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Vol. 34, No. 11 (1985)

1985-06-05
CONTENT
MAGNETIC PERMEABILITY RELAXATION IN AMORPHOUS Fe82Si5B13 ALLOY
ZHANG YAN-ZHONG
1985, 34 (11): 1377-1384. doi: 10.7498/aps.34.1377
Abstract +
The kinetic behavior of the isothermal relaxation of the magnetic permeability has been investigated for the amorphous Fe82Si5B13 alloy in the range 0-300℃. Four relaxation peaks are observed on the isochronal relaxation spectrum for as-quenched alloy. The overale relaxation usally consists of both the ordinary disaccommodation and the continuous permeability decay, they are reversible and irreversible with respect to demagnetization, respectively. The calculations or the distributions of the relaxation time and the activation energy show that they have a broad distribution. The most probable activation energies for disaccommodation and decay are about 1.0 eV and 1.4 eV, respectively. A cross-over effect in the decay is observed for annealed sample.
STUDY OF MAGNETIC PROPERTIES (SPIN REORIENTATION PHASE TRANSITIONS) IN Sm2(TM)17 ALLOYS
LIN HONG, ZHONG WEN-DING
1985, 34 (11): 1385-1395. doi: 10.7498/aps.34.1385
Abstract +
The magnetic properties of pseudobinary Sm2(FeNiCoM)17 alloys in which M are nonmagnetic elements have been studied. The sample consists of disordered hexagonal 2:17 phase (TbCu7-structure) coexisting with FeNi. Anomalous magnetic properties along the c-axis (easy magnetization direction) have been observed. Below the room temperature, the magnetization and reverse magnetization curves exhibit obvious jumps. The magnetic fields corresponding to the jumps Hr increase with the temperature decreasing. The hysteresis loops show wasp-waisted character. The curve of magnetization vs. temperature has a maximum, the corresponding transition temperature Tt decreases with the magnetic field increasing. During cooling, the thermal magnetic hysteresis phenomena have been found at some values of magnetic field. On the basal plane (hard magnetization direction) and at higher Co concentrations (>18at%), the alloys show normal ferromagnetic behaviors. Most of the phenomena observed can be explained in terms of spin reorientation phase transition leading to non-collinear spin arrangements. The reversal of spin direction must cross over an evergy barrier, the height of which is U = 9.2×10-15 erg. The calculated values of magnetization are in good agreement with the observed ones.
FORMATION OF HARD BUBBLES BY SINGLE-PULSE BIAS FIELD
NIE XIANG-FU, TANG GUI-DE, HAN BAO-SHAN, XI WEI
1985, 34 (11): 1396-1406. doi: 10.7498/aps.34.1396
Abstract +
The formation of hard bubbles by single-pulse bias field in epitaxial garnet films was investigated in some detail. It was verified by experiments and calculations that, in general, VBL in hard bubble walls are not generated by the way that one Bloch line pair is produced per pulse. The dependence of the hardening of soft domain segments on their movements was revealed by means of the method of double exposure photography. Two kinds of favorite movements for hard bubble formation were discovered and the physical meaning of the" demarcation field for soft and hard bubble formation" H[b] was elucidated.
STUDY MAGNETISM BY MAGNETOSTATIC WAVES
ZHANG PENG-XIANG, CAO KE-DING
1985, 34 (11): 1407-1412. doi: 10.7498/aps.34.1407
Abstract +
We constructed a device to excite and detect magnetostatic modes in. slab ferrite samples for frequency range of 2-8GHz. Using this device, we set up a system to measure relation between frequency and applied magnetic field for magnetostatic waves. This system can be used to study not only the magnetostatic waves, but also the basic properties of ferrites. It is similar to FMR. However, the samples need not to be put into a microwave cavity, thus the system allows one to make measurements during some sample treatment.
THE TOTAL VOLUME FRACTION OF VOIDS OF RF SPUTTERED AMORPHOUS SILICON
FEI QING-YU, HUANG BING-ZHONG
1985, 34 (11): 1413-1421. doi: 10.7498/aps.34.1413
Abstract +
The principle and method of measurement and calculation of the total volume fraction of voids of RF sputtered amorphous silicon by speetroscopic ellipsometry and effective medium theory is described. It is found that the changes in the electrical and optical properties among amorphous silicon films deposited in different argon pressure may be satisfactorily explained in terms of changes in the total volume fraction of voids. This suggests that it is significant to measure and calculate the total volume fraction of voids of a-Si. The good agreement between the result of total volume fraction of voids and the measured result of total volume fraction occupied by Ar atoms shows the validity of the method.
THERMODYNAMIC PROPERTIES OF THE ONE-DIMENSIONAL EXTENDED HUBBARD MODEL(Ⅰ)——U>0
ZHANG KAI-YI, XU HUI
1985, 34 (11): 1422-1432. doi: 10.7498/aps.34.1422
Abstract +
A perturbation expansion for the thermodynamic potential is performed to the third order by HTSE method. Entropy, internal energy, specific heat, and magnetic susceptibility of the one-dimensional extended Hubbard model are computed as functions of temperature, electron density, and t, U, W. Thermodynamics can be discussed in two temperature regions. The high T-region corresponds to increase in number of double occupied states. The low T-region corresponds to the distribution of electron spin. The effect of t on thermodynamic properties is obvious.
THERMODYNAMIC PROPERTIES OF THE ONE-DIMENSIONAL EXTENDED HUBBARD MODEL (Ⅱ)——U<0
ZHANG KAI-YI, XU HUI
1985, 34 (11): 1433-1441. doi: 10.7498/aps.34.1433
Abstract +
Entropy, internal energy, specific heat, and magnetic susceptibility of the one-dimensional negative-U extended Hubbard model are computed. An analytical solution of magnetic susceptibility in the strong-coupling (|U|→∞) limit is obtained. Therma-dynamic properties of the system can be discussed in two temperature regions. The high T-region corresponds to decrease in number of double occupied states. The low T-region corresponds to the distribution of electron charge. The effect of W on the-rmodynamic properties is obvious.
A MODEL FOR LOCAL MAGNETIC MOMENT AND ITS DELOCALIZATION OF f ELECTRONS IN METALS (Ⅰ)
CHEN CHANG-FENG, ZHANG LI-YUAN
1985, 34 (11): 1442-1450. doi: 10.7498/aps.34.1442
Abstract +
In this paper we suggest a model in which f electrons are bound in a narrow band near Fermi level, s-p-d electrons are regarded as free, and hybridization between them is considered. Numerical results show that certain stability of f electrons exists under delocalization and is dramatically influenced by temperature and hybridization. Phase diagrams in different parameter spaces are plotted. Finally the case of intermediate valence in RE is discussed qualitatively.
NEW GENERAL METHOD OF X-RAY DIFFRACTION QUANTITATIVE PHASE ANALYSIS WITHOUT STANDARDS
GUO CHANG-LIN, YAO GONG-DA
1985, 34 (11): 1451-1460. doi: 10.7498/aps.34.1451
Abstract +
In this paper, a new general method of X-ray quantitative phase analysis without standards is presented. The limit conditions that the phase composition of each of the reference samples and the analysis sample must be equal in Zevin's method are no more to be required. When the analysis sample contains n0 phases, each of the reference samples could contain less or more phases than n0. Hence, our new method is more general. The quantitative methods in both cases of known and unknown mass absorption coefficients are discussed. Practical quantitative analysis have proved that, the new method is quite explicit and applicable as well as gives quite precise and satisfactory quantitative analysis results.
MULTIPHASE DOPING METHOD IN QUANTITATIVE X-RAY DIFFRACTION PHASE ANALYSIS
YAO GONG-DA, GUO CHANG-LIN
1985, 34 (11): 1461-1468. doi: 10.7498/aps.34.1461
Abstract +
The pure doping samples of single phase are necessary to the common doping me-thods in quantitative X-ray diffraction phase analysis. In this paper, the new multiphase doping method in X-ray quantitative analysis is presented. If the analysis sample contains n phases, (n-1) suitable multiphase reference doping samples are required to determine the amounts of each phase in the analysis sample, but each doping sample would not contain more than (n-1) phases. This method can also be applied to determine only the amounts of several of the phases in the analysis sample. Practical quan-titative analysis have proved that, the new method is quite applicable and gives quite precise and satisfactory quantitative analysis results.
NON- RELATIVISTIC AND RELATIVISTIC ATOMIC CONFIGURATION INTERACTION THEORY EXCITATION ENERGY AND RADIATIVE TRANSITION PROBABILITY
ZHAO ZHONG-XIN, LI JIA-MING
1985, 34 (11): 1469-1478. doi: 10.7498/aps.34.1469
Abstract +
We have established the non-relativistic and relativistic atomic configuration interaction methods to calculate excitation energies of low excited states as well as radiative transition probabilities for allowed and forbidden transitions. In order to check our computer codes, we have calculated the excitation energies for N=2 states and the corresponding radiative transition rates for the atomic helium. The results of our non-relativistic and relativistic calculations agree with each other. The excitation energies are accurate within a few thousandths, the corresponding radiative transition probabilities within a few percents. Our methods can be readily applied to other atoms as well as ionized atoms.
MINIMA OF OSCILLATOR STRENGTH DENSITIES FOR EXCITED ATOMS
LIANG XIAO-LING, LI JIA-MING
1985, 34 (11): 1479-1487. doi: 10.7498/aps.34.1479
Abstract +
Based on Hartree-Slater self-consistent potentials, we have studied minima of oscillator strength densities, namely, zeroes of electric dipole matrix elements for excited alkli atoms (here oscillator strength densities proportional to photoabsorption cross sections). Thus we have induced further the systematics about the zeroes of dipole matrix elements between eigenchannels for other excited atoms, namely, the relation between the zeroes and the quantum defect differences for corresponding initial and final channels. Based on such a relation, we predict the photoabsorption windows for excited Ne(3s) and excited Ar(4s), which have been confirmed by a recent experiment.
BRIEF REPORT
THE FERMION'S MASS TERMS IN AN SU(2) MODEL AND THE RUBAKOV EFFECT
LI XlN-ZHOU, ZHANG JIAN-ZU, WANG KE-LIN
1985, 34 (11): 1488-1493. doi: 10.7498/aps.34.1488
Abstract +
In an SU(2) spontaneously broken gauge theory with a Higgs triplet, the mass effect of an isospin-1/2 fermion on the fermion-monopole bound states is discussed. It is shown that when the direct coupling between fermion and Higgs field approaches zero, but the Dirac mass is kept finite, then the necessary condition of the fermion-monopole bound state is not satisfied. This result means that the Rubakov effect is absent for SU(2) monopole because of the Dirac mass.
THE MODIFIED EXCITED-STATE POLARIZATION MODEL
XIAO DING-QUAN
1985, 34 (11): 1494-1499. doi: 10.7498/aps.34.1494
Abstract +
The excited-state polarization model is modified by taking into account the different pyroelectric processes in polar crystals and the difference between the mean emission frequency ν2 and the electronic transition frequency ν3 which results from the stokes shift in the radiative trasition. According to this model, the results for the dipole moment charge △μfrom different specimens of crystal LiNbO3 :Cr3+ used by different authors are identical within experimental errors: △μis about 3 Debye, and almost indepeudent of temperature in the whole experimental temperature region 50—300 K.
SCALING RELATION OF GENERALIZED OSCILLATOR STRENGTH DENSITY ALONG ISOELECTRONIC SEQUENCE
PAN XIAO-CHUAN, LI JIA-MING
1985, 34 (11): 1500-1508. doi: 10.7498/aps.34.1500
Abstract +
The differential cross section and total cross section of high-energy electron impact excitation can be calculated by Born approximation. The differential cross section is propotional to the so called generalized oscillator strength. The target atom or ion may be excited to infinite number of bound states and adjoint continuum states which can be treated in an unified manner by Quantum Defect Theory. Thus, we define generalized oscillator strength density (GOSD) as the generalized oscillator strength per unit of excitation energy. We have calculated the GOSD's of the lithium-like isoelectronic se-quence(Li, Be+, B++, C3+, Ne7+, Na8+, K16+) for excitation from the ground state to S, P, D and F channels. The scaling relation along isoelectronic sequence is discussed.
GENERAL EQUATION OF FOUR PROBES METHOD FOR RESISTIVITY MEASUREMENT OF SEMICONDUCTOR MATERIALS
CHEN CUN-LI
1985, 34 (11): 1509-1515. doi: 10.7498/aps.34.1509
Abstract +
The equation of four probes method for resistivity measurement requires point contacts and a definite configuration of probes array. In fact, the contacts are always with definite dimension. In this article, we drive the equations of measuring resistivity and surface sheet resistance, taking into account the contact dimension and putting the location of the four probes arbitrary. The in-line four probes and the square array four probes are two specific examples for the equations.
STRUCTURAL RELAXATION OF AMORPHOUS ALLOYS Fe13.3Ni69.6B16.2Si0.9
CHEN JIN-CHANG, SI HUNG, ZHAN WEN-SHAN, SHEN BAO-GEN, ZHAO JIAN-GAO
1985, 34 (11): 1516-1520. doi: 10.7498/aps.34.1516
Abstract +
Structural relaxation kinetics and reversible relaxation processes of amorphous alloys Fe13.3 Ni69.6 B16.2 Si0.9 are discussed in this paper. Changes in the Curie temperature, Tc, due to various heat treatments are studied. It is found that Tc approaches equilibrium values after prolonged annealing, and the relaxation kinetics can be described by the relaxation time spectrum. Relaxation relaxation process can be explained by CSRO, and we note that the reversible change in one property does not imply that the change of entire structure is reversible.