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Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

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Science China(physics,Mechanics & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2. ZHOU Yueliang2. LIU Zhen2. WANG Shufang2. CHEN Zhenghao2. L?Huibin2. YANG Guozhen2. XIAO Ling3. REN Hongtao3. JIAO Yulei3.& ZHENG Minghui3.1. Department of physics, College of Science, beijing Jiaotong University, beijing 100044, China 2. Laboratory of Optical physics, Institute of physics and {13. for condensed matter physics, chinese academy of sciences, beijing 100080, China 3. General Research Institute for Nonferrous Metals, beijing 100088, China Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) Department of physics College of Science Beijing Jiaotong University Beijing China Laboratory of Optical physics Institute of physics and{2. for {3. matter physics Chinese Academy of Sciences Beijing China General Research Institute for Nonferrous Metals Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2.aCuO5 (Y2.1) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y2.1 powder is added to the YBa2.u3.7–5 (Y12.) powder,J c for the superconducting thick film by approaches described above reaches 7.008×103.A/cm2.(77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

Research progress in the inner surface modification of metal tubes by plasma processing

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Progress in Natural Science:Materials International 2006年第11期16卷 1119-1126页

作者： ZHANG Guling~ 1,2.**, WU Xingfang~1, GU Weichao~2. CHEN Guangliang~2. FENG Wenran~2. NIU Erwu~2. LI Li~2. L Guohua~2. CHEN Huan~2. FAN Songhua~2. LIU Chizi~2.and YANG Size~2.1. School of Material Science and Engineering, University of Science and Technology beijing, beijing 100083. China 2. beijing National Laboratory for condensed matter physics, Institute of physics, chinese academy of sciences, beijing 100080, China) School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China beijing National Laboratory for condensed{2. {3. Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The recent progress in inner surface hardening of tubes by plasma processing is summerized. Several techniques of inner surface plasma source ion implantation and deposition are introduced, and their advantages and disadvantages are discussed. The basic principles, technical features and new progress of inner surface plasma source ion implantation methods for metal tubes, which were developed in our laboratory, are described in detail. And perspectives of the future technical development for inner surface ion implantation of tubes are presented.

关键词： PSII metal tubes inner surface surface modification.

Model for Unidirectional Movement of Axonemal and Cytoplasmic Dynein Molecules

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Acta Biochimica et Biophysica Sinica 2006年第10期38卷 711-724页

作者： Ping XIE* Shuo-Xing DOU Peng-Ye WANG Laboratory of Soft matter physics,{2. National Laboratory for {3. matter physics,Institute of physics,chinese academy of sciences,{2. 100080,China Laboratory of Soft matter physics Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of SciencesBeijing 100080 China

A model for the unidirectional movement of dynein is presented based on the structuralobservations and biochemical experimental results *** this model,the binding affinity of dynein formicrotubule (MT) is independent of its nucleotide state and the change between strong and weak MT-bindingis determined naturally by the variation of relative orientation between the stalk and MT,as the stalk rotatesfollowing nucleotide-state *** the enigmatic communication from the adenosine triphosphate(ATP)-binding site in the globular domain to the far MT-binding site in the tip of the stalk,which is aprerequisite in conventional models,is not *** the present model,the previous experimentalresults such as the effect of ATP and adenosine diphosphate (ADP) bindings on dissociation of dynein fromMT,the movement of single-headed axonemal dyneins at saturating ATP concentration,the load dependenceof step-size for the movement of two-headed cytoplasmic dyneins and the dependence of stall force on ATPconcentration can be well explained.

关键词： dynein mechanism mechanochemistry molecular motor

The size effect on transport properties of colossal magnetoresistance materials La_(0.67)Ca_(0.3.)MnO_3

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Science China(physics,Mechanics & Astronomy) 2008年第3期51卷 251-257页

作者： LI PeiGang1,2.LEI Ming1,2.GUO YanFeng2.GUO Xi2.CHEN LeiMing2. TANG WeiHua1,2.SONG PengYun3.& CHEN JinPing3.1 Department of physics,center for Optoelectronics Materials and Devices,Zhejiang Sci-Tech University,Hangzhou 3.0018,China 2.National Laboratory for{2. matter physics,Institute of physics,{13. academy of sciences,beijing 100080,China 3.Department of physics,Peking University,beijing 100875,China Department of physics Center for Optoelectronics Materials and Devices Zhejiang Sci-Tech University Hangzhou China National Laboratory for condensed matter{2. Institute of Physics Chinese Academy of Sciences Beijing China Department of physics Peking University Beijing China

High quality La0.67Ca0.3.MnO3.(LCMO) film was deposited via a novel pulsed electron deposition technique on SrTiO3.100) single crystal substrate. The micro-bridge with different widths was fabricated by using electron beam lithography (EBL) technique and their transport properties were studied. For the micro-bridges with width of 2.and 1.5 μm,the insulator-to-metal transition temperature (TP) keeps un-changed compared with the film. For the micro-bridges with width of 1 μm,the TP shifts towards the lower temperature by 50 K. When the width decreases down to 500 nm,the insulator-to-metal transition disappears. The magnetoresistance be-havior of these micro-bridges was studied,and the results show that the low field magnetoresistance (LFMR) decreases and the high field magnetoresistances (HFMR) keep almost unchanged as the width of micro-bridge is reduced.

关键词： colossal magnetoresistance pulsed electron deposition electron beam lithography electrical transport properties

An Explicit Function Expression for dc Bias and Temperature Dependence of Magnetoresistances in Magnetic Tunnel Junctions

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Journal of Materials Science & Technology 2002年第6期18卷 497-501页

作者： Xiufeng HANState Key Laboratory of Magnetism, Institute of physics and center of{2. {3. physics, chinese academy of sciences, beijing 100080, China chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China chinese Acad Sci Ctr Condensed Matter Phys Beijing 100080 Peoples R China

An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2.|TJ|2.) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe2.(2. nm)/lr2.Mn78(12.nm)/Co75Fe2.(4 nm)/AI(0.8 nm)-oxide/Co75Fe2.(4 nm)/Ni79Fe2.(2. nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.

关键词： Magnetic tunnel junction TMR Spin-electron transport Magnon excitation Spin-polarization Magnetotransport

Oxygen pressure dependent electro-resistance in La_(0.9)Sr_(0.1)MnO_3.thin films grown by laser molecular beam epitaxy

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Science China(physics,Mechanics & Astronomy) 2008年第3期51卷 232-236页

作者： OUYANG SiHua1,2.WANG ChunChang2.LIU GuoZhen2.HE Meng2. JIN KuiJuan2.DANG ZhiMin1 & L HuiBin2. College of Materials Science and Engineering,beijing University of Chemical Technology,beijing 10002.,China 2.beijing National Laboratory for condensed matter {13.,Institute of {13.,chinese academy of sciences,beijing 100080,China College of Materials Science and Engineering Beijing University of Chemical Technology Beijing China beijing National Laboratory for condensed{2. {3. Institute of Physics Chinese Academy of Sciences Beijing China

We report here studies on the influence of oxygen pressure on the electroresis-tance behavior of La0.9Sr0.1MnO3.thin films fabricated by laser molecular beam epi-taxy. It was found that the film deposited at lower oxygen pressure shows larger c-axis parameter,higher resistance,and more distinct electroresistance. These results reveal that the electroresistance of manganite thin films can be tuned by the conditions of film fabrication.

关键词： La0.9Sr0.1MnO3 thin film electroresistance effect laser molecular beam epitaxy

Anomalous Hall effect in perpendicular CoFeB thin films

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chinese physics B 2014年第4期23卷 9-17页

作者：朱涛 Institute of physics and beijing National Laboratory for{2. {3. physics Chinese Academy of Sciences

Our recent research achievements in the perpendicular magnetic anisotropy （PMA） properties of the CoFeB sand- wiched by MgO and tantalum layers are summarized. We found that the PMA behaviors of Ta/CoFeB/MgO and MgO/CoFeB/Ta thin films are different. The larger PMA in the latter film is related to the lower magnetization of CoFeB deposited on MgO. Furthermore, we have demonstrated a large anomalous Hall effect in perpendicular CoFeB thin fihn. Our results show large anomalous Hall resistivity, large longitudinal resistivity, and low switching field can be achieved, all at the same time, in the perpendicular CoFeB thin film. Anomalous Hall effect with high and linear sensitivity is also found in an MgO/CoFeBFFa thin film with a thick MgO layer, which opens a door tbr future device applications of perpendicular ferromagnetic thin films.

关键词： anomalous Hall effect perpendicular magnetic anisotropy magnetic properties of interfaces

Fluorescence dynamics of interactions between polyamide PyPyPyβDp and DNA

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Science China Chemistry 2006年第1期49卷 75-80页

作者： ZHANG Huijuan1,2. WANG Jin3. WU Yishi1, YUAN Gu3. AI Xicheng1, WANG Li4 & ZHANG Jianping1 1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, chinese academy of sciences, beijing 100080, China 2. School of Life Science and Technology,{2. Institute of Technology,{2. 100081, China 3. College of Chemistry and Molecular Engineering, Peking University, beijing 100080, China 4. center for condensed matter physics, Institute of physics, chinese academy of sciences, beijing 100080, China Correspondence should be addressed to Ai Xicheng and Zhang Jianping State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing China School of Life Science and Technology Beijing Institute of Technology Beijing China College of Chemistry and Molecular Engineering Peking University Beijing China center for condensed{2. {3. Institute of Physics Chinese Academy of Sciences Beijing China

The photophysical properties of the polyamide PyPyPyβDp (PPP) were investigated by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. It was found that the excited-state properties of PPP are very sensitive to solvents. In TKMC buffer PPP exhibited weak fluorescence with a decay time constant of 16 ps, while with the decrease of the solvent polarity PPP showed the blue-shifted peak position, increased inten-sity and lengthened life-time for its fluorescence behavior. In the presence of calf thymus DNA, it was observed that the fluorescence intensity was enhanced and the fluorescence lifetime increased from 16 to 3.0}ps for PPP, which verified that PPP bound into the minor groove of DNA duplex.

关键词： polyamide (PPP), calf thymus DNA (ctDNA), time-resolved fluorescence spectroscopy, recognition dynamics.

Pairwise entanglement and local polarization of Heisenberg model

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Science China(physics,Mechanics & Astronomy) 2008年第10期51卷 1515-1522页

作者： XI XiaoQiang1,2. ZHANG Tao3. YUE RuiHong3.4 & LIU WuMing2.1 Department of Applied Mathematics and physics, Xi’an Institute of Post and Telecommunications, Xi’an 710061, China 2.beijing National Laboratory for{2. matter physics, Institute of physics, chinese academy of sciences, beijing 100080, China 3.Institute of Modern physics, Northwest University, Xi’an 710069, China 4 Department of physics, Ningbo University, Ningbo 3.52.1, China Department of Applied Mathematics and physics Xi’an Institute of Post and Telecommunications Xi’an China beijing National Laboratory for condensed{2. {3. Institute of Physics Chinese Academy of Sciences Beijing China Institute of Modern physics Northwest University Xi’an China Department of physics Ningbo University Ningbo China

The characteristics of pairwise entanglement and local polarization (LP) are dis-cussed by studying the ground state (states) of the Heisenberg XX model. The re-sults show that: the ground state (states) is (are) composed of the micro states with the minimal polarization (0 for even qubit and 1/2.for odd qubit); LP and the prob-ability of the micro state have an intimate relation, i.e. the stronger the LP, the smaller the probability, and the same LP corresponds to the same probability; the pairwise entanglement of the ground state is the biggest in all eigenvectors. It is found that the pairwise entanglement is decreased by the state degeneracy and the system size. The concurrence approaches a fixed value of about 0.3.12.(for odd-qubit chain) or 0.3.91 (for even-qubit chain) if the qubit number is large enough.

关键词： Heisenberg XX model local polarization pairwise entanglement