Table of contents

20 April 1996, Volume 5 Issue 4 Previous issue    Next issue

GENERAL

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AN ALTERNATIVE ONE-PARTICLE QUANTUM THEORY WITH A NEW EXPECTATION VALUE POSTULATE LIU QUAN-HUI (刘全慧) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  241-249.  DOI: 10.1088/1004-423X/5/4/001 Abstract ( 1087 )   PDF (217KB) ( 348 )   Our recent treatment of some single-particle systems implies that if the expectation value postulate in usual quantum theory is changed in some proposed way, we can also have a self-consistent and reasonable one-particle quantum theory. In this paper, the framework of the theory barmonized with a newly proposed self-energy quantum electrodynamics is given. Our theory is compatible with Einstein's completeness. It in statistical ensemble reproduces the results given by the usual theory and in classical limit reduces to the classical mechanics for the single-particle systems.

ATOMIC AND MOLECULAR PHYSICS

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DISTORTED WAVE-WAVE PACKET APPROACH TO VIBRATIONAL DEACTIVATION OF DIATOMIC MOLECULE BY COLLISIONS WITH SOLID SURFACE REN TING-QI (任廷琦), LIU SHENG-DIAN (柳盛典), HE JING-LIANG (何经良), ZHANG QING-GANG (张庆刚) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  250-254.  DOI: 10.1088/1004-423X/5/4/002 Abstract ( 1071 )   PDF (134KB) ( 334 )   A model is proposed for vibrational dexcitation of diatomic molecule by collisions with a solid surface, and used to predict the rotational and translational energy distributions and other properties of interest. It is found that molecular rotation dominates over translation in receiving the vibrational energy released, even for the heavier diatomic molecules.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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MOLECULAR ORIENTATION AND COLOR ALTERNATION OF SURFACE STABILIZED FERROELECTRIC LIQUID CRYSTAL CELL XIAO SHENG-AN (肖胜安), CHEN TIE-QI (陈铁岐), XU KE-SHU (徐克(王寿)) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  255-263.  DOI: 10.1088/1004-423X/5/4/003 Abstract ( 1012 )   PDF (255KB) ( 334 )   Molecular orientation configurations across zig-zag defects and thin-line defects of the surface stabilized ferroelectric liquid crystal (SSFLC) cell are presented. The transmission spectra of the SSFLC cell of non-uniform states are numerically calculated using the asym-metric chcvron structure model. The calculations agree well with experimental results, which confirms the continuity of the N-director across the chevron interface. The color alternation of the SSFLC cell between crossed polarizers is well explained.

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

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ANALYTICAL AND ITERATIVE SEMICLASSICAL SOLUTIONS FOR THE GIANT MAGNETORE-SISTANCE IN MAGNETIC MULTILAYERS LI BO-ZANG (李伯臧), WU JIAN-HUA (吴建华), PU FU-CHO (蒲富恪) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  264-280.  DOI: 10.1088/1004-423X/5/4/004 Abstract ( 1012 )   PDF (412KB) ( 337 )   Based on the semiclassical theory of Camley and Barnas(C-B), the problem of solving the giant magnetoresistance in magnetic multilayets (Fi/Ni)n/Fn+1 is comprehensively discussed with both the bulk and interface spin-dependent scatterings being involved. The solution of this problem is attributed to the solution of G-coefficients (G's). First, we point out that for large n the analytical solution in close form ia hard to obtain and a recent attempt made in the literature failed in general. Second, a new choice of local spin quantization-axes is adopted for reducing (in comparison with C-B) the number of G's and several exact infer-ences are drawn in order to further simplify the solution of G's. Finally, an iteration method for solving G's is developed, which, we believe, is the simplest one among the numerical methods in this area and leads naturally to the analytical solutions with close expression in the case of small n. Such solutions are given for symmetric sandwich as well as superlattice.

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ITERATIVE SEMICLASSICAL SOLUTIONS OF CIP GIANT MAGNETORESISTANCE IN MAGNETIC MULTILAYERS WITH MIXED LAYERS TAKEN INTO ACCOUNT LI BO-ZANG (李伯臧), WU JIAN-HUA (吴建华), PU FU-CHO (蒲富恪) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  281-294.  DOI: 10.1088/1004-423X/5/4/005 Abstract ( 1079 )   PDF (347KB) ( 358 )   The problem of solving semiclassically the current in-plane (CIP) giant magnetoresistance in magnetic multilayers with mixed layers taken into account is comprehensively studied. The solution of this problem is attributed to the solution of G-coefficients. A new choice of local spin quantization-axes is adopted so that the number of G-coefficients is reduced from Johnson-Camley's 4(5n+1) to our 4(4n+1). Furthermore, we show that actually only a half number of G-coefficients need be sloved for the symmetric structure and a superlattice can be simplified to a symmetric penta-layered structure. The main result of this paper is the establishment of the iteration method for solving the G-coefficients. Associating this method with that of numerical integration, for which a formulism is developed, the GMR. can be conveniently calculated.

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BROADENING OF RESISTIVE TRANSITION AND IRREVERSIBILITY LINE FOR EPITAXIAL YBa2Cu3O7-$\delta$ THIN FILM XU XIAO-JUN (许小军), LI KE-BIN (李可斌), FANG JUN (方军), WANG ZHI-HE (王智河), CAO XIAO-WEN (曹效文) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  295-299.  DOI: 10.1088/1004-423X/5/4/006 Abstract ( 1267 )   PDF (143KB) ( 333 )   The broadening of resistive transition of c axis oriented epitaxial YBCO thin film has been measured for three configurations: (1) H∥c and H⊥I; (2) H∥ab plane and H⊥I; (3) H∥ab plane and H∥I in magnetic field up to 8 Teala(T), and for different angle $\theta$ of magnetic field relative to the ab plane with H = 4T. The results obtained indicate that the broadening of resistive transition is mainly determined by the angle $\theta$, but is hardly related to the angle $\alpha$ made between magnetic field and tran sport current in ab plane. This means that the broadening of resistive transition is not determined by flux motion drived by apparent Lorentz force. Au expression of angular dependence of irreveraibility line has been given.

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INFLUENCE OF THE SUBSTRATE ON THE MAGNETOSTATIC MODES OF A FINITE SUPERLATTICE LI BIAO (李飚), YANG JIE (杨杰), SHEN JUE-LIAN (沈觉涟) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  300-305.  DOI: 10.1088/1004-423X/5/4/007 Abstract ( 1099 )   PDF (136KB) ( 366 )   In a finite layered system, the substrate influences the spectra of the collective excitations. We solve the dispersion relations for magnetostatic modes in a finite Cd0.30Mn0.70Te-Cd0.89Mn0.11Te multilayer structure as a prototype antiferromagnetic and paramagnetic su-perlattice grown on the top of a nonmagnetic or a paramagnetic substrate. In perpendicular magnetization geometry where the saturation magnetization lies along the growth axis of the layered structure, surface modes appear in the spectra when the substrate is paramagnetic but disappear when the substrate is nonmagnetic. At the same time, the bands of bulk modes in the spectra are independent of change of substrates.

CROSS DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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SOLUTE REDISTRIBUTION IN THE INITIAL TRANSIENT REGION OF DIRECTIONAL SOLIDIFICATION SPECIMEN MA DONG (马东), JIE WAN-QI (介万奇) Acta Physica Sinica (Overseas Edition), 1996, 5 (4):  306-311.  DOI: 10.1088/1004-423X/5/4/008 Abstract ( 949 )   PDF (144KB) ( 351 )   The solute redistribution during initial transient process of directional solidification of a binary alloy is associated with the solid-liquid interface advancing velocity which will pass a hysteretic process approaching to the externally imposed velocity. In the present paper, a new accelerated growth equation, dV/dt = μG[$\frac{m}{G}$·$\frac{{\rm d}G^*_{\rm L}}{{\rm d}t}$+Ve-V] is deduced, based on which a new formula for the initial transient solute redistribution is obtained with the reasonable assumption that the solid-liquid interface advancing velocity changes exponentially during solidification. It shows that the kinematic effect dominates solidification at high velocity while the coupling effect of thermal and mass transportation controls that at lower velocity.In addition, another new equation to calculate the time required for a planar interface to lose stability is also found. Since the effects of the imposed thermal gradient are taken into account in the new equations, they are more reasonable and satisfactory than those given by Tiller et al.[1] and by Smith et al.[2]