检索结果-内蒙古大学图书馆

Robust wavefront dislocations of Friedel oscillations in gapped graphene

Physical Review B 2021年第16期103卷 L161407-L161407页

作者： Shu-Hui Zhang Jin Yang Ding-Fu Shao Zhenhua Wu Wen Yang College of Mathematics and Physics Beijing University of Chemical Technology Beijing 100029 China Beijing Computational Science Research Center Beijing 100193 China Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience University of Nebraska–Lincoln Lincoln Nebraska 68588-0299 USA Key Laboratory of Microelectronics Devices and Integrated Technology Institute of Microelectronics of Chinese Academy of Sciences Beijing 100029 China

Friedel oscillation is a well-known wave phenomenon which represents the oscillatory response of electron waves to imperfection. By utilizing the pseudospin-momentum locking in gapless graphene, two recent experiments demonstrate the measurement of the topological Berry phase by corresponding to the unique number of wavefront dislocations in Friedel oscillations. Here, we study the Friedel oscillations in gapped graphene, in which the pseudospin-momentum locking is broken. Unusually, the wavefront dislocations do occur like that in gapless graphene, which requires immediate verification in the current experimental condition. The number of wavefront dislocations is ascribed to the invariant pseudospin winding number in gapped and gapless graphene. This study deepens the understanding of the correspondence between topological quantity and wavefront dislocations in Friedel oscillations and implies the possibility to observe the wavefront dislocations of Friedel oscillations in intrinsic gapped two-dimensional materials, e.g., transition metal dichalcogenides.

关键词： Geometric & topological phases Graphene Green's function methods

来源：评论

学校读者我要写书评

暂无评论

Emergence of high-temperature superconducting phase in the pressurized La3Ni2O7 crystals

arXiv

引用

arXiv 2023年

作者： Hou, J. Yang, P.T. Liu, Z.Y. Li, J.Y. Shan, P.F. Ma, L. Wang, G. Wang, N.N. Guo, H.Z. Sun, J.P. Uwatoko, Y. Wang, M. Zhang, G.-M. Wang, B.S. Cheng, J.-G. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100190 China Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices School of Physics Sun Yat-Sen University Guangdong Guangzhou510275 China Key Laboratory of Materials Physics Ministry of Education School of Physics and Microelectronics Zhengzhou University Zhengzhou450052 China Institute of Quantum Materials and Physics Henan Academy of Sciences Zhengzhou450046 China Institute for Solid State Physics University of Tokyo Chiba Kashiwa277-8581 Japan State Key Laboratory for Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China

The recent report of pressure-induced structure transition and signature of superconductivity with Tc ≈ 80 K above 14 GPa in the La3Ni2O7 crystals has garnered considerable attention. To further elaborate this discovery, we carried out comprehensive resistance measurements on the La3Ni2O7 crystals grown with the optical-image floating zone furnace under oxygen pressure (15 bar) by using the diamond anvil cell (DAC) and cubic anvil cell (CAC), which employs the solid (KBr) and liquid (Glycerol) pressure transmitting medium, respectively. For the sample #1 measured in DAC, it exhibits a semiconducting-like behavior with large resistance at low pressures and becomes metallic gradually upon compression. At the pressures P ≥ 13.7 GPa, we observed the appearance of resistance drop as large as ~50% around 70 K, which evolves into a kink-like anomaly at pressures above 40 GPa and shifts to lower temperatures gradually with increasing magnetic field. These observations are consistent with the recent report mentioned above. On the other hand, the sample #2 measured in CAC retains the metallic behavior in the investigated pressure range up to 15 GPa. The hump-like anomaly in resistance around ~130 K at ambient pressure disappears at P ≥ 2 GPa. In the pressure range from 11 GPa to 15 GPa, we observed the gradual development of a shoulder-like anomaly in resistance at low temperatures, which evolves into a pronounced drop of resistance by 98% below 62 K at 15 GPa, reaching a temperature-independent resistance of 20 μΩ below 20 K. Similarly, this resistance anomaly can be shifted to lower temperatures progressively by applying external magnetic fields, resembling a typical superconducting transition. Measurements on sample #3 in CAC reproduce the resistance drop at pressures above 10 GPa and realize the zero resistance below 10 K at 15 GPa even though an unusual semiconducting-like behavior retains in the normal state. Based on these results, we discussed some issues regarding th

关键词： Lanthanum compounds

来源：评论

学校读者我要写书评

暂无评论

Efficient Second-Harmonic Generation from silicon Slotted Nanocubes with Bound States in the Continuum

arXiv

引用

arXiv 2022年

作者： Fang, Cizhe Yang, Qiyu Yuan, Qingchen Gu, Linpeng Gan, Xuetao Shao, Yao Liu, Yan Han, Genquan Hao, Yue Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory School of Microelectronics Xidian University Xi’an710071 China Key Laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information Technology Shaanxi Key Laboratory of Optical Information Technology School of Physical Science and Technology Northwestern Polytechnical University Xi’an710129 China Shanghai Energy Internet Research Institute of State Grid 251 Libing Road Pudong New Area Shanghai201210 China The Research Center for Intelligent Chips and Devices Zhejiang Lab Hangzhou311121 China

Optical materials with centrosymmetry, such as silicon and germanium, are unfortunately absent of second-order nonlinear optical responses, hindering their developments in efficient nonlinear optical devices. Here, a design with an array of slotted nanocubes is proposed to realize remarkable second harmonic generation (SHG) from the centrosymmetric silicon, which takes advantage of enlarged surface second-order nonlinearity, strengthened electric field over the surface of the air-slot, as well as the resonance enhancement by the bound states in the continuum. Compared with that from the array of silicon nanocubes without air-slots, SHG from the slotted nanocube array is improved by more than two orders of magnitude. The experimentally measured SHG efficiency of the silicon slotted nanocube array is high as 1.8×10−4 W−1, which is expected to be further engineered by modifying the air-slot geometries. Our result could provide a new strategy to expand nonlinear optical effects and devices of centrosymmetric materials. Copyright © 2022, The Authors. All rights reserved.

关键词： silicon

来源：评论

学校读者我要写书评

暂无评论

Emergence of high-temperature superconductivity at the interface of two Mott insulators

引用

Physical Review B 2022年第2期105卷 024516-024516页

作者： Lele Ju Tianshuang Ren Zhu Li Zhongran Liu Chuanyu Shi Yuan Liu Siyuan Hong Jie Wu He Tian Yi Zhou Yanwu Xie Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation and Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou 310027 China Center of Electron Microscope State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Key Laboratory for Quantum Materials of Zhejiang Province School of Science Westlake University Hangzhou 310024 China Institute of Natural Sciences Westlake Institute for Advanced Study Hangzhou 310024 China School of Physics and Microelectronics Zhengzhou University Zhengzhou 450052 China Beijing National Laboratory for Condensed Matter Physics & Institute of Physics Chinese Academy of Sciences Beijing 100190 China Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China

Interfacial superconductivity has manifested itself in various types of heterostructures: band insulator–band insulator, band insulator–Mott insulator, and Mott insulator–metal. We report the observation of high-temperature superconductivity (HTS) in a complementary and long-expected type of heterostructures, which consists of two Mott insulators, La2CuO4 (LCO) and PrBa2Cu3O7 (PBCO). By carefully controlling oxidization condition and selectively doping CuO2 planes with Fe atoms, which suppress superconductivity, we found that the superconductivity arises at the LCO side and is confined within no more than two unit cells (∼2.6 nm) near the interface. A phenomenon of “overcome the Fe barrier” will show up if excess oxygen is present during growth. Some possible mechanisms for the interfacial HTS have been discussed, and we attribute HTS to the redistribution of oxygen.

关键词： Impurities in superconductors Mott-superfluid transition Superconducting phase transition Cuprates Heterostructures Interfaces Thin films Film deposition

来源：评论

学校读者我要写书评

暂无评论

The Quantizable Contribution of Epdd, Sblc, and Iblc Effects to Colossal Permittivity in La-Doped Batio3 Ceramic

SSRN

引用

SSRN 2022年

作者： Meng, Yingzhi Liu, Kang Lei, Xiuyun Li, Chunchun Yang, Zhao Wang, Dawei Zhang, Qi Zhang, Hongfang Yan, Shiguang Chen, Jun Liu, Laijun Key Laboratory of Nonferrous Materials and New Processing Technology Ministry of Education Guilin University of Technology Guilin541004 China Guangxi Key Lab of Optical and Electronic Functional Materials and Devices Guilin University of Technology Guilin541004 China College of Materials Science and Engineering Guilin University of Technology Guilin541004 China State Key Laboratory of Advanced Materials and Electronic Components Guangdong Fenghua Advanced Technology Holding Co. Ltd. Zhaoqing526060 China School of Microelectronics State Key Laboratory for Mechanical Behaviour of Materials Xi’an Jiaotong University Xi’an China BC Materials Basque Center for Materials Application & Nanostructures Basque Spain School of Physical Science and Technology Suzhou University of Science and Technology Suzhou215009 China Key Laboratory of Inorganic Functional Materials and Devices Shanghai Institute of Ceramics Chinese Academy of Sciences 1295 Dingxi Road Shanghai200050 China Beijing Advanced Innovation Center for Materials Genome Engineering Department of Physical Chemistry University of Science and Technology Beijing Beijing100083 China

关键词： Capacitance

来源：评论

学校读者我要写书评

暂无评论

Ferroelectric structural transition in hafnium oxide induced by charged oxygen vacancies

引用

Physical Review B 2021年第18期104卷 L180102-L180102页

作者： Ri He Hongyu Wu Shi Liu Houfang Liu Zhicheng Zhong Key Laboratory of Magnetic Materials Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China School of Science Westlake University Hangzhou Zhejiang 310024 China Institute of Natural Sciences Westlake Institute for Advanced Study Hangzhou Zhejiang 310024 China and Key Laboratory for Quantum Materials of Zhejiang Province Hangzhou Zhejiang 310024 China Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China

The discovery of ferroelectric HfO2 in thin films and more recently in bulk is an important breakthrough because of its silicon compatibility and unexpectedly persistent polarization at low dimensions, but the origin of its ferroelectricity is still under debate. The stabilization of the metastable polar orthorhombic phase was often considered as the cumulative result of various extrinsic factors such as stress, grain boundary, and oxygen vacancies as well as phase transition kinetics during the annealing process. We propose a mechanism to stabilize the polar orthorhombic phase over the nonpolar monoclinic phase that is the bulk ground state. Our first-principles calculations demonstrate that the doubly positively charged oxygen vacancy, an overlooked defect but commonly presenting in binary oxides, is critical for the stabilization of the ferroelectric phase. The charge state of the oxygen vacancy serves as a degree of freedom to control the thermodynamic stability of competing phases of wide band gap oxides.

关键词： Ferroelectricity Point defects Oxides Density functional theory

来源：评论

学校读者我要写书评

暂无评论

Structural phase transition of monochalcogenides investigated with machine learning

引用

Physical Review B 2022年第9期105卷 094116-094116页

作者： J. Zhang F. Zhang D. Wei L. Liu X. Liu D. Fang G. X. Zhang X. Chen D. Wang School of Microelectronics & State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China Key Lab of Micro-Nano Electronics and System Integration of Xi'an City Xi'an Jiaotong University Xi'an 710049 China Guangxi Key Laboratory of Optical and Electronic Materials and Devices College of Materials Science and Engineering Guilin University of Technology Guilin 541004 China Engineering Research Center of Nanoelectronic Integration and Advanced Equipment Ministry of Education School of Physics and Electronic Science East China Normal University Shanghai 200062 China MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter School of Physics Xi' an Jiaotong University Xi'an 710049 China School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 China Department of Applied Physics Aalto University Espoo 00076 Finland

As machine learning becomes increasingly important in science and engineering, it holds the promise to provide a universal approach applicable to various systems to investigate their crystalline phase transitions. Here, we build and train accurate artificial neural networks that can distinguish tiny energy difference, which is crucial to predict the crystalline phase transitions. Employing the trained artificial neural networks in Monte Carlo simulations as the surrogate energy function, we apply this approach to monochalcogenides, including bulk and two-dimensional monolayer SnTe and GeTe, investigating their crystalline phase transitions. The machine-learning approach, when viewed as providing a universal mathematical structure, can be transferred to the investigation of other materials when the training data set generated with ab initio methods are available. Moreover, the machine-learning approach resolves the difficulties associated with constructing the effective Hamiltonian for monochalcogenides, showing great potential with its accuracy and efficiency.

关键词： Ferroelectricity Structural phase transition Chalcogenides Machine learning

来源：评论

学校读者我要写书评

暂无评论

Posture Recognition Based on the Improved Optical Diffractive Neural Network 3

Posture Recognition Based on the Improved Optical Diffractiv...

引用

3rd IEEE International Conference on Electronic Information and Communication technology, ICEICT 2020

作者： Zhang, Hongyi Shui, Shan Wu, Yuwen Yang, Qiang Cai, Yijun School of Opto-electronic and Communication Engineering Xiamen University of Technology Xiamen361024 China College of Communication and Information Engineering Xi'an University of Science and Technology Xi'an710054 China Key Laboratory of Microelectronic Devices Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing100191 China

ISBN: (纸本)9781728190457

Optical computing has significant advantages in power consumption efficiency and computing speed. As an optical machine learning framework, diffractive optical neural networks have achieved good results in the application of feature detection and target classification. This paper introduces an optical neural network structure-express wavenet, which has a random shift wavelet pattern and a highway structure, which can greatly reduce the parameters generated in the modulation process of light and solve the problem of gradient disappearance during network training. The classification rate of express wavenet network for the 4 types of different posture and action image data sets reached 87.96%, which is a greater improvement than the 77.8% recognition rate of the diffraction deep neural network D2NN. © 2020 IEEE.

关键词： Image classification

来源：评论

学校读者我要写书评

暂无评论

Tunable synaptic devices based on ambipolar MoTe2 transistor

Tunable synaptic devices based on ambipolar MoTe2 transistor

引用

IEEE Electron devices technology and Manufacturing Conference (EDTM)

作者： Tingting Gao Xuefei Li Linxin Han Yanqing Wu Wuhan National High Magnetic Field Center and School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan China Institute of Microelectronics and Key Laboratory of Microelectronic Devices and Circuits (MOE) Peking University Beijing China

Synapse is one of the main elements of hardware implementation in a neuron network. Complex CMOS technology-based circuits using various Si-based transistors, non-Si based memory devices like RRAM, and 2D FET devices serve as hardware implement for neuron network. In this work, we demonstrate ambipolar MoTe₂ FET devices with a wide range oftunability in synaptic characteristic and classical paired pulsed facilitation as well as spike-timing-dependent plasticity function.

关键词： Neurons Field effect transistors CMOS technology Hardware Biology Manufacturing Synapses

来源：评论

学校读者我要写书评

暂无评论

Bulk superconductivity and Pauli paramagnetism in nearly stoichiometric CuCo2S4

引用

Physical Review Materials 2021年第7期5卷 074804-074804页

作者： Yu-Ying Jin Shi-Huai Sun Yan-Wei Cui Qin-Qing Zhu Liang-Wen Ji Zhi Ren Guang-Han Cao Department of Physics Zhejiang Province Key Laboratory of Quantum Technology and Devices Interdisciplinary Center for Quantum Information and State Key Lab of Silicon Materials Zhejiang University Hangzhou 310027 China School of Science Westlake Institute for Advanced Study Westlake University Hangzhou 310064 China Collaborative Innovation Centre of Advanced Microstructures Nanjing University Nanjing 210093 China

It has long remained elusive whether CuCo2S4 thiospinel shows bulk superconductivity (SC). Here we clarify the issue by studying the samples of sulfur-deficient CuCo2S3.7 and sulfurized CuCo2S4. The sample CuCo2S3.7 has a smaller lattice constant of a=9.454 Å, and it is not superconducting down to 1.8 K. After a full sulfurization, the a axis of the thiospinel phase increases to 9.475 Å, and the thiospinel becomes nearly stoichiometric CuCo2S4, although a secondary phase of slightly Cu-doped CoS2 forms. Bulk SC at 4.2 K and Pauli paramagnetism have been demonstrated for the sulfurized CuCo2S4 by the measurements of electrical resistivity, magnetic susceptibility, and specific heat.

关键词： Magnetism Specific heat Superconductivity Inorganic compounds Spinels Superconductors Chemical synthesis

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：