Table of Content

20 August 1996, Volume 5 Issue 8 Previous Issue    Next Issue

GENERAL

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TOPOLOGICAL CLASSIFICATION OF 3D AND 2D SPIN STATES IN THE FERROMAGNETS CONTAINING ANNULUS- AND CYLINDER-TYPE CAVITIES GAO TING, YAN FENG-LI, LI BO-ZANG 1996, 5 (8):  561-567.  doi: 10.1088/1004-423X/5/8/001 Abstract ( 0 )   PDF (198KB) ([an error occurred while processing this directive])   Methods of algebraic topology have been employed to classify ordinary (3D) and planar (2D) spin states in the ferromagnets containing annulus- and cylinder-type cavities. The main result of this paper is that the sets of homotopy classes of 3D and 2D spin states in a ferromagnet containing m non-winding up annulus-type cavities threaded by k cylinder-type cavities can be constructed into groups isomorphic to Zm and Zm+k, respectively. Here m,k = 0, 1, 2,…,Zl denotes the l-dimensional discrete vector group.

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EXPERIMENTAL STUDIES ON INTERMITTENT PHENOMENA IN A PLASMA MA LIAN-XI, SUN HONG-YAN, WANG LONG 1996, 5 (8):  568-578.  doi: 10.1088/1004-423X/5/8/002 Abstract ( 0 )   PDF (250KB) ([an error occurred while processing this directive])   An intermittent process occurring in a low-temperature plasma discharge has been investigated. During a continuous scan of the discharge voltage, one kind of intermittency evolves from random upward bursts to a periodic oscillation, while the other evolves to chaos from random downward bursts. A critical exponent concerning the onset of the latter intermittency is quantitatively determined to be γ= 0.912.

ATOMIC AND MOLECULAR PHYSICS

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STUDY OF Mg 3sns AND Sr 5sns RYDBERG STATES DAI CHANG-JIAN 1996, 5 (8):  579-589.  doi: 10.1088/1004-423X/5/8/003 Abstract ( 0 )   PDF (271KB) ([an error occurred while processing this directive])   Energy levels of the Mg 3sns and Sr 5sns Rydberg states have been studied using multichannel quantum defect theory. The wavefunctions derived from the energy levels are utilized to calculate natural radiative lifetimes of the Rydberg states with n≤15. The present work is compared with the previous experiments and theoretical results, the agreement is satisfactory.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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INTERFACE FORMATION OF Ge/ZnSe(100) AND Ge/ZnS(111) HETEROJUNCTIONS STUDIED BY SYNCHROTRON RADIATION PHOTOEMISSION BAN DA-YAN, YANG FENG-YUAN, FANG RONG-CHUAN, XU SHI-HONG, XU PENG-SHOU 1996, 5 (8):  590-600.  doi: 10.1088/1004-423X/5/8/004 Abstract ( 0 )   PDF (321KB) ([an error occurred while processing this directive])   The microscopic evolution of interface formation between Ge and Ⅱ-Ⅵ compounds such as ZnSe and ZnS single crystals has been studied by synchrotron radiation photoemission spectroscopy and low energy electron diffraction. Core level intensity measurements from the substrate as well as from the overlayer show a nearly ideal two-dimensional growth mode for the deposition of Ge on ZnSe(100) surface. How-ever, there is a certain deviation from the ideal two-dimensional mode in the case of Ge/ZnS(111) due to the diffusion of substrate atoms into Ge overlayer. Surface semi-tire core level spectra indicate that the reaction of Ge with S atoms at Ge/ZnS(111) interfaces is much stronger than that of Ge with Se atoms at Ge/ZnSe(100) interfaces.

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COHERENT OPTICAL PHONON EXCITATION BY FEMTOSECOND LASER PULSE IN YBa2Cu3O7-δ THIN FILMS PI FEI-PENG, LIN WEI-ZHU, MO DANG 1996, 5 (8):  601-608.  doi: 10.1088/1004-423X/5/8/005 Abstract ( 0 )   PDF (256KB) ([an error occurred while processing this directive])   With a correlation of nonequilibrium carriers relaxation and coherent phonons displacive excitation, the coherent optical phonon oscillations in YBa2Cu3O7-δ thin films excited by femtosecond laser pulse are simulated theoretically. It is revealed that as the oxygen concentration decreases, the coherent phonon oscillations become easier to be observed due to the decrease of the local coupling between the carriers and the lattice vibrations in the CuO2 plane.

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FORMATION AND MAGNETIC PROPERTIES OF Dy2Fe17-xMnxC(x = 0-17) PREPARED BY ARC-MELTING WANG FANG-WEI, ZHANG PAN-LIN, SHEN BAO-GEN, YAN QI-WEI 1996, 5 (8):  609-613.  doi: 10.1088/1004-423X/5/8/006 Abstract ( 0 )   PDF (164KB) ([an error occurred while processing this directive])   We report on alloys formed by replacing iron with manganese in the compound Dy2Fe17C1.0 Samples were characterized by X-ray diffraction and magnetic measure-ments, The 2:17-type structure can be crystallized in the whole range of manganese substitution. The Curie temperature of the series of Dy2Fe17-xMnxC1.0(x= 0-17) drops down considerably from 515K for x = 0 to about 20K for compounds with high manganese concentration, and the compensation point was observed in a narrow range of x≈4-6. The rapid decrease of the magnetization shows that the manganese substitution is not a simple magnetic dilution to the transition-metal sublattice mo-ment, it indicates that the moment of Mn may be antiparallel to that of Fe. The field dependence of the magnetization of Dy2Fe17-xMnxC1.0 may indicate the existence of the nonlinear magnetic structure for the samples with high Mn conoentrations.

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INFLUENCE OF IN-PLANE FIELD ON THE STABILITY OF VERTICAL BLOCH LINE CHAINS IN HARD DOMAINS OF GARNET BUBBLE FILMS HAN BAO-SHAN, MENG GUANG-QING, NIE XIANG-FU, TANG GUI-DE, SUN HUI-YUAN, GUO GE-XIN 1996, 5 (8):  614-619.  doi: 10.1088/1004-423X/5/8/007 Abstract ( 0 )   PDF (181KB) ([an error occurred while processing this directive])   The stability of vertical Bloch line (VBL) chains was statistically studied for all three types of bard domains in garnet bubble films subjected to an in-plane field Hip. With a set of integrate data taken from seven bubble samples and with two typical figures of a sample, four main features of the behavior of VBL chains subjected to Hip were summarized.

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A NON-ADIABATIC MODEL OF SINGLE BUBBLE SONOLUMINESCENCE CHEN WEI-ZHONG, WEI RONG-JUE, WANG BEN-REN 1996, 5 (8):  620-629.  doi: 10.1088/1004-423X/5/8/008 Abstract ( 0 )   PDF (276KB) ([an error occurred while processing this directive])   A non-adiabatic model of single bubble sonoluminescence has been advanced through considering the energy dissipation caused by light emission. The bubble dynamical equations with a black-body radiation have been solved numerically. The results show that without introduciag any model parameter, this model not only can well reproduce the experimental phenomena in the time scale of microsecond of the adiabatic model can do, but also can obtain a 40-100 ps of flash duration and a 104 K effective temperature of the black-body radiation. These agree with the experiment quite well.