检索结果-内蒙古大学图书馆

Magnetic anisotropy of the van der Waals ferromagnet Cr2Ge2Te6 studied by angular-dependent x-ray magnetic circular dichroism

引用

Physical Review Research 2022年第1期4卷 013139-013139页

作者： M. Suzuki B. Gao G. Shibata S. Sakamoto Y. Nonaka K. Ikeda Z. Chi Y.-X. Wan T. Takeda Y. Takeda T. Koide A. Tanaka M. Kobayashi S.-W. Cheong A. Fujimori Department of Physics The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Rutgers Center for Emergent Materials and Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08854 USA Department of Applied Physics Tokyo University of Science Katsushika-ku Tokyo 125-8585 Japan Department of Electrical Engineering and Information Systems The University of Tokyo Bunkyo-ku Tokyo 113-8656 Japan Materials Sciences Research Center Japan Atomic Energy Agency (JAEA) Sayo Hyogo 679-5148 Japan Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba Ibaraki 305-0801 Japan Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-hiroshima 739-8530 Japan Center for Spintronics Research Network The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Department of Applied Physics Waseda University Shinjuku-ku Tokyo 169-8555 Japan

The van der Waals ferromagnet Cr2Ge2Te6 (CGT) has a two-dimensional crystal structure where each layer is stacked through van der Waals force. We have investigated the nature of the ferromagnetism and the weak perpendicular magnetic anisotropy (PMA) of CGT by means of x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD) studies of CGT single crystals. The XMCD spectra at the Cr L2,3 edge for different magnetic field directions were analyzed on the basis of the cluster-model multiplet calculation. The Cr valence is confirmed to be 3+ and the orbital magnetic moment is found to be nearly quenched, as expected for the high-spin t2g3 configuration of the Cr3+ ion. A large (∼0.2 eV) trigonal crystal-field splitting of the t2g level caused by the distortion of the CrTe6 octahedron has been revealed, while the single-ion anisotropy (SIA) of the Cr atom is found to have a sign opposite to the observed PMA and too weak compared to the reported anisotropy energy. The present result suggests that anisotropic exchange coupling between the Cr atoms through the ligand Te 5p orbitals having strong spin-orbit coupling has to be invoked to explain the weak PMA of CGT, as in the case of the strong PMA of CrI3.

关键词： Electronic structure Magnetic anisotropy 2-dimensional systems Magnetic semiconductors Cluster models X-ray magnetic circular dichroism

来源：评论

学校读者我要写书评

暂无评论

Vertical Grain-Shape engineering for High-Efficiency and Stable Perovskite Solar Cells

SSRN

引用

SSRN 2023年

作者： Shi, Yifeng Zheng, Yifan Xiao, Xun Wang, Pengxiang Zhang, Guodong Li, Qingyuan Zhang, Ge Shao, Yuchuan School of Microelectronics Shanghai University Shanghai201800 China Key Laboratory of Materials for High-Power Laser Chinese Academy of Sciences Shanghai201800 China Laboratory of Thin Film Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China School of Physics and Optoelectronic Engineering Hangzhou Institute for Advanced Study UCAS Hangzhou310024 China Department of Applied Physical Sciences University of North Carolina Chapel HillNC27599 United States

In recent years, perovskite solar cells have undergone rapid improvements in power conversion efficiency (PCE), advancing the development of next-generation photovoltaic technology. However, the presence of interfacial defects, which are prevalent during the film formation process, poses a persistent hurdle to the further improvement of device performance. While defects issues could be alleviated by introducing passivation strategies, the non-uniform dimensions of the top and bottom grain size may still result in unbalanced charge transport. Here, we present a vertical grain-shape engineering (VGE) approach based on anilinium hypophosphite (AHP) to control the vertical growth of perovskite grains. We have successfully fabricated a pinhole-free perovskite film with monolithic crystalline structures, demonstrating uniform grain sizes exceeding 2 micrometers at both the top and bottom surfaces. A champion PCE of 22.14% and 18.06% has been obtained for small-scale (0.08cm2) and mini-module (aperture area of 14 cm2) blade-coated FAPbI3-based PSCs, respectively. © 2023, The Authors. All rights reserved.

关键词： Morphology

来源：评论

学校读者我要写书评

暂无评论

Chiral anomaly and Weyl orbit in three-dimensional Dirac semimetal Cd3As2 grown on Si

引用

Nanotechnology 2024年第16期35卷 165002-165002页

作者： Lin, Wei-Chen Tsai, Peng-Ying Zou, Jia-Zhu Lee, Jie-Ying Kuo, Chun-Wei Lee, Hsin-Hsuan Pan, Ching-Yang Yang, Cheng-Hsueh Chen, Sheng-Zong Wang, Jyh-Shyang Jiang, Pei-Hsun Liang, Chi-Te Chuang, Chiashain Taiwan International Graduate Program Academia Sinica Taipei115 Taiwan Department of Engineering and System Science National Tsing Hua University Hsinchu300 Taiwan Graduate Institute of Applied Physics National Taiwan University Taipei106 Taiwan National Taiwan University Taipei106 Taiwan Department of Electronic Engineering Chung Yuan Christian University Taoyuan320 Taiwan Department of Physics Chung Yuan Christian University Taoyuan320 Taiwan Department of Physics National Taiwan Normal University 106 Taiwan Research Center for Semiconductor Materials and Advanced Optics Chung Yuan Christian University Taoyuan320 Taiwan

Preparing Cd3As2, which is a three-dimensional (3D) Dirac semimetal in certain crystal orientation, on Si is highly desirable as such a sample may well be fully compatible with existing Si CMOS technology. However, there is a dearth of such a study regarding Cd3As2 films grown on Si showing the chiral anomaly. Here, for the first time, we report the novel preparation and fabrication technique of a Cd3As2 (112) film on a Si (111) substrate with a ZnTe (111) buffer layer which explicitly shows the chiral anomaly with a nontrivial Berry’s phase of π. Despite the Hall carrier density ( n 3 D ≈ 9.42 × 10 17 cm−3) of our Cd3As2 film, which is almost beyond the limit for the portents of a 3D Dirac semimetal to emerge, we observe large linear magnetoresistance in a perpendicular magnetic field and negative magnetoresistance in a parallel magnetic field. These results clearly demonstrate the chiral magnetic effect and 3D Dirac semimetallic behavior in our silicon-based Cd3As2 film. Our tailoring growth of Cd3As2 on a conventional substrate such as Si keeps the sample quality, while also achieving a low carrier concentration. © 2024 IOP Publishing Ltd.

关键词： II-VI semiconductors

来源：评论

学校读者我要写书评

暂无评论

Optical conductivity of the Majorana mode at the s- and d-wave topological superconductor edge

arXiv

引用

arXiv 2024年

作者： Kamra, Lina Johnsen Lu, Bo Linder, Jacob Tanaka, Yukio Nagaosa, Naoto Center for Quantum Spintronics Department of Physics Norwegian University of Science and Technology TrondheimNO-7491 Norway Departamento de Física Téorica de la Materia Condensada Universidad Autónoma de Madrid MadridE-28049 Spain Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Center for Joint Quantum Studies Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Department of Physics Tianjin University Tianjin300354 China Department of Applied Physics Nagoya University Nagoya464-8603 Japan Research Center for Crystalline Materials Engineering Nagoya University Nagoya464-8603 Japan Saitama Wako351-0198 Japan Fundamental Quantum Science Program TRIP Headquarters RIKEN Wako351-0198 Japan

The Majorana fermion offers fascinating possibilities such as non-Abelian statistics and non-local robust qubits, and hunting it is one of the most important topics in current condensed matter physics. Most of the efforts have been focused on the Majorana bound state at zero energy in terms of scanning tunneling spectroscopy searching for the quantized conductance. On the other hand, a chiral Majorana edge channel appears at the surface of a three-dimensional topological insulator when engineering an interface between proximityinduced superconductivity and ferromagnetism. Recent advances in microwave spectroscopy of topological edge states open a new avenue for observing signatures of such Majorana edge states through the local optical conductivity. As a guide to future experiments, we show how the local optical conductivity and density of states present distinct qualitative features depending on the symmetry of the superconductivity, that can be tuned via the magnetization and temperature. In particular, the presence of the Majorana edge state leads to a characteristic non-monotonic temperature dependence achieved by tuning the magnetization. Copyright © 2024, The Authors. All rights reserved.

关键词： Topological insulators

来源：评论

学校读者我要写书评

暂无评论

Cavity-mediated superthermal phonon correlations in the ultrastrong coupling regime

arXiv

引用

arXiv 2024年

作者： Kim, Dasom Hou, Jin Lee, Geon Agrawal, Ayush Kim, Sunghwan Zhang, Hao Bao, Di Baydin, Andrey Wu, Wenjing Tay, Fuyang Huang, Shengxi Chia, Elbert E.M. Kim, Dai-Sik Seo, Minah Mohite, Aditya D. Hagenmüller, David Kono, Junichiro Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Sensor System Research Center Korea Institute of Science and Technology Seoul02792 Korea Republic of Department of Physics and Astronomy Seoul National University Seoul08826 Korea Republic of Department of Chemical and Biomolecular Engineering Rice University Houston77005 United States Ulsan44919 Korea Republic of Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Smalley–Curl Institute Rice University HoustonTX77005 United States Rice Advanced Materials Institute Rice University HoustonTX77005 United States KU–KIST Graduate School of Converging Science and Technology Korea University Seoul02841 Korea Republic of Université de Strasbourg CNRS Strasbourg67200 France Department of Physics and Astronomy Rice University HoustonTX77005 United States

Phonons, or vibrational quanta, are behind some of the most fundamental physical phenomena in solids, including superconductivity, Raman processes, and broken-symmetry phases. It is therefore of fundamental importance to find ways to harness phonons for controlling these phenomena and developing novel quantum technologies. However, the majority of current phonon control techniques rely on the use of intense external driving fields or strong anharmonicities, which restricts their range of applications. Here, we present a scheme for controlling the intensity fluctuations in phonon emission at room temperature based on multimode ultrastrong light–matter coupling. The multimode ultrastrong coupling regime is achieved by coupling two optical phonon modes in lead halide perovskites to an array of nanoslots, which operates as a single-mode cavity. The extremely small mode volume of the nanoslots enables unprecedented coupling strengths in a cavity phonon-polariton system. In the far-detuned, low-cavity-frequency regime, we demonstrate that the nanoslot resonator mediates an effective coupling between the phonon modes, resulting in superthermal phonon bunching in thermal equilibrium, both within the same mode and between different modes. Experimental results are in good agreement with a multimode Hopfield model. Our work paves the way for the tailoring of phonons to modify charge and energy transport in perovskite materials, with potential applications in light-collecting or emitting devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Perovskite

来源：评论

学校读者我要写书评

暂无评论

Terahertz Landau Polaritons in Nano-slots: Ultrastrong Coupling under Extreme Spatial Confinement

Terahertz Landau Polaritons in Nano-slots: Ultrastrong Coupl...

引用

International Conference on Infrared and Millimeter Waves

作者： Dasom Kim Sunghwan Kim Dukhyung Lee Shuang Liang Fuyang Tay Michael J. Manfra Dai-Sik Kim Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston TX USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston TX USA Department of Physics Long-wavelength Nanotechnology Laboratory and Quantum Photonics Institute Ulsan National Institute of Science and Technology (UNIST) Ulsan South Korea Department of Physics and Astronomy Purdue University West Lafayette IN USA Birck Nanotechnology Center Purdue University West Lafayette IN USA Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette IN USA School of Materials Engineering Purdue University West Lafayette IN USA Department of Physics and Astronomy Rice University Houston TX USA Department of Material Science and NanoEngineering Rice University Houston TX USA

We report ultrastrong coupling of the cyclotron resonance of a two-dimensional electron gas in a GaAs quantum well to terahertz cavity photons under extreme confinement to the nanometer scale. This was realized by an array of nano-slots fabricated close to the quantum well layer on the GaAs substrate. Our terahertz magnetospectroscopic measurements revealed two polariton branches as a function of applied magnetic field. While the photon-like part of the two polariton branches was clearly observed, the matter-like part was generally elusive. Our electromagnetic simulations quantitatively reproduce our observation for the upper-polariton branch. However, for the lower-polariton branch, our simulations predict a pronounced resonance, which was absent in experimental spectra. This discrepancy may be a consequence of the breakdown of the dipole approximation in this extreme confinement situation.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Inter-Site Distance Effect in Electrocatalysis

引用

Angewandte Chemie 2025年

作者： Jiongcan Xiang Pengfei Wang Panpan Li Min Zhou Guihua Yu Zhaoyu Jin Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 611731 China College of Materials Science and Engineering Sichuan University Chengdu 610065 China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China Materials Science and Engineering Program and Walker Department of Mechanical Engineering the University of Texas at Austin Austin TX 78712 USA

The inter-site distance effect (ISDE) has gained significant attention in heterogeneous catalysis, challenging classical models that treat adjacent nonbonded sites as isolated. Recent studies demonstrate that these sites can exhibit long-range cooperative interactions, enhancing reaction efficiencies. Fully leveraging the ISDE to overcome limitations in site reactivity requires a multidisciplinary approach and advanced techniques. This review provides a comprehensive overview of ISDE in electrocatalysis, starting with strategies for synthesizing materials with tunable inter-site distances. It examines ISDE across various catalyst models, including monometallic and heteronuclear atomic sites, active sites within clusters, and the lattice of nanocatalysts, focusing on their electronic structures, spatial geometries, and synergistic interactions. Advanced characterization and computational methods are highlighted as essential for identifying inter-site structures and distances, providing a systematic framework for understanding ISDE's role in electrocatalysis. The review also proposes best practices for studying ISDE, addressing current challenges and offering future perspectives. These insights aim to inform the design of highly efficient catalysts, enhance the understanding of catalytic mechanisms, and contribute to the development of more efficient energy conversion technologies, providing a foundation for further research into optimizing electrocatalysts.

关键词： Electrocatalysis Inter-site distance Single-atom catalysts Site density

来源：评论

学校读者我要写书评

暂无评论

Characterizing the mechanical response of metallic glasses to uniaxial tension using a spring network model

arXiv

引用

arXiv 2023年

作者： Nawano, Aya Schroers, Jan Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Metallic glasses are frequently used as structural materials. Therefore, it is important to develop methods to predict their mechanical response as a function of the microstructure prior to loading. We develop a novel coarse-grained spring network model, which describes the mechanical response of metallic glasses using an equivalent series network of springs, which can break and re-form to mimic atomic rearrangements during deformation. To validate the spring network model, we perform numerical simulations of quasistatic, uniaxial tensile deformation of Lennard-Jones and embedded atom method (EAM) potentials for Cu50Zr50 metallic glasses in the absence of large-scale shear band formation. We consider samples prepared using a wide range of cooling rates and with different amounts of crystalline order. We show that both the Lennard-Jones and EAM models possess qualitatively similar stress σ versus strain γ curves. By specifying five parameters in the spring network model (ultimate strength, strain at ultimate strength, slopes of σ(γ) at γ = 0 and at large strain, and strain at fracture where σ = 0), we can accurately describe the form of the stress-strain curves during uniaxial tension for the computational studies of Cu50Zr50, as well as recent experimental studies of several Zr-based metallic glasses. For the computational studies of Cu50Zr50, we find that the yield strain distribution is shifted to larger strains for slowly cooled glasses compared to rapidly cooled glasses. In addition, the average number of new springs and their rate of formation decreases with decreasing cooling rate. These effects offset each other at large strains, causing the stress-strain curve to become independent of the sample preparation protocol in this regime. In future studies, we will extract the parameters that define the spring network model directly from atomic rearrangements that occur during uniaxial deformation. © 2023, CC BY-NC-ND.

关键词： Metallic glass

来源：评论

学校读者我要写书评

暂无评论

Angle-resolved photoemission spectroscopy with an in situ tunable magnetic field

arXiv

引用

arXiv 2023年

作者： Huang, Jianwei Yue, Ziqin Baydin, Andrey Zhu, Hanyu Nojiri, Hiroyuki Kono, Junichiro He, Yu Yi, Ming Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley–Curl Institute Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Institute for Materials Research Tohoku University Katahira 2-1-1 Sendai980-8577 Japan Department of Applied Physics Yale University New HavenCT06511 United States

Angle-resolved photoemission spectroscopy (ARPES) is a powerful tool for probing the momentum-resolved single-particle spectral function of materials. Historically, in situ magnetic fields have been carefully avoided as they are detrimental to the control of photoelectron trajectory during the photoelectron detection process. However, magnetic field is an important experimental knob for both probing and tuning symmetry-breaking phases and electronic topology in quantum materials. In this paper, we introduce an easily implementable method for realizing an in situ tunable magnetic field at the sample position in an ARPES experiment and analyze magnetic field induced artifacts in ARPES data. Specifically, we identified and quantified three distinct extrinsic effects of a magnetic field: Constant energy contour rotation, emission angle contraction, and momentum broadening. We examined these effects in three prototypical quantum materials, i.e., a topological insulator (Bi2Se3), an iron-based superconductor (LiFeAs), and a cuprate superconductor (Pb-Bi2Sr2CuO6+x), and demonstrate the feasibility of ARPES measurements in the presence of a controllable magnetic field. Our studies lay the foundation for the future development of the technique and interpretation of ARPES measurements of field-tunable quantum phases. Copyright © 2023, The Authors. All rights reserved.

关键词： Photoelectrons

来源：评论

学校读者我要写书评

暂无评论

The connection between polymer collapse and the onset of jamming

arXiv

引用

arXiv 2023年

作者： Grigas, Alex T. Fisher, Aliza Shattuck, Mark D. O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that attractive systems quenched to temperatures below the glass transition T Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e. the number of contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymers are hypostatic at jamming onset, but effectively isostatic when including quartic modes. While attractive disk and polymer packings are hyperstatic, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g. scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static packings generated via attractive collapse or compression of repulsive particles possess similar structural and mechanical properties. © 2023, CC BY.

关键词： Amino acids

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：