检索结果-内蒙古大学图书馆

Design monolayer iodinenes based on halogen bond and tiling theory

学校读者我要写书评

暂无评论

Physical Review B 2024年第12期109卷 125423-125423页

作者： Kejun Yu Yichen Liu Botao Fu Run-Wu Zhang Da-shuai Ma Xiao-ping Li Zhi-Ming Yu Cheng-Cheng Liu Yugui Yao 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 College of Physics and Electronic Engineering Center for Computational Sciences Sichuan Normal University Chengdu 610068 China Institute for Structure and Function and Department of Physics and 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 School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China

Xenes, two-dimensional (2D) monolayers composed of a single element, with graphene as a typical representative, have attracted widespread attention. Most of the previous Xenes, X from group-IIIA to group-VIA elements, have bonding characteristics of covalent bonds. In this paper, we unveil the pivotal role of a halogen bond, which is a distinctive type of bonding with interaction strength between that of a covalent bond and a van der Waals interaction, in 2D group-VIIA monolayers. Combing the ingenious non-edge-to-edge tiling theory and state-of-the-art ab initio method with refined local density functional M06-L, we provide a precise and effective bottom-up construction of 2D iodine monolayer sheets, iodinenes, primarily governed by halogen bonds, and successfully design a category of stable iodinenes encompassing herringbone, Pythagorean, gyrated truncated hexagonal, i.e., diatomic kagome, and gyrated hexagonal tiling patterns. These iodinene structures exhibit a wealth of properties, such as nontrivial topology, flat bands and fascinating optical characteristics, offering valuable insights and guidance for future experimental investigations. Our paper not only unveils the unexplored halogen bonding mechanism in 2D materials but also opens an avenue for designing other noncovalent bonding 2D materials.

关键词： Electronic structure Structural properties Topological materials 2-dimensional systems Two-dimensional electron system Density functional theory

Recipe for generating Weyl semimetals with extended topologically protected features

学校读者我要写书评

暂无评论

Physical Review B 2017年第12期96卷 121104(R)-121104(R)页

作者： R. Wang J. Z. Zhao Y. J. Jin W. P. Xu L.-Y. Gan X. Z. Wu H. Xu S. Y. Tong Department of Physics South University of Science and Technology of China Shenzhen 518055 Peoples Republic of China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 Peoples Republic of China Dalian Institute of Chemical Physics Chinese Academy of Sciences 116023 Dalian Peoples Republic of China Key Laboratory of Advanced Technology of Materials (Ministry of Education) Superconductivity and New Energy R&D Center Southwest Jiaotong University Chengdu 610031 Sichuan Peoples Republic of China School of Science and Engineering The Chinese University of Hong Kong (Shenzhen) 518172 Shenzhen Peoples Republic of China

We present a recipe that leads to Weyl semimetals with extended topologically protected features. We show that compounds in a family that possess time-reversal symmetry and share a noncentrosymmetric cubic structure with the space group F−43m (no. 216) host robust Weyl fermions with extended and easily measurable protected features. The candidates in this family are compounds with different chemical formulas, AB2, ABC, ABC2, and ABCD, and their Fermi levels are predominantly populated by nontrivial Weyl fermions. Symmetry of the system requires that the Weyl nodes with opposite chirality are well separated in momentum space. Adjacent Weyl points have the same chirality; thus these Weyl nodes would not annihilate each other with respect to lattice perturbations. As Fermi arcs and surface states connect Weyl nodes with opposite chirality, the large separation of the latter in momentum space guarantees the appearance of very long arcs and surface states. This work demonstrates that the use of system symmetry by first-principles calculations is a powerful approach for discovering new Weyl semimetals with attractive features whose protected fermions may be candidates of many applications.

关键词： Topological materials Weyl semimetal k dot p method

Floquet valley-polarized quantum anomalous hall state in nonmagnetic heterobilayers

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Zhan, Fangyang Ning, Zhen Gan, Li-Yong Zheng, Baobing Fan, Jing Wang, Rui Institute for Structure and Function Department of Physics Chongqing University Chongqing400044 China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing400044 China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen518055 China Center for Quantum Materials and Devices Chongqing University Chongqing400044 China College of Physics and Optoelectronic Technology Baoji University of Arts and Sciences Baoji721016 China

The valley-polarized quantum anomalous Hall (VQAH) state, which forwards a strategy for combining valleytronics and spintronics with nontrivial topology, attracts intensive interest in condensedmatter physics. So far, the explored VQAH states have still been limited to magnetic systems. Here, using the low-energy effective model and Floquet theorem, we propose a different mechanism to realize the Floquet VQAH state in nonmagnetic heterobilayers under light irradiation. We then realize this proposal via first-principles calculations in transition metal dichalcogenide heterobilayers, which initially possess the time-reversal invariant valley quantum spin Hall (VQSH) state. By irradiating circularly polarized light, the time-reversal invariant VQSH state can evolve into the VQAH state, behaving as an optically switchable topological spin-valley filter. These findings not only offer a rational scheme to realize the VQAH state without magnetic orders, but also pave a fascinating path for designing topological spintronic and valleytronic devices. Copyright © 2021, The Authors. All rights reserved.

关键词： Landforms

Single pair of charge-two high-fold fermions with type-II van Hove singularities on the surface of ultralight chiral crystals

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Xiao, Xiaoliang Jin, Yuanjun Ma, Da-Shuai Wei, Haoran Fan, Jing Wang, Rui Wu, Xiaozhi Institute for Structure and Function Department of Physics Chongqing University Chongqing400044 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Center of Quantum materials and devices Chongqing University Chongqing400044 China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen518055 China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing400044 China

The realization of single-pair chiral fermions in Weyl systems remains challenging in topology physics, especially for the systems with higher chiral charges C. In this work, based on the symmetry analysis, low-energy effective model, and first-principles calculations, we identify the single-pair high-fold fermions in chiral cubic lattices. We first derive the minimal lattice model that exhibits a single pair of Weyl points with the opposite chiral charges of C = ±2. Furthermore, we show the ultralight chiral crystal P4332-type LiC2 and its mirror enantiomer as high-quality candidate materials, which exhibit large energy windows to surmount the interruption of irrelevant bands. Since two enantiomers are connected by the mirror symmetry, we observe the opposite chiral charges C and the reversal of the Fermi arc velocities, showing the correspondence of chirality in the momentum space and the real space. In addition, we also reveal type-II van Hove singularities on the helicoid surfaces, which may induce chirality-locked charge density waves on the crystal surface. Our work not only provides a promising platform for controlling the sign of topological charge through the structural chirality but also facilitates the exploration of electronic correlations on the surface of ultralight chiral crystals. Copyright © 2023, The Authors. All rights reserved.

关键词： Enantiomers

Gyrotropic Magnetic Effect in Black Phosphorus Irradiated with Bicircular Light

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Zhan, Fangyang Jin, Xin Ma, Da-Shuai Fan, Jing Yu, Peng Xu, Dong-Hui Wang, Rui Institute for Structure and Function Department of Physics Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing400044 China College of Mathematics and Statistics Chongqing University Chongqing400044 China College of Physics and Electronic Engineering Chongqing Normal University Chongqing400044 China Center of Quantum materials and devices Chongqing University Chongqing400044 China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen518055 China

The gyrotropic magnetic effect, manifesting as a gyropropic current under a slowly-varying magnetic field, represents a fundamental property of Bloch electrons on the Fermi surface;however, it has not been observed in experiments. Here, we theoretically propose that Floquet engineering with bicircular light (BCL), which is a superposition of two opposite chiral waves of circularly polarized light with an integer frequency ratio, presents a fascinating strategy to generate and manipulate the gyrotropic magnetic effect in nodal line semimetals. The tailoring spatial symmetry of BCL irradiation can induce a topological transition from a nodal line semimetallic phase to a Weyl semimetallic phase characterized by a minimum number of misaligned Weyl nodes, resulting in the generation of gyrotropic current when a slowly oscillating magnetic field is applied. Moreover, using first-principles calculations, we show that the compressed black phosphorus under irradiation of BCL is an ideal candidate to realize the large gyropropic current with great advantages. Our work not only broadens potential candidate materials for achieving the experimentally accessible gyropropic current, but also provides deeper insights into the interplay between topological phenomena and light manipulation of symmetries. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

Magnetic field induced valley-polarized quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Zhan, Fangyang Zheng, Baobing Xiao, Xiaoliang Fan, Jing Wu, Xiaozhi Wang, Rui Institute for Structure and Function Department of Physics Chongqing University Chongqing400044 China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing400044 China College of Physics and Optoelectronic Technology Baoji University of Arts and Sciences Baoji721016 China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen518055 China Center for Quantum Materials and Devices Chongqing University Chongqing400044 China

The valley-polarized quantum anomalous Hall effect (VQAHE) attracts intensive interest since it uniquely combines valleytronics and spintronics with nontrivial band topology. Here, based on first-principles calculations and Wannier-function-based tight-binding (WFTB) model, we reveal that valley-based Hall effects and especially the VQAHE induced by external magnetic fields can occur in two-dimensional (2D) ferromagnetic van der Waals heterostructures (vdWHs). The results show that considerable valley-splitting derived from the Zeeman exchange energy drives these vdWHs generating the valley anomalous Hall effect and then the VQAHE. The chiral edge states and quantized Hall conductance are utilized to confirm the presence of VQAHE. Besides, it is also found that external electric fields (or tuning interlayer distances) can facilitate the realization of VQAHE, and thus we present a phase diagram in a broad parameter regime of magnetic fields and electric fields (or interlayer distances). Our work not only offers a class of ferromagnetic vdWHs to realize various valley-based Hall phases, but also can guide advancements for designing topological devices with spin-valley filtering effects based on the VQAHE. Copyright © 2021, The Authors. All rights reserved.

关键词： Landforms

Floquet Engineering of Nonequilibrium Valley-Polarized Quantum Anomalous Hall Effect with Tunable Chern Number

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Zhan, Fangyang Zeng, Junjie Chen, Zhuo Jin, Xin Fan, Jing Chen, Tingyong Wang, Rui Institute for Structure and Function Department of Physics Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing400044 China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen518055 China Shenzhen Insitute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Center of Quantum materials and devices Chongqing University Chongqing400044 China

Numerous attempts have been made so far to explore the quantum anomalous Hall effect (QAHE), but the ultralow observed temperature strongly hinders its practical applications. Hence, it is of great interest to go beyond the existing paradigm of QAHE. Here, we propose that Floquet engineering offers a strategy to realize the QAHE via hybridization of Floquet-Bloch bands. Based on first-principles calculations and Floquet theorem, we unveil that nonequilibrium valley-polarized QAHE (VP-QAHE), independent of magnetic orders, is widely present in ferromagnetic and nonmagnetic members of two-dimensional family materials MSi2Z4 (M = Mo, W, V;Z = N, P, As) by irradiating circularly polarized light (CPL). Remarkably, by tuning the frequency, intensity, and handedness of incident CPL, the Chern number of VP-QAHE is highly tunable and up to C = ±4. We reveal that such Chern number tunable VP-QAHE attributes to light-induced trigonal warping and multiple band inversion at different valleys. The valley-resolved chiral edge states and quantized plateau of Hall conductance, which facilitates the experimental measurement, are visible inside the global band gap. Our work not only establishes Floquet Engineering of nonequilibrium VP-QAHE with tunable Chern number in realistic materials, but also provides a promising avenue to explore emergent topological phases under light irradiation. Copyright © 2022, The Authors. All rights reserved.

关键词： Energy gap

Photoinduced quantum anomalous hall states in the topological anderson insulator

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Ning, Zhen Zheng, Baobing Xu, Dong-Hui Wang, Rui Institute for Structure and Function Department of Physics Chongqing University Chongqing400044 China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing400044 China College of Physics and Optoelectronic Technology Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center Baoji University of Arts and Sciences Baoji721016 China Department of Physics Hubei University Wuhan430062 China Center for Quantum Materials and Devices Chongqing University Chongqing400044 China

The realization of the quantum anomalous Hall (QAH) effect without magnetic doping attracts intensive interest since magnetically doped topological insulators usually possess inhomogeneity of ferromagnetic order. Here, we propose a different strategy to realize intriguing QAH states aris- ing from the interplay of light and non-magnetic disorder in two-dimensional topologically trivial systems. By combining the Born approximation and Floquet theory, we show that a time-reversal invariant disorder-induced topological insulator, known as the topological Anderson insulator (TAI), would evolve into a time-reversal broken TAI and then into a QAH insulator by shining circularly polarized light. We utilize spin and charge Hall conductivities, which can be measured in experi- ments directly, to distinguish these three different topological phases. This work not only offers an exciting opportunity to realize the high-temperature QAH effect without magnetic orders, but also is important for applications of topological states to spintronics. Copyright © 2021, The Authors. All rights reserved.

关键词： Electric insulators

Tunable ferromagnetic Weyl fermions from a hybrid nodal ring

学校读者我要写书评

暂无评论

npj Computational Materials 2019年第1期5卷 516-522页

作者： Baobing Zheng Bowen Xia Rui Wang Jinzhu Zhao Zhongjia Chen Yujun Zhao Hu Xu Department of Physics and Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology518055 ShenzhenP.R.China School of Physics and Technology Wuhan University430072 WuhanP.R.China College of Physics and Optoelectronic Technology and Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center Baoji University of Arts and Sciences721016 BaojiP.R.China Institute for Structure and Function and Department of physics Chongqing University400044 ChongqingP.R.China Department of Physics South China University of Technology510640 GuangzhouP.R.China Center for Quantum Computing Peng Cheng Laboratory518055 ShenzhenP.R.China

Realization of nontrivial band topology in condensed matter systems is of great interest in recent *** first-principles calculations and symmetry analysis,we propose an exotic topological phase with tunable ferromagnetic Weyl fermions in a halfmetallic oxide CrP_(2)O_(7).In the absence of spin–orbit coupling(SOC),we reveal that CrP_(2)O_(7) possesses a hybrid nodal *** SOC is present,the spin-rotation symmetry is *** a result,the hybrid nodal ring shrinks to discrete nodal points and forms different types of Weyl *** Fermi arcs projected on the(100)surface are clearly visible,which can contribute to the experimental study for the topological properties of CrP_(2)O_(7).In addition,the calculated quasiparticle interference patterns are also highly desirable for the experimental study of CrP_(2)O_(7).Our findings provide a good candidate of ferromagnetic Weyl semimetals,and are expected to realize related topological applications with their attracted features.

关键词： ferromagnetic nodal topological