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 Z^{m} and Z^{m+k}, respectively. Here m,k = 0, 1, 2,…,Z^{l} denotes the l-dimensional discrete vector group.

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.

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

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.

With a correlation of nonequilibrium carriers relaxation and coherent phonons displacive excitation, the coherent optical phonon oscillations in YBa_{2}Cu_{3}O_{7-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 CuO_{2} plane.

We report on alloys formed by replacing iron with manganese in the compound Dy_{2}Fe_{17}C_{1.0} 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 Dy_{2}Fe_{17-x}Mn_{x}C_{1.0}(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 Dy_{2}Fe_{17-x}Mn_{x}C_{1.0} may indicate the existence of the nonlinear magnetic structure for the samples with high Mn conoentrations.

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 H_{ip}. 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 H_{ip} were summarized.

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 10^{4} K effective temperature of the black-body radiation. These agree with the experiment quite well.

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