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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 Condensed Matter physics, {3. 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

Electronic structure and magnetism of R(Fe,si)_(12. (R=Y,Nd)

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science China(physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： sUN Guang’ai1, CHEN Bo1, DU Honglin2. FAN Zhijian1, GAO Tao3.& QI Xinhua3.. {2. of Nuclear physics and Chemistry, China {2. of Engineering physics, Mianyang 62.900, China 2. Department of physics, Peking university, beijing 100871, China 3. {2. of Atomic and Molecular physics, sichuan University, Chengdu 610065, China institute of Nuclear physics and Chemistry China Academy of Engineering Physics Mianyang China Department of physics Peking university Beijing China institute of Atomic and Molecular physics Sichuan University Chengdu China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, si)12.compounds (R = Y, Nd) are calculated using the method. The distribution of si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOs) and partial density of states (PDOs) for different crystal sites si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10si2.(R = Y, Nd) are larger than those of RFe10M2.(M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. si(8j) reduce the mag-netic moments of Fe at three sites, however, si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of si atoms according to spin fluctuation of DOs at Fermi level.

关键词： (L)APW+lo method R(Fe si)12.R = Y Nd) magnetic moment Density of state.

Global analysis theory of climate system and its applications

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chinese science Bulletin 2003年第10期48卷 1034-1039页

作者： LI Jianping1,2.& CHOU Jifan2.3.1. LAsG, institute of Atmospheric {2., {2. {3. of sciences, beijing 10002., China 2. Department of Atmospheric sciences, Lanzhou University, Lanzhou 73.000, China 3. Training Center for China Meteorological Administration, beijing 100081, China LAsG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Department of Atmospheric sciences Lanzhou University Lanzhou 730000 China Training Center for China Meteorological Administration Beijing 100081 China

The idea and main theoretical results of the global analysis theory of climate system are briefly summarized in this paper. A theorem on the global behavior of climate system is given, i.e. there exists a global attractor in the dynamical equations of climate, any state of climate system will be evolved into the global attractor as time increases, indicating the nonlinear adjustment process of climate system to external forcing. The different effects of external forcing, dissipation and nonlinearity on the long-term behavior of solutions are pointed out, and some main applications of the global analysis theory are also introduced. Especially, three applications, the adjustment and evolution processes of climate, the principle of numerical model design and the optimally numerical integration, are discussed.

关键词：整体分析理论气侯体系应用不定性计算法则气侯科学数字模型

Ashkin-Teller Formalism for Elastic Response of DNA Molecule to External Force and Torque

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Communications in Theoretical physics 2008年第2期49卷 525-528页

作者： CHANG Zhe~1 WANG Ping~(1,2. ZHENG Ying-Hong~(1,2. 1 institute of high {2. {3.,the chinese academy of sciences,P.O.Box 918(4),beijing 100049,China 2.Graduate school,the chinese academy of sciences,beijing 100049,China institute of high {2. {3. the Chinese Academy of Sciences P.O. Box 918(4) Beijing 100049 China Graduate school the Chinese Academy of Sciences Beijing 100049 China

We propose an Ashkin Teller-like model for elastic response of DNA molecule to external force and *** base-stacking interaction is described in a simple and uniform *** obtain the phase diagram of dsDNA,andin particular,the transition from B form to the s state induced by stretching and *** elastic response of thessDNA is presented also in a unified *** close relation of dsDNA molecule structure with elastic response isshown *** calculated folding angle of the dsDNA molecule is 59.2..

关键词： dsDNA elastic property

Entropy of three-dimensional BTZ black holes

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中国科学：物理学、力学、天文学英文版 2004年第3期47卷 277-283页

作者： GAO Changjun1,2.& sHEN Yougen1,2.3.4 1.shanghai Astronomical Observatory,chinese {2. of sciences,shanghai 2.003.,China(mailing address) 2.National Astronomical Observatories,chinese {2. of sciences,beijing 100012.China 3.institute of Theoretical physics,chinese {2. of sciences,beijing 100080,China 4.shanghai United Center for Astrophysics,shanghai 2.02.0},China shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China National Astronomical Observatories Chinese Academy of Sciences Beijing China institute of Theoretical physics Chinese Academy of Sciences Beijing China shanghai United Center for Astrophysics Shanghai China

The entropies of scalar field and neutrino field are calculated in the background of three-dimensional BTZ black hole. Considering statistical physics,we propose not to consider the superraradiant modes for bosons (Fermion fields do not display supperradiance).In fact,the nonsuperradiant modes do contribute exactly the area entropy for both bosons and fermions. The result shows that the neutrino field entropy is 3.2.times the scalar one.

关键词： BTZ black holes, entropy, supperradiant modes.

IMAGING IN high energy AsTRONOMY

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空间科学学报 1998年第S1期18卷 12-20页

作者： LI Ti-pei (institute of high Enerpy {2., The {3. academy of sciences, beijing 10003.)

space research is usually costly, and this restricts participation of developing countries. With traditional techniques one must construct high resolution instrument,more and more complicated and expensive, to obtain high resolution results from space observations. It is a difficult task to make observations with both high sensitivity and high resolution. Applying advanced inversion technique, one can subtract more information from old data in public domain,and, furthermore, conduct high sensitive and high-resolution experiments with low-cost low-resolution instruments. so developing and applying data analysis technique is of great importance for developing countries to do basic space *** this paper we summarize efforts of chinese scientists in recent years along this direction on imaging in space high energy astronomy.

关键词： space astronomy Astronomical satellite Imaging

Polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

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chinese Chemical Letters 1997年第8期8卷 725-728页

作者： Zhen Zhong YANG De Lu ZHAo Mao XU(Polymer physics Laboratory, institute of Chemistry, The {2. {3. of sciences, beijing 100080) Polymer physics Laboratory Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG), and the effect of the concentration of the catalyst on the reaction is studied. It is shown that there exist two competitive reactions : I, self polymerization of epoxy resin via chain growth and II, copolymerization of epoxy resin with PEG via step growth. At high concentration of the catalyst reaction I dominates and reaction II is negligible. On the contrary, at low concentration of the catalyst, reaction II dominates and block copolymers are formed In the intermediate case, the two reactions are comparable with the result that a gel structure is obtained.

关键词： PEG Polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

Properties of the 3.2.-[52.] band in the odd-N rare-earth nuclei

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science China(physics,Mechanics & Astronomy) 2011年第S1期54卷 37-43页

作者： CHEN Liang1,2. ZHOU XiaoHong1,2. ZHANG YuHu1, ZHANG shuangQuan3.& ZHU LiHua4 1institute of Modern {2., {2. {3. of sciences, Lanzhou 73.000, China 2.raduate University of {2. {3. of sciences, beijing 100049, China 3.tate Key Laboratory of Nuclear {2. and Technology, school of {2., Peking University, beijing 100871, China 4China institute of Atomic energy, beijing 102.13. China institute of Modern physics Chinese Academy of Sciences Lanzhou China Graduate University of chinese academy of sciences Beijing China state Key Laboratory of Nuclear physics and Technology School of Physics Peking University Beijing China China institute of Atomic energy Beijing China

high-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2.[642., {2.2.[52.], and 11/2.[505] configurations have been extended up to high-spin states, and particularly, the α = -1/2.branch of the ground state {2.2.[52.] band has been revised significantly. It is found that signature inversion occurs in the {2.2.[52.] band after the band crossing in 161Er. The systematics of the signature inversion associated with the {2.2.[52.] configuration in the rare-earth region is discussed. The band properties are analyzed within the framework of a triaxial particle-rotor model, and a triaxial deformation is proposed to the {2.2.[52.] band.

关键词： high-spin states signature inversion triaxial particle-rotor model

On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

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chinese physics C 2018年第7期42卷 113-122页

作者： Yi-Qing Guo1 2.Qiang Yuan1 3.1. Key Laboratory of Dark Matter and space Astronomy Purple Mountain Observatory chinese {2. of sciences Nanjing 2.0008 China 2. Key Laboratory of Particle Astro{2. {3. of high energy {2. Key Laboratory of Dark Matter and space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Sciences school of Astronomy and space science University of Science and Technology of China

More than fifty years after the discovery of the knee in the cosmic ray （CR） spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectra of individual components. Recently, direct measurements from several space experiments found significant spectral hardenings of CR nuclei at ~2.0 GV. A joint modeling of the direct and indirect measurements may help to understand the experimental systematics and the physics of the knee. In this work, we update the phenomenological ＂poly-gonato＂ model to include the spectral hardenings, with a changing spectral index of γ ＋ β·logE. This modification gives a reasonable description of the CR spectra in a wide energy range. However, the fits to different data sets give different results. We find that the fit to the AMs-02.and CREAM data slightly favors a relatively low energy knee of the light components. In such a case, the expected all-particle spectra under-shoot the data, which may require an extra component of CRs. The fits to AMs-02.data and the light component （H＋He） data from the Tibet Asγ/ARGO-YBJ/WFCTA and KAsCADE experiments give consistent results with the all-particle spectra. We further propose a possible physical realization of such a ＂modified poly-gonato＂ model of spectral hardenings by means of spatially-dependent diffusion of CRs. We find reasonably good agreement between the model predictions and the data for CR spectra, the secondary-to-primary ratios, and the amplitude of anisotropies.

关键词： cosmic ray knee spectrum propagation