23.4 meV), when the magnetization is aligned to z direction. By using Wannier-based tight-binding model, we establish the phase diagram of magnetization induced topological phase transition. Our work provides a high-temperature QAHE system with tunable Chern number for the practical electronic application.
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Affiliation(s)
- Zeyu Li
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yulei Han
- Department of Physics, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Zhenhua Qiao
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- ICQD, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
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6
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Zhang L, Park C, Yoon M. Quantum Phase Engineering of Two-Dimensional Post-Transition Metals by Substrates: Toward a Room-Temperature Quantum Anomalous Hall Insulator. NANO LETTERS 2020; 20:7186-7192. [PMID: 32930599 DOI: 10.1021/acs.nanolett.0c02520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We propose a new strategy to engineer topological and magnetic properties of two-dimensional (2D) hexagonal lattices consisting of post-transition metals. Our first-principles calculations demonstrate that substrates serve as templates to form 2D lattices with high thermodynamic stability, where their topological properties as well as magnetic properties sensitively change as a function of lattice constants, i.e., the system undergoes a first-order phase transition from nonmagnetic to ferromagnetic state above a critical lattice constant. Consequently, substrates can be used to explore versatile magnetic, electronic, and quantum topological properties. We establish phase diagrams of versatile quantum phases in terms of exchange coupling and spin-orbit coupling effectively tuned by the lattice constants. We further reveal the first room-temperature quantum anomalous Hall (QAH) effect, i.e., Sn on 2√3 × 2√3 graphane is a QAH insulator with a large spin-orbit coupling gap of ∼0.2 eV and a Curie temperature of ∼380 K by using the 2D anisotropic Heisenberg model.
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Affiliation(s)
- Lizhi Zhang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37916, United States
| | - Changwon Park
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37916, United States
| | - Mina Yoon
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37916, United States
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7
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Nadeem M, Hamilton AR, Fuhrer MS, Wang X. Quantum Anomalous Hall Effect in Magnetic Doped Topological Insulators and Ferromagnetic Spin-Gapless Semiconductors-A Perspective Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1904322. [PMID: 32914584 DOI: 10.1002/smll.201904322] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 06/07/2020] [Indexed: 06/11/2023]
Abstract
Quantum anomalous Hall effect, with a trademark of dissipationless chiral edge states for electronics/spintronics transport applications, can be realized in materials with large spin-orbit coupling and strong intrinsic magnetization. After Haldane's seminal proposal, several models have been presented to control/enhance the spin-orbit coupling and intrinsic magnetic exchange interaction. After brief introduction of Haldane model for spineless fermions, following three fundamental quantum anomalous Hall models are discussed in this perspective review: i) low-energy effective four band model for magnetic-doped topological insulator (Bi,Sb)2 Te3 thin films, ii) four band tight-binding model for graphene with magnetic adatoms, and iii) two (three) band spinful tight-binding model for ferromagnetic spin-gapless semiconductors with honeycomb (kagome) lattice where ground state is intrinsically ferromagnetic. These models cover 2D Dirac materials hosting spinless, spinful, and spin-degenerate Dirac points where various mass terms open bandgap and lead to quantum anomalous Hall effect. With emphasis on the topological phase transition driven by ferromagnetic exchange interaction and its interplay with spin-orbit-coupling, various symmetry constraints on the nature of mass term and the materialization of these models are discussed. This study will shed light on the fundamental theoretical perspectives of quantum anomalous Hall materials.
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Affiliation(s)
- Muhammad Nadeem
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, New South Wales, 2525, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, Wollongong, New South Wales, 2525, Australia
- Department of Basic Sciences, School of Electrical Engineering and Computer Science, National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan
| | - Alex R Hamilton
- School of Physics, University of New South Wales, Sydney, New South Wales, 2052, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Michael S Fuhrer
- School of Physics and Astronomy, Monash University, Monash, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), Monash University, Monash, Victoria, 3800, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, New South Wales, 2525, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, Wollongong, New South Wales, 2525, Australia
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8
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Plucinski L. Band structure engineering in 3D topological insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:183001. [PMID: 30731442 DOI: 10.1088/1361-648x/ab052c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The discovery of novel topological phases has revolutionized the way we think about electronic matter. Topologically protected states have been demonstrated for many materials, however, creating materials that exhibit desired properties often remains a challenge. For example, one of the key challenges in three dimensional topological insulators has been the realization of insulating bulk, such that the unique properties of surface states could be fully employed in electron transport applications. Further challenges are in creating materials that simultaneously exhibit states protected by various symmetries on their different surfaces, inducing magnetic exchange coupling into the topological materials, as well as potentially creating non-trivial transient electronic states. This review presents theoretical concepts and a selection of experimental results from the point view of a spectroscopist, and as such might be useful for physicists who want to get familiar with the key concepts in a self-contained form with formalism reduced to readily understandable concepts.
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Affiliation(s)
- L Plucinski
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich, D-52425 Jülich, Germany. Jülich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), 52425 Jülich, Germany
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9
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Liu J, Meng S, Sun JT. Spin-Orientation-Dependent Topological States in Two-Dimensional Antiferromagnetic NiTl 2S 4 Monolayers. NANO LETTERS 2019; 19:3321-3326. [PMID: 31020845 DOI: 10.1021/acs.nanolett.9b00948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The topological states of matter arising from the nontrivial magnetic configuration provide a better understanding of physical properties and functionalities of solid materials. Such studies benefit from the active control of spin orientation in any solid, which is known to take place rarely in the two-dimensional (2D) limit. Here we demonstrate by the first-principles calculations that spin-orientation-dependent topological states can appear in the geometrically frustrated monolayer antiferromagnet (AFM). Different topological states including the quantum anomalous Hall (QAH) effect and time-reversal-symmetry (TRS) broken quantum spin Hall (QSH) effect can be obtained by changing the spin orientation in the NiTl2S4 monolayer. Remarkably, the dilated nc-AFM NiTl2S4 monolayer gives birth to the QAH effect with the hitherto reported largest number of quantized conducting channels (Chern number [Formula: see text] = -4) in 2D materials. Interestingly, under tunable chemical potential, the nc-AFM NiTl2S4 monolayer hosts a novel state supporting the coexistence of QAH and TRS broken QSH effects with a Chern number of [Formula: see text] = 3 and a spin Chern number of [Formula: see text] = 1. This work manifests a promising concept and material realization of topological spintronics in 2D antiferromagnets by manipulating their spin degree of freedom.
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Affiliation(s)
- Jian Liu
- Beijing National Laboratory of Condensed Matter Physics , and Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Sheng Meng
- Beijing National Laboratory of Condensed Matter Physics , and Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
- Collaborative Innovation Center of Quantum Matter , Beijing , 100190 , P. R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P. R. China
| | - Jia-Tao Sun
- Beijing National Laboratory of Condensed Matter Physics , and Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Information and Electronics , Beijing Institute of Technology , Beijing 100081 , P. R. China
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10
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Zhang KC, Li YF, Liu Y, Zhu Y. Realizing both giant magnetic anisotropy and quantum anomalous Hall effect in graphene with adsorbed Te-Co dimer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:045802. [PMID: 30523999 DOI: 10.1088/1361-648x/aaf212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To realize quantum anomalous Hall state at higher temperature, it needs to search for the magnetic topological insulators with giant magnetic anisotropy. We have studied the structural, magnetic and topological properties of graphene with adsorbed Te-A (A [Formula: see text] Co, Rh, Ir) dimers by first-principles calculations and Wannier technique. Our results reveal that the system of Te-Co@G is an excellent magnetic topological insulator with both perpendicular magnetic anisotropy of 61.7 meV and large topological band-gap of 35.8 meV. Both the magnetic anisotropy and the band-gap can be effectively tuned by the applied electric field. The dimers are stably adsorbed onto the graphene and the systems are robust against thermal fluctuation. Topological analysis reveals that the adsorption system is the Chern insulator with [Formula: see text].
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Affiliation(s)
- Kai-Cheng Zhang
- College of Mathematics and Physics, Bohai University, Jinzhou 121013, People's Republic of China
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11
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Li P. Prediction of intrinsic two dimensional ferromagnetism realized quantum anomalous Hall effect. Phys Chem Chem Phys 2019; 21:6712-6717. [DOI: 10.1039/c8cp07781a] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The monolayer of FeX3 (X = Cl, Br, I) possesses a quantum anomalous Hall insulating phase generated by the honeycomb lattice of iron atoms.
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Affiliation(s)
- Ping Li
- School of Physical Science and Technology
- Soochow University
- Suzhou 215006
- People's Republic of China
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12
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Lado JL, Sigrist M. Two-Dimensional Topological Superconductivity with Antiferromagnetic Insulators. PHYSICAL REVIEW LETTERS 2018; 121:037002. [PMID: 30085778 DOI: 10.1103/physrevlett.121.037002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Indexed: 06/08/2023]
Abstract
Two-dimensional topological superconductivity has attracted great interest due to the emergence of Majorana modes bound to vortices and propagating along edges. However, due to its rare appearance in natural compounds, experimental realizations rely on a delicate artificial engineering involving materials with helical states, magnetic fields, and conventional superconductors. Here we introduce an alternative path using a class of three-dimensional antiferromagnets to engineer a two-dimensional topological superconductor. Our proposal exploits the appearance of solitonic states at the interface between a topologically trivial antiferromagnet and a conventional superconductor, which realize a topological superconducting phase when their spectrum is gapped by intrinsic spin-orbit coupling. We show that these interfacial states do not require fine-tuning, but are protected by asymptotic boundary conditions.
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Affiliation(s)
- J L Lado
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - M Sigrist
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
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13
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Xue Y, Zhang JY, Zhao B, Wei XY, Yang ZQ. Non-Dirac Chern insulators with large band gaps and spin-polarized edge states. NANOSCALE 2018; 10:8569-8577. [PMID: 29693673 DOI: 10.1039/c8nr00201k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Based on first-principles calculations and k·p models, we demonstrate that PbC/MnSe heterostructures are a non-Dirac type of Chern insulator with very large band gaps (244 meV) and exotically half-metallic edge states, providing the possibilities of realizing very robust, completely spin polarized, and dissipationless spintronic devices from the heterostructures. The achieved extraordinarily large nontrivial band gap can be ascribed to the contribution of the non-Dirac type electrons (composed of px and py) and the very strong atomic spin-orbit coupling (SOC) interaction of the heavy Pb element in the system. Surprisingly, the band structures are found to be sensitive to the different exchange and correlation functionals adopted in the first-principles calculations. Chern insulators with various mechanisms are acquired from them. These discoveries show that the predicted nontrivial topology in PbC/MnSe heterostructures is robust and can be observed in experiments at high temperatures. The system has great potential to have attractive applications in future spintronics.
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Affiliation(s)
- Y Xue
- State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) & Department of Physics, Fudan University, Shanghai 200433, China.
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14
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Kong X, Li L, Leenaerts O, Wang W, Liu XJ, Peeters FM. Quantum anomalous Hall effect in a stable 1T-YN 2 monolayer with a large nontrivial bandgap and a high Chern number. NANOSCALE 2018; 10:8153-8161. [PMID: 29676423 DOI: 10.1039/c8nr00571k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase, characterized by a non-zero Chern number defined in the bulk and chiral edge states in the boundary. Using first-principles calculations, we demonstrate the presence of the QAH effect in a 1T-YN2 monolayer, which was recently predicted to be a Dirac half metal without spin-orbit coupling (SOC). We show that the inclusion of SOC opens up a large nontrivial bandgap of nearly 0.1 eV in the electronic band structure. This results in the nontrivial bulk topology, which is confirmed by the calculation of Berry curvature, anomalous Hall conductance and the presence of chiral edge states. Remarkably, a QAH phase of high Chern number C = 3 is found, and there are three corresponding gapless chiral edge states emerging inside the bulk gap. Different substrates are also chosen to study the possible experimental realization of the 1T-YN2 monolayer, while retaining its nontrivial topological properties. Our results open a new avenue in searching for QAH insulators with high temperature and high Chern numbers, which can have nontrivial practical applications.
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Affiliation(s)
- Xiangru Kong
- International Center for Quantum Materials, School of Physics, Peking University, and Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China
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15
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Jiang K, Zhou S, Dai X, Wang Z. Antiferromagnetic Chern Insulators in Noncentrosymmetric Systems. PHYSICAL REVIEW LETTERS 2018; 120:157205. [PMID: 29756861 DOI: 10.1103/physrevlett.120.157205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Indexed: 06/08/2023]
Abstract
We investigate a new class of topological antiferromagnetic (AF) Chern insulators driven by electronic interactions in two-dimensional systems without inversion symmetry. Despite the absence of a net magnetization, AF Chern insulators (AFCI) possess a nonzero Chern number C and exhibit the quantum anomalous Hall effect (QAHE). Their existence is guaranteed by the bifurcation of the boundary line of Weyl points between a quantum spin Hall insulator and a topologically trivial phase with the emergence of AF long-range order. As a concrete example, we study the phase structure of the honeycomb lattice Kane-Mele model as a function of the inversion-breaking ionic potential and the Hubbard interaction. We find an easy z axis C=1 AFCI phase and a spin-flop transition to a topologically trivial xy plane collinear antiferromagnet. We propose experimental realizations of the AFCI and QAHE in correlated electron materials and cold atom systems.
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Affiliation(s)
- Kun Jiang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Sen Zhou
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xi Dai
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Ziqiang Wang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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Zhang KC, Li YF, Liu Y, Zhu Y. Protecting quantum anomalous Hall state from thermal fluctuation via the giant magnetic anisotropy of Os-based dimers. Phys Chem Chem Phys 2018; 20:28169-28175. [DOI: 10.1039/c8cp05407j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Graphene with adsorbed Os-based dimers possesses both giant magnetic anisotropy and a large topological band gap.
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Affiliation(s)
- Kai-Cheng Zhang
- College of Mathematics and Physics
- Bohai University
- Jinzhou 121013
- China
| | - Yong-Feng Li
- School of Science
- Inner Mongolia University of Science and Technology
- Baotou 014010
- China
- Key laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources
| | - Yong Liu
- State Key Laboratory of Metastable Materials Science & Technology and College of Science
- Yanshan University
- Qinhuangdao 066004
- China
| | - Yan Zhu
- Department of Physics
- Nanjing University of Aeronautics and Astronautics
- Nanjing 210016
- China
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17
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Huang H, Xu Y, Wang J, Duan W. Emerging topological states in quasi-two-dimensional materials. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1296] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Huaqing Huang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics; Tsinghua University; Beijing China
- Collaborative Innovation Center of Quantum Matter; Tsinghua University; Beijing China
| | - Yong Xu
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics; Tsinghua University; Beijing China
- Collaborative Innovation Center of Quantum Matter; Tsinghua University; Beijing China
- RIKEN Center for Emergent Matter Science (CEMS); Wako Japan
| | - Jianfeng Wang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics; Tsinghua University; Beijing China
- Collaborative Innovation Center of Quantum Matter; Tsinghua University; Beijing China
| | - Wenhui Duan
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics; Tsinghua University; Beijing China
- Collaborative Innovation Center of Quantum Matter; Tsinghua University; Beijing China
- Institute for Advanced Study; Tsinghua University; Beijing China
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18
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Liu J, Park SY, Garrity KF, Vanderbilt D. Flux States and Topological Phases from Spontaneous Time-Reversal Symmetry Breaking in CrSi(Ge)Te_{3}-Based Systems. PHYSICAL REVIEW LETTERS 2016; 117:257201. [PMID: 28036224 DOI: 10.1103/physrevlett.117.257201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Indexed: 06/06/2023]
Abstract
We study adatom-covered single layers of CrSiTe_{3} and CrGeTe_{3} using first-principles calculations based on hybrid functionals. We find that the insulating ground state of a monolayer of La (Lu) deposited on single-layer CrSiTe_{3} (CrGeTe_{3}) carries spontaneously generated current loops around the Cr sites. These "flux states" induce antiferromagnetically ordered orbital moments on the Cr sites and are also associated with nontrivial topological properties. The calculated Chern numbers for these systems are predicted to be ±1 even in the absence of spin-orbit coupling, with sizable gaps on the order of 100 meV. The flux states and the associated topological phases result from spontaneous time-reversal symmetry breaking due to the presence of nonlocal Coulomb interactions.
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Affiliation(s)
- Jianpeng Liu
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
| | - Se Young Park
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
| | - Kevin F Garrity
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - David Vanderbilt
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
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19
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Huang Z, Liu W, Yue J, Zhou Q, Zhang W, Lu Y, Sui Y, Zhai Y, Chen Q, Dong S, Wang J, Xu Y, Wang B. Enhancing the Spin-Orbit Coupling in Fe 3O 4 Epitaxial Thin Films by Interface Engineering. ACS APPLIED MATERIALS & INTERFACES 2016; 8:27353-27359. [PMID: 27658969 DOI: 10.1021/acsami.6b09478] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By analyzing the in-plane angular dependence of ferromagnetic resonance linewidth, we show that the Gilbert damping constant in ultrathin Fe3O4 epitaxial films on GaAs substrate can be enhanced by thickness reduction and oxygen vacancies in the interface. At the same time, the uniaxial magnetic anisotropy due to the interface effect becomes significant. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the orbital-to-spin moment ratio increases with decreasing film thickness, in full agreement with the increase in the Gilbert damping obtained for these ultrathin single-crystal films. Combined with the first-principle calculations, the results suggest that the bonding with Fe and Ga or As ions and the ionic distortion near the interface, as well as the FeO defects and oxygen vacancies, may increase the spin-orbit coupling in ultrathin Fe3O4 epitaxial films and in turn provide an enhanced damping.
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Affiliation(s)
- Zhaocong Huang
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York, U.K
- School of Electronic Science and Engineering, Southeast University , Nanjing 210096, China
| | - Wenqing Liu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York, U.K
- Department of Electronic Engineering, Royal Holloway, University of London , Surrey, U.K
| | - Jinjin Yue
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Qionghua Zhou
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Wen Zhang
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Yongxiong Lu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York, U.K
| | - Yunxia Sui
- National Laboratory of Solid Microstructures and Center of Modern Analysis, Nanjing University , Nanjing, China
| | - Ya Zhai
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
- National Laboratory of Solid Microstructures and Center of Modern Analysis, Nanjing University , Nanjing, China
| | - Qian Chen
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Shuai Dong
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Jinlan Wang
- Department of Physics, Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University , Nanjing 211189, China
| | - Yongbing Xu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York, U.K
| | - Baoping Wang
- School of Electronic Science and Engineering, Southeast University , Nanjing 210096, China
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20
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Qiao Z, Han Y, Zhang L, Wang K, Deng X, Jiang H, Yang SA, Wang J, Niu Q. Anderson Localization from the Berry-Curvature Interchange in Quantum Anomalous Hall Systems. PHYSICAL REVIEW LETTERS 2016; 117:056802. [PMID: 27517785 DOI: 10.1103/physrevlett.117.056802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 06/06/2023]
Abstract
We theoretically investigate the localization mechanism of the quantum anomalous Hall effect (QAHE) in the presence of spin-flip disorders. We show that the QAHE stays quantized at weak disorders, then enters a Berry-curvature mediated metallic phase at moderate disorders, and finally goes into the Anderson insulating phase at strong disorders. From the phase diagram, we find that at the charge neutrality point although the QAHE is most robust against disorders, the corresponding metallic phase is much easier to be localized into the Anderson insulating phase due to the interchange of Berry curvatures carried, respectively, by the conduction and valence bands. In the end, we provide a phenomenological picture related to the topological charges to better understand the underlying physical origin of the QAHE Anderson localization.
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Affiliation(s)
- Zhenhua Qiao
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Yulei Han
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Lei Zhang
- Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Ke Wang
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xinzhou Deng
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hua Jiang
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
- College of Physics, Soochow University, Suzhou, Jiangsu 215006, China
| | - Shengyuan A Yang
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jian Wang
- Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Qian Niu
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
- ICQM and CICQM, School of Physics, Peking University, Beijing 100871, China
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21
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Qi S, Qiao Z, Deng X, Cubuk ED, Chen H, Zhu W, Kaxiras E, Zhang SB, Xu X, Zhang Z. High-Temperature Quantum Anomalous Hall Effect in n-p Codoped Topological Insulators. PHYSICAL REVIEW LETTERS 2016; 117:056804. [PMID: 27517787 DOI: 10.1103/physrevlett.117.056804] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Indexed: 06/06/2023]
Abstract
The quantum anomalous Hall effect (QAHE) is a fundamental quantum transport phenomenon that manifests as a quantized transverse conductance in response to a longitudinally applied electric field in the absence of an external magnetic field, and it promises to have immense application potential in future dissipationless quantum electronics. Here, we present a novel kinetic pathway to realize the QAHE at high temperatures by n-p codoping of three-dimensional topological insulators. We provide a proof-of-principle numerical demonstration of this approach using vanadium-iodine (V-I) codoped Sb_{2}Te_{3} and demonstrate that, strikingly, even at low concentrations of ∼2% V and ∼1% I, the system exhibits a quantized Hall conductance, the telltale hallmark of QAHE, at temperatures of at least ∼50 K, which is 3 orders of magnitude higher than the typical temperatures at which it has been realized to date. The underlying physical factor enabling this dramatic improvement is tied to the largely preserved intrinsic band gap of the host system upon compensated n-p codoping. The proposed approach is conceptually general and may shed new light in experimental realization of high-temperature QAHE.
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Affiliation(s)
- Shifei Qi
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen, Shanxi 041004, China
| | - Zhenhua Qiao
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xinzhou Deng
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ekin D Cubuk
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Hua Chen
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Wenguang Zhu
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Efthimios Kaxiras
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - S B Zhang
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
| | - Xiaohong Xu
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen, Shanxi 041004, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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22
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Ren Y, Qiao Z, Niu Q. Topological phases in two-dimensional materials: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:066501. [PMID: 27176924 DOI: 10.1088/0034-4885/79/6/066501] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Topological phases with insulating bulk and gapless surface or edge modes have attracted intensive attention because of their fundamental physics implications and potential applications in dissipationless electronics and spintronics. In this review, we mainly focus on recent progress in the engineering of topologically nontrivial phases (such as [Formula: see text] topological insulators, quantum anomalous Hall effects, quantum valley Hall effects etc) in two-dimensional systems, including quantum wells, atomic crystal layers of elements from group III to group VII, and the transition metal compounds.
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Affiliation(s)
- Yafei Ren
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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23
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Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators. Sci Rep 2016; 6:25988. [PMID: 27185665 PMCID: PMC4868970 DOI: 10.1038/srep25988] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/26/2016] [Indexed: 01/28/2023] Open
Abstract
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.
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24
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Dong L, Kim Y, Er D, Rappe AM, Shenoy VB. Two-Dimensional π-Conjugated Covalent-Organic Frameworks as Quantum Anomalous Hall Topological Insulators. PHYSICAL REVIEW LETTERS 2016; 116:096601. [PMID: 26991189 DOI: 10.1103/physrevlett.116.096601] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Indexed: 05/12/2023]
Abstract
The quantum anomalous Hall (QAH) insulator is a novel topological state of matter characterized by a nonzero quantized Hall conductivity without an external magnetic field. Using first-principles calculations, we predict the QAH state in monolayers of covalent-organic frameworks based on the newly synthesized X_{3}(C_{18}H_{12}N_{6})_{2} structure where X represents 5d transition metal elements Ta, Re, and Ir. The π conjugation between X d_{xz} and d_{yz} orbitals, mediated by N p_{z} and C p_{z} orbitals, gives rise to a massive Dirac spectrum in momentum space with a band gap of up to 24 meV due to strong spin-orbit coupling. We show that the QAH state can appear by chemically engineering the exchange field and the Fermi level in the monolayer structure, resulting in nonzero Chern numbers. Our results suggest a reliable pathway toward the realization of a QAH phase at temperatures between 100 K and room temperature in covalent-organic frameworks.
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Affiliation(s)
- Liang Dong
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Youngkuk Kim
- The Makineni Theoretical Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Dequan Er
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Andrew M Rappe
- The Makineni Theoretical Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Vivek B Shenoy
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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25
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Shen HZ, Qin M, Shao XQ, Yi XX. General response formula and application to topological insulator in quantum open system. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:052122. [PMID: 26651662 DOI: 10.1103/physreve.92.052122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 06/05/2023]
Abstract
It is well-known that the quantum linear response theory is based on the first-order perturbation theory for a system in thermal equilibrium. Hence, this theory breaks down when the system is in a steady state far from thermal equilibrium and the response up to higher order in perturbation is not negligible. In this paper, we develop a nonlinear response theory for such quantum open system. We first formulate this theory in terms of general susceptibility, after which we apply it to the derivation of Hall conductance for open system at finite temperature. As an example, the Hall conductance of the two-band model is derived. Then we calculate the Hall conductance for a two-dimensional ferromagnetic electron gas and a two-dimensional lattice model. The calculations show that the transition points of topological phase are robust against the environment. Our results provide a promising platform for the coherent manipulation of the nonlinear response in quantum open system, which has potential applications for quantum information processing and statistical physics.
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Affiliation(s)
- H Z Shen
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
- School of Physics and Optoelectronic Technology Dalian University of Technology, Dalian 116024, China
| | - M Qin
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
- School of Physics and Optoelectronic Technology Dalian University of Technology, Dalian 116024, China
| | - X Q Shao
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
| | - X X Yi
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
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26
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Lachman EO, Young AF, Richardella A, Cuppens J, Naren HR, Anahory Y, Meltzer AY, Kandala A, Kempinger S, Myasoedov Y, Huber ME, Samarth N, Zeldov E. Visualization of superparamagnetic dynamics in magnetic topological insulators. SCIENCE ADVANCES 2015; 1:e1500740. [PMID: 26601138 PMCID: PMC4640587 DOI: 10.1126/sciadv.1500740] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/26/2015] [Indexed: 05/23/2023]
Abstract
Quantized Hall conductance is a generic feature of two-dimensional electronic systems with broken time reversal symmetry. In the quantum anomalous Hall state recently discovered in magnetic topological insulators, time reversal symmetry is believed to be broken by long-range ferromagnetic order, with quantized resistance observed even at zero external magnetic field. We use scanning nanoSQUID (nano-superconducting quantum interference device) magnetic imaging to provide a direct visualization of the dynamics of the quantum phase transition between the two anomalous Hall plateaus in a Cr-doped (Bi,Sb)2Te3 thin film. Contrary to naive expectations based on macroscopic magnetometry, our measurements reveal a superparamagnetic state formed by weakly interacting magnetic domains with a characteristic size of a few tens of nanometers. The magnetic phase transition occurs through random reversals of these local moments, which drive the electronic Hall plateau transition. Surprisingly, we find that the electronic system can, in turn, drive the dynamics of the magnetic system, revealing a subtle interplay between the two coupled quantum phase transitions.
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Affiliation(s)
- Ella O. Lachman
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Andrea F. Young
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106–9530, USA
| | - Anthony Richardella
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Jo Cuppens
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - H. R. Naren
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yonathan Anahory
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alexander Y. Meltzer
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Abhinav Kandala
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Susan Kempinger
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Yuri Myasoedov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Martin E. Huber
- Department of Physics, University of Colorado Denver, Denver, CO 80217, USA
| | - Nitin Samarth
- Department of Physics, Pennsylvania State University, University Park, PA 16802, USA
| | - Eli Zeldov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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27
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High-Efficiency Cooper-Pair Splitter in Quantum Anomalous Hall Insulator Proximity-Coupled with Superconductor. Sci Rep 2015; 5:14892. [PMID: 26450824 PMCID: PMC4598733 DOI: 10.1038/srep14892] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/09/2015] [Indexed: 12/02/2022] Open
Abstract
The quantum entanglement between two qubits is crucial for applications in the quantum communication. After the entanglement of photons was experimentally realized, much effort has been taken to exploit the entangled electrons in solid-state systems. Here, we propose a Cooper-pair splitter, which can generate spatially-separated but entangled electrons, in a quantum anomalous Hall insulator proximity-coupled with a superconductor. After coupling with a superconductor, the chiral edge states of the quantum anomalous Hall insulator can still survive, making the backscattering impossible. Thus, the local Andreev reflection becomes vanishing, while the crossed Andreev reflection becomes dominant in the scattering process. This indicates that our device can serve as an extremely high-efficiency Cooper-pair splitter. Furthermore, because of the chiral characteristic, our Cooper-pair splitter is robust against disorders and can work in a wide range of system parameters. Particularly, it can still function even if the system length exceeds the superconducting coherence length.
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28
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Zhang J, Zhao B, Yao Y, Yang Z. Quantum Anomalous Hall Effect in Graphene-based Heterostructure. Sci Rep 2015; 5:10629. [PMID: 26024508 PMCID: PMC4448525 DOI: 10.1038/srep10629] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/22/2015] [Indexed: 11/24/2022] Open
Abstract
Quantum anomalous Hall (QAH) effect, with potential applications in low-power-consumption electronics, is predicted in the heterostructure of graphene on the (001) surface of a real antiferromagnetic insulator RbMnCl3, based on density-functional theory and Wannier function methods. Due to the interactions from the substrate, a much large exchange field (about 280 meV) and an enhanced Rashba spin-orbit coupling are induced in graphene, leading to a topologically nontrivial QAH gap opened in the system. The avenues of enhancing the nontrivial gap are also proposed, from which nearly a gap one order large is achieved. Our work demonstrates that this graphene-based heterostructure is an appropriate candidate to be employed to experimentally observe the QAH effect and explore the promising applications.
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Affiliation(s)
- Jiayong Zhang
- State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) &Department of Physics, Fudan University, Shanghai 200433, China
| | - Bao Zhao
- State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) &Department of Physics, Fudan University, Shanghai 200433, China
| | - Yugui Yao
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Zhongqin Yang
- 1] State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) &Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai, 200433, China
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29
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Chang CZ, Zhao W, Kim DY, Zhang H, Assaf BA, Heiman D, Zhang SC, Liu C, Chan MHW, Moodera JS. High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator. NATURE MATERIALS 2015; 14:473-7. [PMID: 25730394 DOI: 10.1038/nmat4204] [Citation(s) in RCA: 250] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 12/19/2014] [Indexed: 05/13/2023]
Abstract
The discovery of the quantum Hall (QH) effect led to the realization of a topological electronic state with dissipationless currents circulating in one direction along the edge of a two-dimensional electron layer under a strong magnetic field. The quantum anomalous Hall (QAH) effect shares a similar physical phenomenon to that of the QH effect, whereas its physical origin relies on the intrinsic spin-orbit coupling and ferromagnetism. Here, we report the experimental observation of the QAH state in V-doped (Bi,Sb)2Te3 films with the zero-field longitudinal resistance down to 0.00013 ± 0.00007h/e(2) (~3.35 ± 1.76 Ω), Hall conductance reaching 0.9998 ± 0.0006e(2)/h and the Hall angle becoming as high as 89.993° ± 0.004° at T = 25 mK. A further advantage of this system comes from the fact that it is a hard ferromagnet with a large coercive field (Hc > 1.0 T) and a relative high Curie temperature. This realization of a robust QAH state in hard ferromagnetic topological insulators (FMTIs) is a major step towards dissipationless electronic applications in the absence of external fields.
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Affiliation(s)
- Cui-Zu Chang
- Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Weiwei Zhao
- The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Duk Y Kim
- The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Haijun Zhang
- Department of Physics, Stanford University, Stanford, California 94305-4045, USA
| | - Badih A Assaf
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Don Heiman
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Shou-Cheng Zhang
- Department of Physics, Stanford University, Stanford, California 94305-4045, USA
| | - Chaoxing Liu
- The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Moses H W Chan
- The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA
| | - Jagadeesh S Moodera
- 1] Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Hu J, Zhu Z, Wu R. Chern half metals: a new class of topological materials to realize the quantum anomalous Hall effect. NANO LETTERS 2015; 15:2074-2078. [PMID: 25689149 DOI: 10.1021/nl504981g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
New topological insulators that demonstrate the quantum anomalous Hall effect (QAHE) are a cutting-edge research topic in condensed matter physics and materials science. So far, the QAHE has been observed only in Cr-doped (Bi,Sb)2Te3 at extremely low temperature. Therefore, it is important to find new materials with large topological band gap and high thermal stability for the realization of the QAHE. On the basis of first-principles and tight-binding model calculations, we discovered a new class of topological phase, Chern half metal, which manifests the QAHE in one spin channel while is metallic in the other spin channel, in Co or Rh deposited graphene. The QAHE is robust in these sytems for the adatom coverage ranging from 2% to 6%. Meanwhile, these systems have large perpendicular magnetic anisotropy energies of 5.3 and 11.5 meV, necessary for the observation of the QAHE at reasonably high temperature.
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Affiliation(s)
- Jun Hu
- College of Physics, Optoelectronics and Energy, Soochow University , Suzhou, Jiangsu 215006, China
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Abstract
Stable FM coupling gives rise to a quantum anomalous Hall state at Dirac points in nitrogen-doped graphene kagome nanomesh.
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Affiliation(s)
- Xiaoming Zhang
- School of Physics and State Key Laboratory of Crystal Materials
- Shandong University
- Jinan 250100
- China
| | - Mingwen Zhao
- School of Physics and State Key Laboratory of Crystal Materials
- Shandong University
- Jinan 250100
- China
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Wu SC, Shan G, Yan B. Prediction of near-room-temperature quantum anomalous Hall effect on honeycomb materials. PHYSICAL REVIEW LETTERS 2014; 113:256401. [PMID: 25554896 DOI: 10.1103/physrevlett.113.256401] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Indexed: 05/15/2023]
Abstract
Recently, the long-sough quantum anomalous Hall effect was realized in a magnetic topological insulator. However, the requirement of an extremely low temperature (approximately 30 mK) hinders realistic applications. Based on ab initio band structure calculations, we propose a quantum anomalous Hall platform with a large energy gap of 0.34 and 0.06 eV on honeycomb lattices comprised of Sn and Ge, respectively. The ferromagnetic (FM) order forms in one sublattice of the honeycomb structure by controlling the surface functionalization rather than dilute magnetic doping, which is expected to be visualized by spin polarized STM in experiment. Strong coupling between the inherent quantum spin Hall state and ferromagnetism results in considerable exchange splitting and, consequently, an FM insulator with a large energy gap. The estimated mean-field Curie temperature is 243 and 509 K for Sn and Ge lattices, respectively. The large energy gap and high Curie temperature indicate the feasibility of the quantum anomalous Hall effect in the near-room-temperature and even room-temperature regions.
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Affiliation(s)
- Shu-Chun Wu
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Guangcun Shan
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Binghai Yan
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany and Max Planck Institute for Physics of Complex Systems, D-01187 Dresden, Germany
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Epitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface. Proc Natl Acad Sci U S A 2014; 111:14378-81. [PMID: 25246584 DOI: 10.1073/pnas.1409701111] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Formation of topological quantum phase on a conventional semiconductor surface is of both scientific and technological interest. Here, we demonstrate epitaxial growth of 2D topological insulator, i.e., quantum spin Hall state, on Si(111) surface with a large energy gap, based on first-principles calculations. We show that the Si(111) surface functionalized with one-third monolayer of halogen atoms [Si(111)-√3 x √3 -X (X = Cl, Br, I)] exhibiting a trigonal superstructure provides an ideal template for epitaxial growth of heavy metals, such as Bi, which self-assemble into a hexagonal lattice with high kinetic and thermodynamic stability. Most remarkably, the Bi overlayer is atomically bonded to but electronically decoupled from the underlying Si substrate, exhibiting isolated quantum spin Hall state with an energy gap as large as ∼ 0.8 eV. This surprising phenomenon originates from an intriguing substrate-orbital-filtering effect, which critically selects the orbital composition around the Fermi level, leading to different topological phases. In particular, the substrate-orbital-filtering effect converts the otherwise topologically trivial freestanding Bi lattice into a nontrivial phase; and the reverse is true for Au lattice. The underlying physical mechanism is generally applicable, opening a new and exciting avenue for exploration of large-gap topological surface/interface states.
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Qiao Z, Ren W, Chen H, Bellaiche L, Zhang Z, Macdonald AH, Niu Q. Quantum anomalous Hall effect in graphene proximity coupled to an antiferromagnetic insulator. PHYSICAL REVIEW LETTERS 2014; 112:116404. [PMID: 24702394 DOI: 10.1103/physrevlett.112.116404] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Indexed: 05/07/2023]
Abstract
We propose realizing the quantum anomalous Hall effect by proximity coupling graphene to an antiferromagnetic insulator that provides both broken time-reversal symmetry and spin-orbit coupling. We illustrate our idea by performing ab initio calculations for graphene adsorbed on the (111) surface of BiFeO3. In this case, we find that the proximity-induced exchange field in graphene is about 70 meV, and that a topologically nontrivial band gap is opened by Rashba spin-orbit coupling. The size of the gap depends on the separation between the graphene and the thin film substrate, which can be tuned experimentally by applying external pressure.
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Affiliation(s)
- Zhenhua Qiao
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and ICQD, Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Wei Ren
- Department of Physics, Shanghai University, Shanghai 200444, China and Department of Physics, The University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Hua Chen
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - L Bellaiche
- Department of Physics, The University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Zhenyu Zhang
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - A H Macdonald
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Qian Niu
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA and International Center for Quantum Materials, Peking University, Beijing 100871, China
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