Search

Article

x

Vol. 19, No. 9 (1963)

1963-05-05
Topics
CONTENT
THE QUANTUM THEORY OF FERROMAGNETISM
KUANG YU-PING, YI YU-PING
1963, 101 (9): 541-559. doi: 10.7498/aps.19.541
Abstract +
By taking account of the non-integer number of d electrons per atom and the intra- atomic interactions of electrons, a quantum theory of ferromagnetism is given. The spontaneous magnetization and the magnetic anisotropic constant K1 in the whole temperature range are calculated by using the method of double-time Green's functions in statistical mechanics. The results obtained are better than that of the simple Heisenberg's model. The properties of the temperature dependence of K1 may be explained qualitatively.
ANALYSIS OF A TWO-STROKE OSCILLATOR MODEL HAVING THE GOODWIN CHARACTERISTIC
YU CHUEI-PANG
1963, 101 (9): 567-582. doi: 10.7498/aps.19.567
Abstract +
A Le Corbeiller oscillator having the Goodwin characteristic is one of the simplest two-stroke oscillator model, its periodic process was discussed by Le Corbeiller and de Figueiredo with the help of Liénard construction-a graphical method[5] in [1] and [2]. In this paper, the above problem is approached from analytic ways. Starting from the Lord Rayleigh type equation: x+f(x)+x=0 (1) by means of the piecewise linear method, the reduced characteristic F(x) is written as f(x)={-2h1x x2x-k x>b, where h1, h2,b, k are constants. By using the point-transformation and sussesor-func-tion theory[3], the author proves that when 0 1 2 1 2, there is an unique and stable periodic solution of (1), and the oscillation has the soft-excitation character.The analytic expressions of the period and waveform for stable periodic solution are also given.
THE ELECTRON SPIN RESONANCE SPECTRA OF AROMATIC IONS
CHIU TSU-WEN, WANG WEN-YUN, CHANG SU-SHIN
1963, 101 (9): 583-598. doi: 10.7498/aps.19.583
Abstract +
In this article, about 30 aromatic ions have been studied with the элр-2 975 Kc high frequency modulation spectrometer. Most of them show well resolved hyperfine patterns. Part of them is compared with the theoretical hyperfine patterns deduced from the McConnell's σ-π configurational interaction theory and Hückel L.C.A.O.-M.O. theory. The coincidence between experimental and theoretical patterns is considered to be satisfactory.
EFFECT OF IMPERFECTIONS ON SPIN WAVES IN FERROMAGNETS
LI YIN-YUAN, FANG LI-ZHI, GU SHI-JIE
1963, 101 (9): 599-612. doi: 10.7498/aps.19.599
Abstract +
A general theoretical approach is developed to treat the effect of point imperfections on the spin waves in a ferromagnetic crystal. Special attention is paid to the formation of localized modes. As an example, the calculations have been carried out for a one-dimensional linear lattice. The main results obtained indicate the following features. A substitutional magnetic impurity atom may introduce more than one localized mode of spin waves. The conditions for the localized modes to appear and the positions of their energy levels are given in terms of J′S′/JS and J′/J. Here S′ and S are respectively the spin quantum number of the impurity and that of the normal atoms. J′ and J are respectively the exchange integral between an impurity and its neighbors and that between the normal neighboring atoms. Highly concentrated strains and interstitial atoms which cause the exchange interaction between the atoms in their neighborhood to increase lead also to the formation of localized modes. Furthermore, the dipole-dipole interaction has been taken into consideration with the conclusion reached that it should not destroy the existence of these localized modes. Discussions have been given to the discrete energy levels which appear below the continuous spectrum in case of J′<0. It is pointed out that the Holstein-Primakoff approximation adopted in the present work is not quite legitimate for certain cases in which on one or more atoms the spin deviation becomes not very much smaller than 2S or 2S′.
1963, 101 (9): 613-616. doi: 10.7498/aps.19.613
Abstract +