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General electronic structure calculation method for twisted systems

Physical Review B 2025年第7期111卷 075434-075434页

作者： Junxi Yu Shifeng Qian Cheng-Cheng Liu Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) and Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials Department of Physics Anhui Normal University Anhui Wuhu 241000 China

In recent years, two-dimensional twisted systems have gained increasing attention. However, calculating the electronic structures in twisted materials has remained a challenge. To address this, we have developed a general computational methodology that can generate twisted geometries starting from a monolayer structure and obtain a precisely relaxed twisted structure through a machine learning-based method. Then, the electronic structure properties of the twisted material are calculated using the tight-binding (TB) and continuum model methods; thus, the entire process requires minimal computational resources. We introduce the theoretical methods for generating twisted structures and computing their electronic properties, and further provide calculations and brief analyses of the electronic structure properties for several typical two-dimensional materials with different characteristics. This paper serves as a solid foundation for researchers interested in studying twisted systems.

关键词： Electronic properties

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Type-II topological metals

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Frontiers of physics 2020年第4期15卷 101-112页

作者： Si Li Zhi-Ming Yu Yugui Yao Shengyuan A.Yang Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innouation Center for Quantum Efects and ApplicationsHunan Norrmal UniversityChangsha 410081China Research Laboratory for Quantum Materials Singapore University of Technology and DesignSingapore 487372Singapore Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Lab of Nanophotonics&Utrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Topological metals(TMs)are a kind of special metallic materials,which feature nontrivial band Cross-ings near the Fermi energy,giving rise to peculiar quasiparticle *** can be classified based on the characteristics of these band *** example,according to the dimensionality of the crossing,TMs can be classifed into nodal-point,nodal-line,and nodal-surface *** important property is the type of *** to degree of the tilt of the local dispersion around the crossing,we have typeI and type-II *** leads to significant distinctions in the physical properties of the materials,owing to their contrasting Fermi surface *** this article,we briefly review the recent advances in this research direction,focusing on the concepts,the physical properties,and the material realizations of the type-Il nodal-point and nodal-line TMs.

关键词： type-II nodal point nodal line topological metals

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Band gap opening induced by vanishing interlayer interaction in intercalated 1T′−MoTe2

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Physical Review B 2025年第19期111卷 195119-195119页

作者： Mingshu Tan Helin Mei Zhiyu Liao Xueying Ma Keyi Li Wei Ren Shaoshuai Hou Jianting Ji Feng Jin Zhiming Yu Junwei Zhang Xianggang Qiu Anmin Zhang Qingming Zhang School of Physical Science and Technology Key Laboratory of Quantum Theory and Applications of MoE Lanzhou University Lanzhou 73000China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) and School of Physics Beijing Institute of Technology Beijing 100081 China School of Materials and Energy Electron Microscopy Centre of Lanzhou University Lanzhou 730000 China

A substantial energy gap is essential for quantum spin Hall (QSH) insulators in devices and fundamental research. Monolayer 1T′−MoTe2 is recognized as a promising candidate, featuring a potentially large energy gap. However, despite extensive efforts including molecular beam epitaxy growth, mechanical exfoliation, and chemical vapor deposition techniques, achieving stable 1T′−MoTe2 with a well-defined energy gap has proven elusive. Here, we successfully open a band gap of approximately 70 meV in bulk 1T′−MoTe2 by reducing the interlayer interaction through the intercalation of organic cations HMIM+. Both resistivity measurements and infrared spectroscopy confirm distinct semiconducting behaviors. Band structure calculations show that the gap emerges from the absence of interlayer coupling, and that the intercalated 1T′−MoTe2 is topologically nontrivial with Z2=1. This work not only demonstrates a bulk 1T′−MoTe2 possible QSH insulator with a sizable gap, but also provides a different approach to realizing clean, stable platforms for exploring the QSH effect and designing low-power quantum electronic and spintronic devices.

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Type-Ⅱ topological metals

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物理学前沿 2020年第4期15卷 98-109页

作者： Si Li Zhi-Ming Yu Yugui Yao Shengyuan A.Yang Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal University Changsha 410081 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems and School of Physics Beijing Institute of Technology Beijing 100081 China

Topological metals (TMs) are a kind of special metallic materials,which feature nontrivial band crossings near the Fermi energy,giving rise to peculiar quasiparticle *** can be classified based on the characteristics of these band *** example,according to the dimensionality of the crossing,TMs can be classified into nodal-point,nodal-line,and nodal-surface *** important property is the type of *** to degree of the tilt of the local dispersion around the crossing,we have type-Ⅰ and type-Ⅱ *** leads to significant distinctions in the physical properties of the materials,owing to their contrasting Fermi surface *** this article,we briefly review the recent advances in this research direction,focusing on the concepts,the physical properties,and the material realizations of the type-Ⅱ nodal-point and nodal-line TMs.

关键词： type-Ⅱ nodal point nodal line topological metals

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Engineering strong spin-frustration at the surface of three-dimensional graphene

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Science Bulletin 2024年第18期69卷 2816-2819页

作者： Wenjing Li Ken Chen Menglei Li Huiying Gao Jize Zhao Fawei Zheng Wenhui Duan Center for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing 100081China Beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing 100081China School of Physical Science and Technology Key Laboratory of Quantum Theory and Applications of MOELanzhou UniversityLanzhou 730000China Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu ProvinceLanzhou UniversityLanzhou 730000China Department of Physics Capital Normal UniversityBeijing 100048China State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Institute for Advanced Study Tsinghua UniversityBeijing 100084China Frontier Science Center for Quantum Information Beijing 100084China Beijing Academy of Quantum Information Sciences Beijing 100193China

Since the first successful fabrication in 2004[1],graphene has received tremendous attention due to its extremely simple atomic structure and alluring physical *** example,its massless low energy excitations have a linear dispersion and thus its transport property is governed by Dirac equation instead of Schr?dinger *** special electronic structures suppress the intra-valley and inter-valley backscatterings,leading to the half-integer and fractional quantum Hall effect[2]under magnetic field and the relativistic quantum tunneling described by the Klein paradox[3].

关键词： properties equation quantum

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Introducing the quantum Research Kernels: Lessons from Classical Parallel Computing

arXiv

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arXiv 2022年

作者： Matsuura, A.Y. Mattson, Timothy G. Applications and Quantum Architecture Lab Intel Corp HillsboroOR United States Parallel Computing Lab Intel Corp. IlwacoWA United States

quantum computing represents a paradigm shift for computation requiring an entirely new computer architecture. However, there is much that can be learned from traditional classical computer engineering. In this paper, we describe the Parallel Research Kernels (PRK), a tool that was very useful for designing classical parallel computing systems. The PRK are simple kernels written to expose bottlenecks that limit classical parallel computing performance. We hypothesize that an analogous tool for quantum computing, quantum Research Kernels (QRK), may similarly aid the codesign of software and hardware for quantum computing systems, and we give a few examples of representative QRKs. Copyright © 2022, The Authors. All rights reserved.

关键词： Hardware-software codesign

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Anomalous spatial shifts in interface electronic reflection beyond the linear approximation

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Physical Review B 2023年第7期108卷 075149-075149页

作者： Runze Li Chaoxi Cui Xinxing Zhou Zhi-Ming Yu Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applications School of Physics and Electronics Hunan Normal University Changsha 410081 China

Recently, the electronic analogy of the anomalous spatial shift, including Goos-Hänchen and Imbert-Fedorov effects, has been attracting widespread interest. Current research on the anomalous spatial shift in interface electronic reflection is based on the paradigm of linear approximation, under which the center position of the incident and reflected beams are obtained by expanding the phases of relevant basis states and scattering amplitudes to the first order of incident momentum. However, in a class of normal cases, the linear approximation leads to divergent spatial shifts in reflection for certain incident angles, even though the corresponding reflection possibility is finite. In this paper, we show that these nonphysical results are caused by an abrupt change in the number of the propagating states at critical parameters, and can be resolved by calculating the center positions of the scattering beams beyond the linear approximation. Moreover, we find that the beam width has an important influence on the spatial shift near the critical angles. We demonstrate our idea via concrete calculations of Goos-Hänchen and Imbert-Fedorov shift on two representative models. These results provide a deeper understanding of the anomalous spatial shift in calculations.

关键词： Andreev reflection Electronic structure Unconventional superconductors Weyl semimetal

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Multiple magnetism-controlled topological states in EuAgAs

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Physical Review B 2021年第16期104卷 165424-165424页

作者： Yahui Jin Xu-Tao Zeng Xiaolong Feng Xin Du Weikang Wu Xian-Lei Sheng Zhi-Ming Yu Ziming Zhu Shengyuan A. Yang Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China School of Physics and Key Laboratory of Micro-nano Measurement-Manipulation and Physics Beihang University Beijing 100191 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems and School of Physics Beijing Institute of Technology Beijing 100081 China

The interplay between magnetism and band topology is a focus of current research on magnetic topological systems. Based on first-principle calculations and symmetry analysis, we reveal that multiple intriguing topological states can be realized in a single system EuAgAs, controlled by the magnetic ordering. The material is a Dirac semimetal in the paramagnetic state, with a pair of accidental Dirac points. Under different magnetic configurations, the Dirac points can evolve into magnetic triply degenerate points, magnetic linear and double Weyl points, or being gapped out and making the system a topological mirror semimetal characterized by mirror Chern numbers. The change in bulk topology is also manifested in the surface states, including the surface Fermi arcs and surface Dirac cones. In addition, the antiferromagnetic states also feature a nontrivial Z4 index, implying a higher order topology. These results deepen our understanding of magnetic topological states and provide different perspectives for spintronic applications.

关键词： Antiferromagnetism Electronic structure First-principles calculations Topological materials

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First-principles study of bulk and two-dimensional structures of the AMnBi family of materials (A=K,Rb,Cs)

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Physical Review B 2020年第3期102卷 035444-035444页

作者： Ziming Zhu Chunyan Liao Si Li Xiaoming Zhang Weikang Wu Zhi-Ming Yu Rui Yu Wei Zhang Shengyuan A. Yang Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore School of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems and School of Physics Beijing Institute of Technology Beijing 100081 China School of Physics and Technology Wuhan University Wuhan 430072 China Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and Energy Fujian Normal University Fuzhou 350117 China School of Physics and Technology Center for Quantum Transport and Thermal Energy Science Nanjing Normal University Nanjing 210023 China

Magnetic materials with high mobilities are intriguing subjects of research from both fundamental and application perspectives. Based on first-principle calculations, we investigate the physical properties of the already synthesized AMnBi (A=K, Rb, Cs) family materials. We show that these materials are antiferromagnetic (AFM), with Néel temperatures above 300 K. They contain AFM ordered Mn layers, while the interlayer coupling changes from ferromagnetic (FM) for KMnBi to AFM for RbMnBi and CsMnBi. We find that these materials are narrow gap semiconductors. Owing to the small effective mass, the electron carrier mobility can be very high, reaching up to 105cm2/(Vs) for KMnBi. In contrast, the hole mobility is much suppressed, typically lower by two orders of magnitude. We further study their two-dimensional (2D) single layer structures, which are found to be AFM with fairly high mobility ∼103cm2/(Vs). Their Néel temperatures can still reach room temperature. Interesting, we find that the magnetic phase transition is also accompanied by a metal-insulator phase transition, with the paramagnetic metal phase possessing a pair of nonsymmorphic-symmetry-protected 2D spin-orbit Dirac points. Furthermore, the magnetism can be effectively controlled by the applied strain. When the magnetic ordering is turned into FM, the system can become a quantum anomalous Hall insulator with gapless chiral edge states.

关键词： Edge states First-principles calculations Magnetic phase transitions Spin-orbit coupling Topological materials Transport phenomena

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三维石墨烯表面的强自旋阻挫（英文）

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Science Bulletin 2024年第18期 2816-2819页

作者：李文静陈垦李梦蕾高慧颖赵继泽郑法伟段文晖 Center for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE)School of PhysicsBeijing Institute of Technology Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of Technology School of Physical Science and Technology Key Laboratory of Quantum Theory and Applications of MOELanzhou University Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu ProvinceLanzhou University Department of Physics Capital Normal University State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua University Institute for Advanced Study Tsinghua University Frontier Science Center for Quantum Information Beijing Academy of Quantum Information Sciences

Since the first successful fabrication in 2004 [1], graphene has received tremendous attention due to its extremely simple atomic structure and alluring physical properties. For example, its massless low energy excitations have a linear dispersion and thus its transport property is governed by Dirac equation instead of Schr?dinger equation. These special electronic structures suppress the intra-valley and inter-valley backscatterings, leading to the half-integer and fractional quantum Hall effect [2] under magnetic field and the relativistic quantum tunneling described by the Klein paradox [3].

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