Acta Physica Sinica
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Acta Physica Sinica  
  Acta Physica Sinica--1987, 36 (12)   Published: 15 December 1987
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BRIEF REPORT

NEUTRON DIFFRACTION STUDY OF Mn-Zn FERRITE CONTAINING TITANIUM

YANG JI-LIAN, ZHANG BAI-SHENG, XU ZHI-JIANG, ZHOU HUI-MING, JIN LAN, YE CHUN-TANG, YU MEI, ZHOU ZENG-JUN
Acta Physica Sinica. 1987, 36 (12): 1610 doi: 10.7498/aps.36.1610
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Mn-Zn ferrite was used extensively in a variety of communications. The frequency range is from several hundreds kHz to several MHz. But in the range of -40-80℃ the temperature coefficient of the permeability of the pure Mn-Zn ferrite is rather high which makes the working frequency to drift a little. This causes some trouble in use. In order to improve μ(T) curve, a variety of elements were taken to add to the Mn-Zn ferrite. It has been found out that the μ(T) curve is improved efficiently by adding only a small amount of titanium to the Mn-Zn ferrite. In order to understand the effect of titanium in the material, the neutron diffraction structure analysis of Mn-Zn ferrite containing titanium was carried out. The experimental results show that Ti atom occupies B site, Mn and Zn occupy A site preferentially. In addition the magnetic moment per molcule was also measured. The results are discussed preliminarily.

INVESTIGATION OF DIFFUSION MARKER IN THE FORMATION OF TiSi2 THIN FILMS

HU REN-YUAN
Acta Physica Sinica. 1987, 36 (12): 1614 doi: 10.7498/aps.36.1614
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By means of Xe ion implantation as a diffusion marker, we have deterinined that Si is the dominant diffusion element in the formation of TiSi2 thin film. Applying the equation of Kioson and Tu with the result of our experiment, diffusion coefficients of Si and Ti in forming TiSi2 at 600℃ has been calculated.

A PHENOMENOLOGICAL MODEL FOR 0- MESON (Ⅱ)——THE ELECTROMAGNETIC FORM FACTOR

WU ZI-YU, WANG KE-LIN, LAN HUI-BIN, ZHANG ZHENG-GANG, XIAN DING-CHANG
Acta Physica Sinica. 1987, 36 (12): 1618 doi: 10.7498/aps.36.1618
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The physical space-like electromagnetic form factor has been calculated directly from the Euclidean 0- meson wave functions solved for the flat bottom potential in the Euclidean space. Numerical results show that the theoretical calculation may be in accordance with experiment by appropriately choosing the parameters.

INTERBAND OPTICAL PROPERTIES OF AN n-DIMENSIONAL SOLID AND HARMONIC OSCILLATOR MODEL THE N/2-FOLD INTEGRAL RELATIONS

HE XING-FEI, MO DANG
Acta Physica Sinica. 1987, 36 (12): 1624 doi: 10.7498/aps.36.1624
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We demonstrate that the interhand dielectric function and its k-th derivative spectrum near an n-dimensional critical point can be evaluated from the harmonic oscillator dielectric function and its k-th derivative spectrum, respectively, by using n/2-fold integration. The physical characteristics of harmonic oscillator in the interband spectra of an n-dimensional solid are exhibited by the action of n/2-fold integral operator. Relations between interband transitions and harmonic oscillator model, and between optical properties and dimensionality are discussed. In the fractional integral expressions for the interband optical responses, dimensionality n can be generated to an arbitrary continuous parameter.

FINITE CLUSTER STUDIES OF THE FQHE

XIONG XIAO-MING, ZHOU SHI-XUN
Acta Physica Sinica. 1987, 36 (12): 1630 doi: 10.7498/aps.36.1630
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Finite cluster system of two dimensional electron gas under a high magnetic field are investigated by numerical diagonalization of the Hamiltonian. Especially for the three Coulomb interacting electron system, the detailed study is presented. The contribution from the uniform neutralizing background is included. Method used in this paper is very simple. The numerical result of the ground state energy at 1/3 filling factor gives good approach to that of the incompressible fluid.

THE FLUX PINNING EFFECTS OF NON-IDEAL PLANE ELECTRON SCATTER CENTRE

DING SHI-YING, YU ZHENG, SHI KE-XIN
Acta Physica Sinica. 1987, 36 (12): 1635 doi: 10.7498/aps.36.1635
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A model of non-ideal plane of electron scatter flux pinning is proposed. The spread of △K/K are calculated under this model. Using GL free energy formula, The dependences of flux pinning force on thickness of the plane and impurity of matrix and electron scatter probability are obtained. The results agree well with experimental data qualitatively.

THE CRITICAL CURRENT OF MULTILAYER PbBi/SiO FILMS

DING SHI-YING, YU ZHENG, SHI KE-XIN, YAN JIA-LIE
Acta Physica Sinica. 1987, 36 (12): 1640 doi: 10.7498/aps.36.1640
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Multilayer PbBi/SiO film samples are prepared with alternative vacuum-evaporating method. Their critical currents are measured at various temperatures and in parallel and perpendicular applied magnetic fields. A variety of characteristics of critical current are found.

DETERMINATION OF SUPERCONDUCTING ENERGY GAP OF HEAVILY DOPED Re THIN FILMS BY ELECTRON TUNNELING

WANG RUI-LAN, LI HONG-CHENG, GUAN WEI-YAN
Acta Physica Sinica. 1987, 36 (12): 1643 doi: 10.7498/aps.36.1643
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The superconducting energy gap of heavily doped Re thin films has been measured by electron tunneling of Re/Al2O3/Al junctions. We get △0= (1.04±0.02) meV, 2△0/KTc = 3.31±0.04. The △0 value is determined by the maximum conductance method. It is shown that the energy gap and the Tc of Re films increases many times by impurity, but Re remains a weakly coupled superconductor.

ANTIBUNCHING OF THE STIMULATED EMISSION FROM A THREE LEVEL CASCADE ATOM

LIU ZHENG-DONG
Acta Physica Sinica. 1987, 36 (12): 1645 doi: 10.7498/aps.36.1645
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The second-order correlation functions of the stimulated emisson in the case of a three-level cascade atom interacting with radiation fields initially in coherent states or chaotic states are disccused. It is found that there exists photon antibunching.

SQUEEZING PHENOMENON IN THE CASCADE TWO-PHOTON PROCESS

LI XIAO-SHEN, LIU ZHENG-DONG, GONG CHANG-DE
Acta Physica Sinica. 1987, 36 (12): 1652 doi: 10.7498/aps.36.1652
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The Schrodinger's equation method is used to investigate the squeezing phenomenon of the electromagnetic field in the case of a three-level cascade atom interacting with single-mode cavity field. The effects of the stimulating strength and the coupling constants on the squeezing phenomenon are discussed. Furthermore, the roles played by the saturation effect and the two-photon process, and the relation between the 1st order coherence and the squeezing effects of the field are revealed.

THE THEORY OF NONLINEAR FREQUENCY MIXING EFFECT IN TRANSVERSE ZEEMAN He-Ne LASER

JIN HAO-RAN, WANG QING-JI, ZHENG LE-MIN
Acta Physica Sinica. 1987, 36 (12): 1658 doi: 10.7498/aps.36.1658
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Based on the previous paper[1], in this work we consider the Maxwell's distribution of atomic velocities, study the near degenerate four-wave mixing effect in transverse Zeeman He-Ne laser by using the vector field model and Lamb's semiclassical theory. We give out the formulas of high-order nonlinear effect, explaine theoretically the physical reason of the beat frequency distortion, and have done the numerical calculation by using computer. The results show that the predictions of theory in this paper are in keeping with experimental results.
CONTENT

STRESS STUDIES OF AMORPHOUS a-Si:H/a-SiNx:H HETEROJUNCTIONS AND a-Si:H, a-SiNx:H FILMS

WANG WAN-LU, LIAO KE-JUN
Acta Physica Sinica. 1987, 36 (12): 1529 doi: 10.7498/aps.36.1529
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We have found experimentally that the stress in a-Si:H films is Compressive, and tensile in a-SiNx:H film on the flate silicon substrate with certain content of Si-H bond. The stress in a-Si:H/a-SiNx:H/c-Si system can be made to reach a minimum by suitably chosing some conditions of depositing. The minimum stress may keep for a long time. It is shown that the stress changes with annealing temperature. Some explanation to these results are also given.

THE COMPENSATION OF DEFECTS AND DOPING IN LPCVD a-Si FILMS

ZHANG PEI-XIAN, YAO JIE, PENG SHAO-QI
Acta Physica Sinica. 1987, 36 (12): 1538 doi: 10.7498/aps.36.1538
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The studies for detects compensation and doping of LPCVD grown a-Si materials have been made by ESR, σD, σph, SIMS and Eα measurements. It is found that these materials can still be doped, although with no detectable hydrogen content. In particalar, the films can be doped effectually, and the Fermi level can be moved obviously toward the band edge in the heavily doped zone. In this paper, based on the new point of view about a-Si doping presented by Street recently, the mechanism for a-Si doping without hydrogen is explained in terms of defect compensation and chemical coordination.

A STUDY OF INTERFACES OF Co-TREATED γ-Fe2O3 THIN FILMS

DING YAO-GUO, LIN ZHANG-DA, QI SHANG-XUB, WANG YIN-JUN, QIAN JING-FANG
Acta Physica Sinica. 1987, 36 (12): 1545 doi: 10.7498/aps.36.1545
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The interfaces between CoO and Fe2O3 films have been studied, the results show that the simple CoO-γ-Fe2O3 interface has practically no effects on magnetic properties, and that the "complicated diffused interfaces" is anlikely to be the major factor in the enhancement of coercive force as previously believed. The Hc enhancement is likely to be a body effect caused by Co-doping rather than an effect of interfaces.

AN EXAFS STUDY FOR STRUCTURE RELAXATION OF Cu55Zr45 METALLIC GLASS DURING NATURAL AND ARTIFICIAL AGEING

LIU WEN, HUANG SHENG-TAO, TANG CHENG-HUANG, XU GUO-SHU
Acta Physica Sinica. 1987, 36 (12): 1551 doi: 10.7498/aps.36.1551
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The structure change of Cu55Zr45 metallic glass during natural and artificial ageing was investigated with EXAFS method. For comparison, the structure of quenched specimen was also determined. The corresponding phenomena after the specimen was aged artificially was studied with the small angle X-ray scattering and DSC, which are suitable for observing structure relaxation. Finally, according to the facts observed, a model of phase separation was suggested to explain the EXAFS of the specimens and their change during ageing.

A STUDY ON STRUCTURE AND ELECTRICAL PROPERTY OF AMORPHOUS MATERIALS IN SYSTEM AlF3-K2NbOF5

CUI HUA, YUAN QI-HUA, CUI WAN-QIU
Acta Physica Sinica. 1987, 36 (12): 1557 doi: 10.7498/aps.36.1557
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In this paper, the ionic conduction in the glass system AlF3-K2NbOF5 have been studied. The structure of glasses is also primarily established by Raman spectroscopy. The ionic conductivity of glasses is further discussed, based on the change of composition and structure. For glasses in system AlF3-K2NbOF5, when A1F3 content ranges from 21-26 mol%, A13+ and Nb5+ ions are in octahedral coordination, and the ionic conductivity increases with increasing AlF3 content. When A1F3 content reaches 29 mol%, A13+ ions are partly in tetrahedral coordination, and the ionic conductivity decreases. The effect is supposed to be caused by A1F4- ion tetrahedron. Because of the appearance of A1F4- ion tetrahedron, the mobile ion channels are possibly blocked. The ionic conductivity of glasses in this system is 1.045×10-2Ω-1·cm-1.at 194℃.

THE LIFETIME MEASUREMENT OF THE 27Al(p,a)24Mg RESONANT REACTION AT ∑p = 1565 keV BY THE PLANAR BLOCKING EFFECT

JIN WEI-GUO, ZHAO GUO-QING, SHAO QI-YUN, REN YUE-HUA, WU XIANG-JIAN, ZHOU ZHU-YING
Acta Physica Sinica. 1987, 36 (12): 1564 doi: 10.7498/aps.36.1564
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The (111) planar blocking effect is used to measure the lifetime of the 27Al(p, α)24Mg resonant reaction at Ep=1565keV and analytical methods is used to deduce the lifetime. The (111) planar blocking dip of the Ep=1183.4 keV resonance in the 27Al(p,α)24Mg reaction is also measured and compared with that calculated by theoretical calculations. The obtained lifetime τ=17.9-4.0+4.4 as is in good agreement with that obtained by the〈110〉axial blocking effect and that reported in the literature within the range of errors.

NARROW WAVE BEAM-TYPE GRAVITATIONAL RADIATION OF SPACE ARRAYS

LI FANG-YU, TANG MENG-XI
Acta Physica Sinica. 1987, 36 (12): 1570 doi: 10.7498/aps.36.1570
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This paper touches upon gravitational radiant power and radiant angle distribution of space rectangular lattice arrays of mass quadrupole oscillators, and gives analytic expression. The calculation show that these arrays can generate narrow gravitational radiation wave beam which has the best directional property. The travelling wave typegravitational radiation theory, developed by Seki and his colleagues, may be regarded as a specific case of the work in this paper and can be derived naturally. Under the codition of ideal ultrahigh frequency acoustic resonance and perfect travelling wave type synchronism intensification, an numerical example calculated with our method shows that energy flux density of gravitational radiation of optimum direction of space array which consists of 100 CaS crystals of 30×30×0.03 cm3 would amount to 2.84×10-1 erg/cm2·s. This result shows the potentiality of crystal space arrays exciting high-frequency gravitational radiation.

A PROOF ON THE EQUIVALENCE OF TOPOLOGICAL ENTROPY AT SUBREGION WINDOW OF RLm

WENG JIA-QIANG, KONG LING-JIANG, CHEN GUANG-ZHI
Acta Physica Sinica. 1987, 36 (12): 1583 doi: 10.7498/aps.36.1583
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We demonstrate that topological entropy is equivalent on the whole subregion of RLm, We also show that the high-order chaotic bands give no contribution to topological entropy in these tubregions.

THE THEORY OF SUPERCONDUCTIVITY IN CeCu2Si2 AND UBe13 (Ⅰ)——MODEL, Tc AND ORDER PARAMETERS

XU JI-HAI
Acta Physica Sinica. 1987, 36 (12): 1590 doi: 10.7498/aps.36.1590
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The phenomena of the heavy-fermion superconductivity (HFS) of CeCu2Si2 and UBe13 were theoretically inveotigated by starting from the periodic Anderson lattice model and considering the interaction between the localized electrons and the localized lattice deformation. Throngh the calculations, we obtained a reasonable superconducting transition temperature Tc and showed that the parameter which describes the isotopic effect a<1/2, even equals to zero (in BCS theory a = 1/2). We showed that the isotopic effect is smaller in our theory than that in BCS theory, even there could exist no isotopic effect in our model, the result is in agreement with the experimental facts of HFS. In addition, the curves of the order parameters varing with the temperature and the density of state are given and the conclusion of f-electrons to be responsible for HFS can be obtained naturally.

THE KINETIC DRIFT CYCLOTRON LOSS CONE INSTABILITIES IN AN INHOMOGENEOUS MEGNETIC FIELD

GUO SHI-CHONG, SHEN JIE-WU, CAI SHI-DONG
Acta Physica Sinica. 1987, 36 (12): 1598 doi: 10.7498/aps.36.1598
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The kinetic effects of magnetic drift resonance on the drift cyclotron loss cone instability (DCLC) are studied in detail both analytically and numerically. It is found that the effects of inhomogeneous magnetic field in high β plasmas are important, the kinetic resonance act as a dissipative effect, which can enhance the instability and broaden the unstable region of negative energy DCLC mode. Finite β effects do not play the stabilization role predicted by the theories under the fluid approximation.
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