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Topological Invariants of Metals and the Related Physical Effects

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Chinese physics Letters 2013年第2期30卷 178-181页

作者： ZHOU Jian-Hui JIANG Hua NIU Qian SHI Jun-Ren Beijing National Laboratory for Condensed Matter physics and Institute of physics Chinese Academy of SciencesBeijing 100190 International center for Quantum Materials Peking UniversityBeijing 100871 department of physics The University of TexasAustinTexas 78712-0264USA

The total reciprocal space magnetic flux threading through a closed Fermi surface is a topological invariant for a three-dimensional *** a Weyl metal,the invariant is nonzero for each of its Fermi *** show that such an invariant can be related to the magneto-valley-transport effect,in which an external magnetic field can induce a valley *** further show that a strain field can drive an electric current,and that the effect is dictated by a second-class Chern *** connections open the pathway to observe the hidden topological invariants in metallic systems.

关键词： invariant topological Fermi

Transport properties,upper critical field and anisotropy of Ba(Fe_(0.75)Ru_(0.25))_2As_2 single crystals

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Science China(physics,Mechanics & Astronomy) 2012年第12期55卷 2259-2263页

作者： XING Jie SHEN Bing ZENG Bin LIU JianZhong DING XiaXin WANG ZhiHe YANG Huan WEN HaiHu center for Superconducting physics and Materials National Laboratory of Solid State Mierostructures and Department of Physics Nanjing University Nanjing 210093 China National Laboratory for superconductivity Institute of Physics Chinese Academy of Sciences P.O.Box 603 Beijing 100190 China

The temperature and angle dependent resistivity of Ba(Fe 0.75 Ru 0.25) 2 As 2 single crystals were measured in magnetic fields up to 14 *** temperature dependent resistivity with the magnetic field aligned parallel to c-axis and ab-planes allow us to derive the slope of dH ab c2 /dT and dH c c2 /dT near T c yielding an anisotropy ratio Γ = dH ab c2 /dT/dH c c2 /dT ≈ *** scaling the curves of resistivity *** measured at a fixed temperature but different magnetic fields within the framework of the anisotropic Ginzburg-Landau theory,we obtained the anisotropy in an alternative *** we found that the anisotropy(m c /m ab) 1/2 was close to *** value is similar to that in Ba0.6K0.4Fe2As2(K-doped Ba122) and Ba(Fe 0.92 Co 0.08) 2 As 2(Co-doped Ba122).This suggests that the 3D warping effect of the Fermi surface in Ru-doped samples may not be stronger than that in the K-doped or Co-doped Ba122 samples,therefore the possible nodes appearing in Ru-doped samples cannot be ascribed to the 3D warping effect of the Fermi surface.

关键词： Ba(Fe 0.75 Ru 0.25) 2 As 2 transport properties anisotropy

A New Bipolar Type Transistor Created Based on Interface Effects of Integrated All Perovskite Oxides

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Chinese physics Letters 2012年第10期29卷 198-203页

作者： XIA Feng-Jin WU Hao FU Yue-Ju XU Bo YUAN Jie ZHU Bei-Yi QIU Xiang-Gang CAO Li-Xin LI Jun-Jie JIN Ai-Zi WANG Yu-Mei LI Fang-Hua LIU Bao-Ting XIE Zhong ZHAO Bai-Ru National Laboratory for superconductivity Institute of Physics and Center for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100190 School of physics and Microelectronic Science Hunan UniversityChangsha 410082 School of physics and Technology Wuhan UniversityWuhan 430072 College of physics Science and Technology Hebei UniversityBaoding 071002 department of Materials Science Wuhan University of Science and TechnologyWuhan 430081

Oxide transistor is the basic device to construct the oxide electronic circuit that is the backing to develop integrated oxide electronics with high efficiency and low power *** growing the perovskite oxide integrated layers and tailoring them to lead semiconducting functions at their interfaces,the development of oxide transistors may be able to *** realize a kind of p-i-n type integrated layers consisting of an n-type cuprate superconductor,p-type colossal magnetoresistance manganite,and a ferroelectric barrier(i).From this,bipolar transistors were fabricated at the back-to-back p-i-n junctions,for which the Schottky emission and p-n junction barriers,as well as the ferroelectric polarization,were integrated into the interfaces to control the transport properties;a preliminary but distinct current gain greater than 1.6 at input current of microampers order was *** results present a real possibility to date for developing bipolar all perovskite oxide transistors.

关键词： bipolar polarization ferroelectric

Effects of real-time traffic information systems on traffic performance under different network structures

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Journal of Central South University 2012年第2期19卷 586-592页

作者： YAO Xue-heng F.Benjamin ZHAN LU Yong-mei YANG Min-hua School of Geosciences and Info-physics Central South University texas center for Geographic Information Science Department of GeographyTexas State University-San Marcos

The effects of real-time traffic information system(RTTIS)on traffic performance under parallel,grid and ring networks were *** simulation results show that the effects of the proportion of RTTIS usage depend on the road network *** traffic on a parallel network,the performance of groups with and without RTTIS level is improved when the proportion of vehicles using RTTIS is greater than 0 and less than 30%,and a proportion of RTTIS usage higher than 90%would actually deteriorate the *** both grid and ring networks,a higher proportion of RTTIS usage always improves the performance of groups with and without *** all three network structures,vehicles without RTTIS benefit from some proportion of RTTIS usage in a system.

关键词： real-time traffic information traffic network traffic efficiency optimization of urban traffic

单层NbF4:一种跟铜氧高温超导体相类似的4d1化合物(英文)

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Science Bulletin 2020年第22期65卷 1901-1906页

作者：杨阳王万胜丁秦生王强华 texas center for superconductivity and department of physics University of Houston College of physics and Electronic Engineering Zhengzhou University of Light Industry department of physics Ningbo University National Laboratory of Solid State Microstructures & School of physics Nanjing University Collaborative Innovation center of Advanced Microstructures Nanjing University

密度泛函(DFT)以及奇异模泛函重整化群(SMFRG)等结果显示单层NbF4可能是4d1电子构型的铜氧高温超导体类似化合物,可以预想它也可以实现非常规超导.单层NbF4具有同铜氧面相类似的晶体结构. DFT结果显示单层NbF4具有4d1电子构型,即单个电... 详细信息

密度泛函(DFT)以及奇异模泛函重整化群(SMFRG)等结果显示单层NbF4可能是4d1电子构型的铜氧高温超导体类似化合物,可以预想它也可以实现非常规超导.单层NbF4具有同铜氧面相类似的晶体结构. DFT结果显示单层NbF4具有4d1电子构型,即单个电子位于Nb-4dxy轨道上.类比于铜氧化物,单个能带穿过费米能级形成类似四方形的费米面结构.基于Nb-4dxy的单轨道紧束缚模型, SMFRG计算分析了电子相互作用下体系的磁有序及超导现象.结果显示在半满(电子占据数n=1.0)时,体系最终(π,π)自旋密度波通道发散,意味此时体系形成G类型反铁磁序,正好与密度泛函的结果一致.在偏离半满时,体系超导通道最终发散,其超导配对对称性显示为d波超导.单层NbF4的磁性及超导性质跟铜氧化物相似,这是由相似的晶体及电子结构导致的结果.

关键词： Cuprates Two-dimensional superconductors d-wave pairing Electronic structure calculations

Anomalous Josephson current in quantum anomalous Hall insulator-based superconducting junctions with a domain wall structure

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Chinese physics B 2020年第9期29卷 487-497页

作者： Qing Yan Yan-Feng Zhou Qing-Feng Sun International center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Collaborative Innovation center of Quantum Matter Beijing 100871China department of physics University of Texas at DallasRichardsonTexas 75080USA CAS center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We theoretically study the Josephson effect in a quantum anomalous Hall insulator(QAHI)nanoribbon with a domain wall structure and covered by the *** anomalous Josephson current,the nonzero supercurrent at the zero superconducting phase difference,appears with the nonzero magnetization and the suitable azimuth angle of the domain *** on the configuration of the domain wall,the anomalous current peaks in the Bloch type but disappears in the Néel type because the y-component of magnetization is necessary to break symmetry to arouse the anomalous *** phase shift of the anomalous current is tunable by the magnetization,the azimuth angle,or the thickness of the domain *** introducing a bare QAHI region in the middle of the junction which is not covered by the superconductor,the anomalous Josephson effect is enhanced such that the phase shift can exceedπ.Thus,a continuous change between 0 andπjunctions is realized via regulating the configuration of the domain wall or the magnetization *** long as an s-wave superconductor is placed on the top of the QAHI with a domain wall structure,this proposal can be experimentally fabricated and useful for the phase battery or superconducting quantum bit.

关键词： anomalous Josephson current quantum anomalous Hall insulator domain wall Josephson junction

A Study of Surface Modification of Poly(lactic-co-glycolic) Acid Using Argon Ion Irradiation

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Journal of Surface Engineered Materials and Advanced Technology 2014年第6期4卷 326-331页

作者： Ananta Raj Adhikari Buddhi Prasanga Tilakaratne Dharshana Wijesundera Wei-Kan Chu texas center for superconductivity University of Houston Houston USA department of physics University of Houston Houston USA

The effect of Argon ion irradiation to the surface properties of poly(lactic-co-glycolic) acid (PLGA) was studied. A beam of 170 keV Argon ions was implanted at different fluencies (1 × 1012, 1 × 1013, 1 × 1014, and 1 × 1015 ions/cm2). X-ray photoelectron spectroscopy (XPS) was used to analyze the evolution of the bonding microstructure of PLGA due to irradiation. Surface morphology was monitored using atomic force microscopy (AFM). AFM analysis shows that film roughness increased to maximum at the dose of 1 × 1014 ions/cm2 where the formations of hillocks were also detected. Hydrophilicity of PLGA is important for their applications in biomedicine such as bioscaffolds. Hydrophilicity was monitored using water contact angle measurements for both unmodified and ion-modified PLGA. It was observed that hydrophilicity of PLGA changes with the ion irradiation. This demonstrates that ion irradiation can be an alternative approach to control hydrophilicity of PLGA. PLGA scaffolds modified with ion irradiation could therefore be more suitable for the biomedical applications.

关键词： Poly(lactic-co-glycolic) Acid Scaffold Surface Modification Ion Irradiation

The ALMA-QUARKS Survey.Ⅱ.The ACA 1.3 mm Continuum Source Catalog and the Assembly of Dense Gas in Massive Star-Forming Clumps

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Research in Astronomy and Astrophysics 2024年第6期24卷 119-139页

作者：许峰玮 Ke Wang Tie Liu Lei Zhu Guido Garay Xunchuan Liu Paul Goldsmith Qizhou Zhang Patricio Sanhueza Shengli Qin Jinhua He Mika Juvela Anandmayee Tej Hongli Liu Shanghuo Li Kaho Morii Siju Zhang Jianwen Zhou Amelia Stutz Neal JEvans Kee-Tae Kim Shengyuan Liu Diego Mardones Guangxing Li Leonardo Bronfman Ken’ichi Tatematsu Chang Won Lee Xing Lu Xiaofeng Mai Sihan Jiao James O.Chibueze Keyun Su Viktor L.Tóth Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Chinese Academy of Sciences South America center for Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Departamento de Astronomía Universidad de ChileLas Condes7591245 SantiagoChile Jet Propulsion Laboratory California Institute of Technology4800 Oak Grove DrivePasadena CA 91109USA center for Astrophysics|Harvard&Smithsonian 60 Garden StreetCambridgeMA 02138USA National Astronomical Observatory of Japan National Institutes of Natural Sciences2-21-1 OsawaMitakaTokyo 181-8588Japan Astronomical Science Program The Graduate University for Advanced StudiesSOKENDAI2-21-1 OsawaMitakaTokyo 181-8588Japan School of physics and Astronomy Yunnan UniversityKunming 650091China Yunnan Observatories Chinese Academy of SciencesKunming 650216China department of physics University of HelsinkiPO Box 64FI-00014 HelsinkiFinland Indian Institute of Space Science and Technology Thiruvananthapuram 695547KeralaIndia Max Planck Institute for Astronomy Königstuhl 17D-69117 HeidelbergGermany department of Astronomy Graduate School of ScienceThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-0033Japan Max-Planck-Institut für Radioastronomie Auf dem Hügel 6953121 BonnGermany Departamento de AstronomÂıa Universidad de ConcepcionCasilla 160-CConcepci onChile department of Astronomy The University of Texas at AustinTexas 78712-1205USA Korea Astronomy and Space Science Institute 776 Daedeokdae-roYuseong-guDaejeon 34055Republic of Korea Institute of Astronomy and Astrophysics Academia SinicaRoosevelt RoadTaipei 10617TaiwanChina South-Western Institute for Astronomy Research Yunnan UniversityKunming 650091China Korea Astronomy and Space Science Institute 776 Daedeok-daeroYuseong-guDaejeon 34055Republic of

Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”,is observing 139 massive starforming clumps at ALMA Band 6(λ~1.3 mm).This paper introduces the Atacama Compact Array(ACA)7 m data of the QUARKS survey,describing the ACA observations and data *** multiwavelength data,we provide the first edition of QUARKS atlas,offering insights into the multiscale and multiphase interstellar medium in high-mass star *** ACA 1.3 mm catalog includes 207 continuum sources that are called ACA *** gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model,and the mass and density are derived from a dust emission *** ACA sources are massive(16–84 percentile values of 6–160 M_(⊙)),gravity-dominated(M∝R^(1.1))fragments within massive clumps,with supersonic turbulence(M>1)and embedded star-forming *** find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6%between the *** considering fragments as representative of dense gas,the ratio indicates a dense gas fraction(DGF)of 6%,although with a wide scatter ranging from 1%to 10%.If we consider the QUARKS massive clumps to be what is observed at various scales,then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster *** the ACA data over four orders of magnitude of luminosity-to-mass ratio(L/M),we find that the DGF increases significantly with L/M,which indicates clump evolutionary *** observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.

关键词： stars:formation ISM:kinematics and dynamics ISM:clouds stars:protostars

Theoretical Prediction of superconductivity in Boron Kagome Monolayer:MB3(M=Be,Ca,Sr)and the Hydrogenated CaB3

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Chinese physics Letters 2023年第1期40卷 53-59页

作者：杨柳李牙平刘浩东焦娜倪美燕路洪艳张平 C.S.Ting School of physics and Physical Engineering Qufu Normal UniversityQufu 273165China Institute of Applied physics and Computational Mathematics Beijing 100088China texas center for superconductivity and department of physics University of HoustonHoustonTexas 77204USA

Using first-principles calculations, we predict a new type of two-dimensional(2D) boride MB3(M = Be,Ca, Sr), constituted by boron kagome monolayer and the metal atoms adsorbed above the center of the boron hexagons. The band structures show that the three MB3compounds are metallic, thus the possible phononmediated superconductivity is explored. Based on the Eliashberg equation, for BeB3, CaB3, and SrB3, the calculated electron–phonon coupling constants λ are 0.46, 1.09, and 1.33, and the corresponding superconducting transition temperatures Tc are 3.2, 22.4, and 20.9 K, respectively. To explore superconductivity with higher transition temperature, hydrogenation and charge doping are further considered. The hydrogenated CaB3, i.e.,HCaB3, is stable, with the enhanced λ of 1.39 and a higher Tc of 39.3 K. Moreover, with further hole doping at the concentration of 5.8 × 1011hole/cm2, the Tc of HCaB3can be further increased to 44.2 K, exceeding the Mc Millan limit. The predicted MB3and HCaB3provide new platforms for investigating 2D superconductivity in boron kagome lattice since superconductivity based on monolayer boron kagome lattice has not been studied before.

关键词： boron doping superconductivity