检索结果-内蒙古大学图书馆

Intrinsic quantum anomalous Hall phase induced by proximity in the van der Waals heterostructure germanene/Cr2Ge2Te6

引用

Physical Review B 2020年第16期101卷 161108(R)-161108(R)页

作者： Runling Zou Fangyang Zhan Baobing Zheng Xiaozhi Wu Jing Fan Rui Wang Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 People's Republic of China College of Physics and Optoelectronic Technology Nonlinear Research Institute Baoji University of Arts and Sciences Baoji 721016 People's Republic of China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China Center for Quantum Materials and Devices Chongqing University Chongqing 400044 People's Republic of China

A van der Waals heterostructure combined with intrinsic magnetism and topological orders have recently paved attractive avenues to realize quantum anomalous Hall effects. In this work, using first-principles calculations and effective model analysis, we propose that the robust quantum anomalous Hall states with sizable band gaps emerge in the van der Waals heterostructure of germanene/Cr2Ge2Te6. This heterostructure possesses high thermodynamic stability, thus facilitating its experimental fabrication. Furthermore, we uncover that the proximity effect enhances the coupling between the germanene and Cr2Ge2Te6 layers, inducing the nontrivial band gaps in a wide range from 29 to 72 meV. The chiral edge states inside the band gap, leading to Hall conductance quantized to −e2/h, are clearly visible. These findings provide an ideal candidate to detect the quantum anomalous Hall states and realize further applications to nontrivial quantum transport at a high temperature.

关键词： Chern insulators First-principles calculations Spin-orbit coupling Topological materials Topological phases of matter wannier function methods k dot p method

来源：评论

学校读者我要写书评

暂无评论

Supercell wannier functions and a faithful low-energy model for Bernal bilayer graphene

引用

Physical Review B 2024年第20期110卷 L201113-L201113页

作者： Ammon Fischer Lennart Klebl Dante M. Kennes Tim O. Wehling Institute for Theory of Statistical Physics RWTH Aachen University and JARA Fundamentals of Future Information Technology 52062 Aachen Germany I. Institute for Theoretical Physics Universität Hamburg Notkestraße 9-11 22607 Hamburg Germany Max Planck Institute for the Structure and Dynamics of Matter Center for Free Electron Laser Science 22761 Hamburg Germany The Hamburg Centre for Ultrafast Imaging 22761 Hamburg Germany

We derive a minimal low-energy model for Bernal bilayer graphene and related rhombohedral graphene multilayers at low electronic densities by constructing wannier orbitals defined in real-space supercells of the original primitive cell. Starting from an ab initio electronic structure theory comprising the atomic carbon pz orbitals, momentum locality of the Fermi surface pockets around K,K′ is circumvented by back folding the π bands to the concomitant mini-Brillouin zone of the supercell, reminiscent of their (twisted) moiré counterparts. The supercell wannier functions reproduce the spectral weight and Berry curvature of the microscopic model and offer an intuitive real-space picture of the emergent physics at low electronic densities being shaped by flavor-polarized wave packets with mesoscopic extent. By projecting an orbital-resolved, dual-gated Coulomb interaction to the effective wannier basis, we find that the low-energy physics of Bernal bilayer graphene is governed by weak electron-electron interactions. Our study bridges between existing continuum theories and ab initio studies of small Fermi pocket systems such as rhombohedral graphene stacks by providing a symmetric lattice description of their low-energy physics.

关键词： Electronic structure Bilayer graphene Graphene Tight-binding model wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Nodal line fermions in magnetic oxides

引用

Physical Review B 2018年第24期97卷 241111(R)-241111(R)页

作者： R. Wang J. Z. Zhao Y. J. Jin Y. P. Du Y. X. Zhao H. Xu S. Y. Tong Department of Physics South University of Science and Technology of China Shenzhen 518055 People's Republic of China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 People's Republic of China Department of Applied Physics Nanjing University of Science and Technology Nanjing Jiangsu 210094 People's Republic of China National Laboratory of Solid State Microstructures and Department of Physics Nanjing University Nanjing 210093 People's Republic of China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 People's Republic of China School of Science and Engineering The Chinese University of Hong Kong Shenzhen 518172 People's Republic of China

Using symmetry considerations, we show that nodal rings in a certain class of magnetic oxides are guaranteed to remain gapless in the presence of spin-orbital coupling (SOC). The condition is that the compound must possess a mirror plane perpendicular to its intrinsic magnetic moment. We also show by first-principles calculations that a number of widely used compounds with a cubic phase, such as Fe3O4, CrO2, Li2VO4, Li2TiO4, and Cu2TiO4, belonging to the symmorphic magnetic group D4h(C4h), possess nodal rings with this guaranteed feature. Furthermore, we investigate drumhead surface states of these compounds bounded by a semi-infinite (001) surface. The drumhead surface states in some of our proposed materials (e.g., CrO2), located near the Fermi level, are easily detectable and guaranteed to be intact in the presence of SOC. The findings are important to applications of topological materials to quantum transport. This work also demonstrates the use of symmetry considerations as a powerful pathway for discovering stable node-line fermions and nontrivial surface states in the presence of SOC.

关键词： Ferrimagnetism Ferromagnetism Node-line semimetals Topological materials First-principles calculations wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Superconductivity in sodalite-like yttrium hydride clathrates

引用

Physical Review B 2019年第22期99卷 220502(R)-220502(R)页

作者： Christoph Heil Simone di Cataldo Giovanni B. Bachelet Lilia Boeri Institute of Theoretical and Computational Physics Graz University of Technology NAWI Graz 8010 Graz Austria Dipartimento di Fisica Sapienza Università di Roma 00185 Roma Italy

Motivated by the discovery of near-room-temperature superconductivity in the sodalite-like clathrate hydride LaH10, we report ab initio calculations of the superconducting properties of two closely related hydrides YH6 and YH10 for which an even higher Tc has been predicted. Using fully anisotropic Migdal-Eliashberg theory with Coulomb corrections, we find almost isotropic superconducting gaps, resulting from a uniform distribution of the coupling over states of both Y and H sublattices. The Coulomb screening is rather weak, resulting in a Morel-Anderson pseudopotential μ*=0.11, at odds with claims of unusually large μ* in lanthanum hydrides. The corresponding critical temperatures at 300 GPa exceed room temperature (Tc=290 and 310 K for YH6 and YH10), in agreement with a previous isotropic-gap calculation. We estimate anharmonic effects to be weak. The different response of these two compounds to external pressure along with a comparison to low-Tc superconducting YH3 may inspire strategies to improve the superconducting properties of this class of hydrides.

关键词： Crystal structure Electron-phonon coupling Electronic structure Impurities in superconductors Pressure effects Superconducting phase transition Clathrates High-temperature superconductors Hydrides Density functional calculations Eliashberg theory methods in superconductivity wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Photoinduced Floquet mixed-Weyl semimetallic phase in a carbon allotrope

引用

Physical Review B 2020年第20期102卷 201105(R)-201105(R)页

作者： Tingwei Deng Baobing Zheng Fangyang Zhan Jing Fan Xiaozhi Wu Rui Wang Institute for Structure and Function and Department of Physics Chongqing University Chongqing 400044 People's Republic of China College of Physics and Optoelectronic Technology Nonlinear Research Institute Baoji University of Arts and Sciences Baoji 721016 People's Republic of China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China Center for Quantum Materials and Devices Chongqing University Chongqing 400044 People's Republic of China

The interplay between light and matter attracts tremendous interest for exploring novel topological quantum states and their phase transitions. Here we show by first-principles calculations and the Floquet theorem that a carbon allotrope body-centered tetragonal C16 (bct−C16), a typical nodal-line semimetal, exhibits exotic photoinduced Floquet mixed-Weyl semimetallic features. Under the irradiation of a linearly polarized light, bct−C16 undergoes a topological phase transition from a nodal-line semimetal to a Weyl semimetal with two pairs of tunable Weyl points. With increasing the light intensity, left-handed Weyl points evolve from type I into type II while right-handed ones are always preserved to be type I, giving rise to light-induced unconventional Weyl pairs composed of distinct types of Weyl points. Importantly, a special Weyl pair formed by type-I and type-III Weyl points is present at the critical transition point. The photon-dressed Fermi arcs connecting the projections of two different types of Weyl points are clearly visible, further revealing their unique topological features. Our work not only realizes promising unconventional Weyl pairs but also paves a reliable avenue for investigating light-induced topological phase transitions.

关键词： Photoinduced effect Topological materials Carbon-based materials Weyl semimetal Bloch-Floquet theorem Density functional theory Tight-binding model wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Obstructed atomic insulators with robust corner modes

引用

Physical Review B 2023年第10期108卷 L100101-L100101页

作者： Da-Shuai Ma Kejun Yu Xiao-Ping Li Xiaoyuan Zhou Rui Wang Institute for Structure and Function & Department of Physics & Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing 400044 People's Republic of China Center of Quantum materials and devices Chongqing University Chongqing 400044 People's Republic of China 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 and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China

Higher-order topological insulators (HOTIs), that are classified as obstructed atomic insulators (OAIs) in the topological quantum chemistry (TQC) theory, attract great interest owning to the lower-dimensional topological boundary states. However, the boundary states in HOTIs reported so far are often fragile, manifested as strongly depending on crystalline symmetries and cleavage terminations in the disk or cylinder geometry. Here, using the TQC theory, we propose an intuitive strategy to establish the connection between the obstructed wannier charge centers of OAIs and the emergence of robust corner states in two-dimensional systems. Based on first-principles calculations and real space invariant theory, we extend the concept of OAIs to phonon systems and thereby predict that the robust corner states can be realized in the phonon spectra of MX3 (M = Bi, Sb, As, Sc, Y; X = I, Br, Cl) monolayers. The phonon corner modes in different shapes of nanodisks are investigated, and their robustness facilitates the detection in experiments and further applications. This work suggests a promising avenue to explore more attractive features of higher-order band topology beyond the existing paradigm.

关键词： Edge states First-principles calculations Phonons Topological materials Topological phases of matter 2-dimensional systems Topological insulators High-throughput calculations wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Tuning corner states in proximitized second-order topological insulators with bulk-boundary obstruction

引用

Physical Review B 2023年第16期108卷 L161110-L161110页

作者： Yang Xue Tong Zhou Wei Xu Bao Zhao Igor Žutić Zhongqin Yang Department of Physics East China University of Science and Technology Shanghai 200237 China Eastern Institute for Advanced Study Eastern Institute of Technology Ningbo Zhejiang 315200 China Department of Physics University at Buffalo State University of New York Buffalo New York 14260 USA State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) and Department of Physics Fudan University Shanghai 200433 China Shandong Key Laboratory of Optical Communication Science and Technology School of Physics Science and Information Technology Liaocheng University Liaocheng 252059 China Shanghai Qi Zhi Institute Shanghai 200030 China

Second-order topological insulators (SOTIs) support topological states beyond the usual bulk-boundary correspondence and provide important connections between quantum chemistry and topology. A hallmark of the two-dimensional (2D) SOTIs is the emergence of corner states, which usually arise from the topologically nontrivial obstructed states in the bulk. In contrast, we reveal a very different scenario where even trivial obstructed bulk states can induce corner states due to their open boundaries. Remarkably, we show that these two types of corner states can coexist in a single system and predict, from first-principles calculations, that the monolayer C2N is a promising candidate for their observation. To overcome the limitation in manipulating corner states, we demonstrate it can be accomplished using a magnetic exchange field, where the corner states can be fully spin polarized and moved into the bulk states. Focusing on the example of the C2N/CrI3 van der Waals heterostructure, we put forth a class of proximitized materials which enable the versatile control of corner states through strain-controlled magnetic proximity effects. Our work reveals another type of topological state, and provides a universal proposal for topological corner state modulations and applications.

关键词： First-principles calculations Topological materials Monolayer films Density functional theory Electronic structure Materials modeling Tight-binding model wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Stabilizing a hydrogen-rich superconductor at 1 GPa by charge transfer modulated virtual high-pressure effect

引用

Physical Review B 2023年第18期107卷 L180501-L180501页

作者： Miao Gao Peng-Jie Guo Huan-Cheng Yang Xun-Wang Yan Fengjie Ma Zhong-Yi Lu Tao Xiang Hai-Qing Lin Department of Physics School of Physical Science and Technology Ningbo University Zhejiang 315211 China School of Physics Zhejiang University Hangzhou 310058 China Department of Physics Renmin University of China Beijing 100872 China College of Physics and Engineering Qufu Normal University Shandong 273165 China The Center for Advanced Quantum Studies and Department of Physics Beijing Normal University Beijing 100875 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China Beijing Academy of Quantum Information Sciences Beijing 100193 China

Applying pressure around megabar is indispensable in the synthesis of high-temperature superconducting hydrides, such as H3S and LaH10. Stabilizing the high-pressure phase of hydride around ambient condition is a severe challenge. Based on the density-functional theory calculations, we give the first example that the structure of hydride CaBH5 predicted above 280 GPa can maintain its dynamical stability with pressure down to 1 GPa, by modulating the charge transfer from metal atoms to hydrogen atoms via the replacement of Ca with alkali metal atoms, e.g., Cs, in which the [BH5]2− anion shrinks along c axis and expands in the ab plane, experiencing an anisotropic virtual high pressure. This mechanism, namely charge transfer modulated virtual high-pressure effect, plays a vital role in enhancing the structural stability and leading to the reemergence of ambient-pressure-forbidden [BH5]2− anion around 1 GPa in CsBH5. Moreover, we find that CsBH5 is a strongly coupled superconductor, with transition temperature as high as 98 K, well above the liquid-nitrogen temperature. Our findings provide a novel mechanism to reduce the critical pressure required by hydrogen-rich compound without changing its crystal structure, and also shed light on searching ambient-pressure high-temperature superconductivity in metal borohydrides.

关键词： Electron-phonon coupling High-temperature superconductors Hydrides First-principles calculations wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Higher-order topological insulators in two-dimensional Dirac materials

引用

Physical Review Research 2021年第4期3卷 L042044-L042044页

作者： Yang Xue Hao Huan Bao Zhao Youhua Luo Zhenyu Zhang Zhongqin Yang School of Physics East China University of Science and Technology Shanghai 200237 China State Key Laboratory of Surface Physics and Key Laboratory of Computational Physical Sciences (MOE) & Department of Physics Fudan University Shanghai 200433 China Shandong Key Laboratory of Optical Communication Science and Technology School of Physics Science and Information Technology Liaocheng University Liaocheng 252059 China International Center for Quantum Design of Functional Materials (ICQD) Hefei National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei 230026 China

As a novel topological state, a higher-order topological insulator has attracted enormous interest, which in d spatial dimensions has gapless boundary states at (d−n) dimensions (integer n is larger than 1). Until now, merely few two-dimensional (2D) materials have been identified as higher-order topological insulators and their experimental confirmations are still absent. Here we propose a universal strategy of antidot engineering to realize second-order topological insulators (SOTIs) in 2D Dirac materials. Based on symmetry analysis, tight-binding model, and first-principles calculations, we demonstrate SOTIs in antidot-decorated Xene (X=C, Si,and Ge) by displaying its finite bulk quadrupole moment, weak topological edge states, and in-gap topological corner states. An inherent connection is established for the existing various mechanisms of the SOTIs, including quadrupole polarization, filling anomaly, and generalized Su-Schrieffer-Heeger model on a Kekulé lattice. The robustness of topological corner states of the SOTIs against edge perturbations and bulk disorders is explicitly demonstrated, rendering our strategy appealing to experimental realization of topological corner states.

关键词： Edge states First-principles calculations Topological materials Germanene Graphene Honeycomb lattice Density functional theory Symmetries Tight-binding model wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Quasinodal lines in rhombohedral magnetic materials

引用

Physical Review B 2021年第20期104卷 205128-205128页

作者： Rafael González-Hernández Erick Tuiran Bernardo Uribe Departamento de Física y Geociencias Universidad del Norte Km. 5 Vía Antigua Puerto Colombia Barranquilla 080020 Colombia Institut für Physik Johannes Gutenberg Universität Mainz D-55099 Mainz Germany Departamento de Matemáticas y Estadística Universidad del Norte Km. 5 Vía Antigua Puerto Colombia Barranquilla 080020 Colombia Max Planck Institut für Mathematik Vivatsgasse 7 53115 Bonn Germany

A well-established result in condensed matter physics states that materials crystallizing in symmetry groups containing glide reflection symmetries possess nodal lines on the energy bands. These nodal lines are topologically protected and appear on the fixed planes of the reflection in reciprocal space. In the presence of inversion symmetry, the energy bands are degenerate and the band crossings on the fixed plane may be one-dimensional, or may intersect in points, including the case of empty intersection. In the latter case, the crossing is partially or totally avoided, thus producing lines on reciprocal space where the energy gap may be small, and in the former, the nodal lines will endure, thus producing Dirac or double nodal lines. In addition, if the material crystallizes in a ferromagnetic phase where the glide reflection symmetry is broken, the nodal lines hybridize, thus defining lines in reciprocal space where the energy gap may be small. In this work, we concentrate our efforts on the study of nodal lines that hybridize due to magnetization; we have coined the term of quasinodal lines for those lines in reciprocal space where the energy gap is small (less than what can be detected experimentally ∼25 meV). We study magnetic trifluorides and trioxides which crystallize in magnetic space groups 167.107 and 161.71 and we show the existence of quasinodal lines on these materials. We furthermore show that whenever the quasinodal lines are located around the Fermi level then interesting charge and spin transport effects are induced and can be used to detect experimentally these lines. Of particular interest are the half-metallic ferromagnetic phases of PdF3 and LiCuF3 where the large signal of the anomalous Hall conductance is due to the presence of the quasinodal lines on the Fermi level.

关键词： Symmetry protected topological states Topological phases of matter Node-line semimetals Density functional approximations Topology wannier function methods

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：