检索结果-内蒙古大学图书馆

Three-dimensional quantum anomalous Hall effect in ferromagnetic insulators

Physical Review B 2018年第8期98卷 081101(R)-081101(R)页

作者： Y. J. Jin R. Wang B. W. Xia B. B. Zheng H. Xu Department of Physics & Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 People's Republic of China

The quantum anomalous Hall effect (QAHE) hosts the dissipationless chiral edge states associated with the nonzero Chern number, providing potentially significant applications in future spintronics. The QAHE usually occurs in a two-dimensional system with time-reversal symmetry breaking. In this Rapid Communication, we propose that the QAHE can exist in three-dimensional (3D) ferromagnetic insulators. By imposing inversion symmetry, we develop the topological constraints dictating the appearance of a 3D QAHE based on a parity analysis at the time-reversal invariant points in reciprocal space. Moreover, using first-principles calculations, we identify that 3D QAHE can be realized in a family of intrinsic ferromagnetic insulating oxides, including layered and nonlayered compounds that share a centrosymmetric structure with space group R3¯m (No. 166). The Hall conductivity is quantized to be −3e2hc with the lattice constant c along the c axis. The chiral surface sheet states are clearly visible and uniquely distributed on the surfaces that are parallel to the magnetic moment. Our findings open a promising pathway to realize the QAHE in 3D ferromagnetic insulators.

关键词： Ferromagnetism Quantum anomalous Hall effect Magnetic insulators

来源：评论

学校读者我要写书评

暂无评论

Ferroelectric order in hybrid organic-inorganic perovskite NH_(4)PbI_(3) with non-polar molecules and small tolerance factor

引用

npj Computational Materials 2023年第1期9卷 1726-1731页

作者： Jia-Bin Li Zhi-Kang Jiang Rui Wang Jin-Zhu Zhao Ruiqiang Wang Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials School of Physics and Telecommunication EngineeringSouth China Normal UniversityGuangzhou 510006PR China Guangdong-Hong Kong Joint Laboratory of Quantum Matter South China Normal UniversityGuangzhou 510006PR China Foshan(Southern China)Institute for New Materials Foshan 528300PR China Institute for Structure and Function and Department of Physics Chongqing UniversityChongqing 400044PR China Center of Quantum Materials and Devices Chongqing UniversityChongqing 400044PR China Center for Computational Science and Engineering Southern University of Science and TechnologyShenzhen 518055PR China

The appropriate theoretical picture of describing the ferroelectric order in hybrid organic-inorganic perovskite remains attractive and under intense *** rationalize the interaction between organic molecule sublattice and inorganic frame from *** systematic investigations on the NH_(4)PbI_(3),we show that the non-polar octahedral rotation dominates the process of stabilizing of the lattice with small value of tolerance *** direct coupling between molecules is *** the help of hydrogen bonding to the inorganic cage,molecule sublattice will eventually build long-range ferroelectric or anti-ferroelectric order under the constrain of the inorganic cage and further polarize the inorganic frame as the *** results also clarify that to build ferroelectricity the polar molecule is helpful but not *** the general rule for hybrid organic-inorganic perovskite,we identified the fundamental mechanism that can be considered as a critical pre-step forward to further controlling the related physics in functional materials.

关键词： inorganic ferroelectric polar

来源：评论

学校读者我要写书评

暂无评论

Robust Twin Pairs of Weyl Fermions in Ferromagnetic Oxides

引用

Physical Review Letters 2019年第5期122卷 057205-057205页

作者： B. W. Xia Y. J. Jin J. Z. Zhao Z. J. Chen B. B. Zheng Y. J. Zhao R. Wang H. Xu Department of Physics & Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People’s Republic of China Department of Physics South China University of Technology Guangzhou 510640 People’s Republic of China Institute for Structure and Function & Department of physics Chongqing University Chongqing 400044 People’s Republic of China

The ferromagnetic Weyl semimetals with inversion symmetry usually possess odd pairs of Weyl fermions. Here, we present an inversion eigenvalue argument to dictate the existence of even pairs of ferromagnetic Weyl fermions. We show, by a combination of first-principles calculations and symmetry analyses, that this exotic topological feature can be verified in ferromagnetic oxides in different space groups. In particular, a realistic candidate, i.e., hollandite RbCr4O8 with a high Curie temperature (∼295 K), hosts intriguing twin pairs of Weyl fermions, which are robustly stable against perturbations. Moreover, our effective model and symmetry analysis show that the twin pairs of Weyl fermions originate from a mirrored nodal ring pair. The nontrivial surface states and Fermi arcs of RbCr4O8 are clearly visible, further revealing the topological features. This work strengthens the understanding of the parity analysis in exploring ferromagnetic topological materials with unconventional fermionic excitations.

关键词： Ferromagnetism Symmetry protected topological states Weyl fermions Weyl semimetal First-principles calculations k dot p method

来源：评论

学校读者我要写书评

暂无评论

Ideal intersecting nodal-ring phonons in bcc C8

引用

Physical Review B 2018年第22期98卷 220103(R)-220103(R)页

作者： Y. J. Jin Z. J. Chen B. W. Xia Y. J. Zhao R. Wang H. Xu Department of Physics and Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China Department of Physics South China University of Technology Guangzhou 510640 People's Republic of China Institute for Structure and Function and Department of Physics Chongqing University Chongqing 400044 People's Republic of China

Carbon, a basic versatile element in our universe, exhibits rich varieties of allotropic phases, most of which possess promising nontrivial topological fermions. In this work, we identify a distinct topological phonon phase in a realistic carbon allotrope with a body-centered cubic structure, termed bcc C8. We show by symmetry arguments and effective model analysis that there are three intersecting phonon nodal rings perpendicular to each other in different planes. The intersecting phonon nodal rings are protected by time-reversal and inversion symmetries, which quantize the corresponding Berry phase into integer multiples of π. Unlike the electron systems, the phonon nodal rings in bcc C8 are guaranteed to remain gapless due to the lack of spin-orbital coupling. The nearly flat drumhead surface states projected on semi-infinite (001) and (110) surfaces of bcc C8 are clearly visible. Our findings not only discover promising nodal ring phonons in a carbon allotrope but also provide emergent avenues for exploring topological phonons beyond fermionic electrons in carbon-allotropic structures with attractive features.

关键词： Optical phonons Phonons Topological phases of matter Node-line semimetals Topological materials

来源：评论

学校读者我要写书评

暂无评论

Ferromagnetic Weyl fermions in CrO2

引用

Physical Review B 2018年第19期97卷 195157-195157页

作者： R. Wang Y. J. Jin J. Z. Zhao Z. J. Chen Y. J. Zhao H. Xu Department of Physics and Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Rebuplic of China Institute for Structure and Function and Department of Physics Chongqing University Chongqing 400044 People's Rebuplic of China Department of Physics South China University of Technology Guangzhou 510640 People's Rebuplic of China

The interplay between symmetry and magnetization directions in ferromagnetic materials provides an exotic platform to investigate the symmetry-protected topological order. In this work, we propose that unexpected ferromagnetic topological features, such as triple fermions and type-I and type-II Weyl fermions, can emerge in three phases of chromium dioxide (CrO2), i.e., rutile CrO2, orthorhombic CrO2 of the CaCl2 type, and pyrite CrO2. Using first-principles calculations and topology analysis, we reveal that the breaking of the spin-rotation symmetry leads to tunable Weyl fermions that are robust against spin-orbital coupling, which can be easily realized by manipulating the magnetization direction. In particular, rutile CrO2, a well-known half-metallic ferromagnet used in magnetic recording tapes, is an ideal candidate to overcome obstacles of studying ferromagnetic topological semimetals in experiments. The topological features in different phases of CrO2 may bridge the gap between the band topology and local chemical bonding. Our findings substantially advance the experimental realization of ferromagnetic Weyl semimetals. More importantly, room-temperature ferromagnetic Weyl fermions in CrO2 may give rise to promising applications related to the topological phenomena in industry.

关键词： Ferromagnetism Topological materials Half-metals Weyl semimetal First-principles calculations Symmetries in condensed matter Wannier function methods

来源：评论

学校读者我要写书评

暂无评论

Large-gap quantum anomalous Hall phase in hexagonal organometallic frameworks

引用

Physical Review B 2018年第24期98卷 245127-245127页

作者： Yuanjun Jin Zhongjia Chen Bowen Xia Yujun Zhao Rui Wang Hu Xu Department of Physics & Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China Department of Physics South China University of Technology Guangzhou 510640 People's Republic of China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 People's Republic of China

The nontrivial band gap plays a critical role in quantum anomalous Hall (QAH) insulators. In this work, we propose that the intrinsic QAH phase with sizable band gaps up to 367 meV is achieved in two-dimensional hexagonal organometallic frameworks (HOMFs). Based on first-principles calculations and effective model analysis, we uncover that these large band gaps in transition metal based HOMFs are opened by strong spin-orbital coupling of the localized 4d or 5d electrons. Importantly, we reveal that Coulomb correlations can further significantly enhance the nontrivial band gaps. In addition, we suggest a possible avenue to grow these organometallic QAH insulators on a semiconducting SiC(111) substrate, and the topological features are perfectly preserved due to the van der Waals interaction. Our work shows that the correlation remarkably enhances the nontrivial band gaps, providing exotic candidates to realize the QAH states at high temperatures.

关键词： Ferromagnetism Quantum anomalous Hall effect Topological materials Electron-correlation calculations

来源：评论

学校读者我要写书评

暂无评论

Hourglass phonons jointly protected by symmorphic and nonsymmorphic symmetries

引用

Physical Review B 2021年第6期104卷 L060301-L060301页

作者： Baobing Zheng Fangyang Zhan Xiaozhi Wu Rui Wang Jing Fan College of Physics and Optoelectronic Technology & Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center Baoji University of Arts and Sciences Baoji 721016 People's Republic of China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 People's Republic of China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing 400044 People's Republic of China Center for Quantum Materials and Devices Chongqing University Chongqing 400044 People's Republic of China Center for Computational Science and Engineering Southern University of Science and Technology Shenzhen 518055 People's Republic of China

Hourglass dispersion is generally believed to be solely protected by nonsymmorphic symmetries, because these symmetries can introduce high-dimensional projective representations. Here, based on symmetry arguments, we propose that the hourglass dispersion can be jointly protected by symmorphic and nonsymmorphic symmetries, instead of the conventional nonsymmorphic symmetry. Moreover, using first-principles calculations, we realize our proposal in the phonon spectra of realistic materials that share an antiperovskite structure with space group P4/nmm. Importantly, the neck points of these hourglass dispersions trace out two nodal rings tangential to four nodal lines, forming a unique hourglass nodal cage in the bulk Brillouin zone. The Berry phase analysis reveals the nontrivial topology of these nodal rings and nodal lines. Furthermore, nontrivial surface states and isofrequency surface arcs are visible, facilitating their experimental confirmation of such exotic quasiparticles. work not only offers different insights into the hourglass dispersion, but also expands aspects for studying promising topological quasiparticles in condensed-matter systems.

关键词： Electronic structure Lattice dynamics Phonons Symmetry protected topological states Node-line semimetals First-principles calculations

来源：评论

学校读者我要写书评

暂无评论

Flexible Control of Chiral Superconductivity in Optically Driven Nodal Point Superconductors with Antiferromagnetism

引用

Physical Review Letters 2024年第24期133卷 246606-246606页

作者： Zhen Ning Da-Shuai Ma Junjie Zeng 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 and Center of Quantum Materials and Devices Chongqing University Chongqing 400044 People’s Republic of China

Recent studies have attracted widespread attention on magnet-superconductor hybrid systems with emergent topological superconductivity. Here, we present the Floquet engineering of realistic two-dimensional topological nodal-point superconductors that are composed of antiferromagnetic monolayers in proximity to an s-wave superconductor. We show that Floquet chiral topological superconductivity arises due to light-induced breaking of the effective time-reversal symmetry. More strikingly, we find that the Floquet chiral topological superconducting phases can be flexibly controlled by irradiating elliptically polarized light, with the photon-dressed quasienergy spectrum carrying different Chern numbers. Such optically switchable topological transitions arise from the simultaneous creations (or annihilations) of valley pairs, which are attributed to the intertwining with magnetic symmetry, superconductivity, and topology. Our findings provide a feasible approach for achieving the Floquet chiral topological superconductivity with flexible tunability, which would draw extensive attention in experiments.

关键词： Antiferromagnetism

来源：评论

学校读者我要写书评

暂无评论

Realization of kagome lattice and superconductivity in topological electrides

引用

Physical Review B 2024年第5期110卷 054511-054511页

作者： Yu-Hao Wei Hao-Dong Liu Da-Shuai Ma Hong-Kuan Yuan Bao-Tian Wang Min-Quan Kuang Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics and School of Physical Science and Technology Chinese Academy of Sciences Beijing 100049 People's Republic of China Dongguan 523803 People's Republic of China Institute for Structure and Function & Department of Physics & Chongqing Key Laboratory for Strongly Coupled Physics Center of Quantum Materials and Devices

Realization of kagome lattice, and hence achieving specific performance, is a challenging issue in condensed matter physics. The corner-sharing triangles of kagome lattice are normally comprised of real atoms occupying certain Wyckoff sites. Here, we propose that the excess electrons in layered electrides Mg3N and Mg3O build the two-dimensional kagome lattices. The interstitial electrons further contribute to the nontrivial band topology, i.e., the Dirac points and the Dirac nodal lines in Mg3N and Mg3O. Further, the in-plane coupling between the electronic orbitals and the atomic vibrational modes dominate the electron-phonon coupling, and yield superconducting critical temperatures approaching 2.0 and 2.2 K for Mg3N and Mg3O, respectively. This work proposes a feasible scheme to construct kagome lattices by interstitial quasiatoms and provides a promising platform to explore the superconductivity and nontrivial band topology in kagome electrides.

关键词： Superconductivity Kagome lattice Topological materials First-principles calculations

来源：评论

学校读者我要写书评

暂无评论

Performance of optical imaging capillary plate gas detector with synchrotron radiation

Performance of optical imaging capillary plate gas detector ...

引用

作者： Tokanai, Fuyuki Sakurai, Hirohisa Gunji, Shuichi Toyokawa, Hidenori Suzuki, Masayo Tanida, Hajime Kishimoto, Shunji Department of Physics Faculty of Science Yamagata University Yamagata 990-8560 Japan Information and Cell Function PRESTO JST Tokyo 103-0028 Japan Radiation Research Institute Sayo-gun Hyogo 679-5198 Japan Institute of Material Structure Science KEK Ibaraki 305-0801 Japan

We have been developing an X-ray photoelectron tracking imager based on a glass capillary plate (CP) gas detector for cosmic X-ray polarimetry applications. The optical imaging system consists of a CP gas detector filled with a noble-gas mixture and a cooled CCD camera coupled to an optical lens system. The performance of the optical imaging CP gas detector as an X-ray polarimeter was investigated with highly polarized, well-monochromized, and well-collimated X-ray beams at the synchrotron radiation facilities in SPring-8 and KEK-PF. Owing to the fine imaging capability of the optical imaging CP gas detector, images of X-ray photoelectron tracks were clearly observed for the polarized X-rays. A modulation factor of 26% was obtained for a 15 keV polarized X-ray beam, for which the energy resolution was 13%. We report on the properties of the optical imaging CP gas detector as an X-ray polarimeter and describe the outlook on future developments on the basis of the measured characteristics and the results of Monte Carlo simulations. © 2006 IEEE.

关键词： Imaging techniques

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：