Vol. 42, No. 10 (1993)
1993-05-20
GENERAL
1993, 42 (10): 1543-1549.
doi: 10.7498/aps.42.1543
Abstract +
The calculated formula for partition function of one-Dimensional Fibonacci quasiperiodic frustrated Ising system with free and periodic boundary conditions are given in this paper. Its thermodynamical properties at low temperatures are studied. It is found that when the temperature tends to zero , the thermodynamical quantities as the functions of B/J show discontinuities at B/J=2/(2m+l) (m interger). The ground state configuration of system in various parameter regions are described and the results of calculation are discussed.
1993, 42 (10): 1550-1555.
doi: 10.7498/aps.42.1550
Abstract +
The dynamical properties of Dirac spinor particles in a non-static Rindler space-time is studied. The explicit representative of the four-component wave function of Dirac particles is obtained. A non-uniformly rectilinearly accelerating Rindler observer is accompanied by an event horizon depending on time. He explores some thermal radiation varying with time, whose temperature is proportional to the simultaneous acceleration. The existence of the non-static Rindler effect is confirmed.
1993, 42 (10): 1556-1566.
doi: 10.7498/aps.42.1556
Abstract +
The behavior of Fokker-Planck Equation for a stochastic resonance problem is studied by using finite difference schemes. The numerical results coincide with the analytical approximate theory under the conditions of adiabatic approximation ω?D?△V and small signal approximation A?1. Although the system rexhibits evidently deterministic non-linear vibration properties when the amplitude of periodic driving force is large, the adiabatic approximate analytical theory can cover the principal properties of stochastic resonance which occurs in the bistable system.
1993, 42 (10): 1567-1572.
doi: 10.7498/aps.42.1567
Abstract +
We report here the experimental observations for non-propagational solitons in the one-dimensional nonlinear lattice that are damped and parametrically driven. Theoretrically, Using the method of multiple-scaling expansion. We have well brought the experimental results of both soliton and kink in both models in match and mismatch into the frame of the cubic nonlinear Schr?dinger (NLS) equation. According to NLS, we predict that the form of the self-localized structure is only determineted by the intrinsic parameters of the lattice, rather than the exciting ones.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
1993, 42 (10): 1573-1579.
doi: 10.7498/aps.42.1573
Abstract +
With a general Gaussian wave functional, we study the ground states, one particle states, and two particle states of the sine-Gordon model. At the Coleman's critical point, the sine-Gordon system tends to a system of massless free bosons which possesses conformal symmetry. We also show that there exist bound states in two particle states as long as the renormalized mass remains finite.
ATOMIC AND MOLECULAR PHYSICS
1993, 42 (10): 1580-1586.
doi: 10.7498/aps.42.1580
Abstract +
In the interaction representation, the time-dependent quantum calculation formulas for the atom-oscillator scattering are derived by using angular momentum coupling theory, and the vibrational and rotational transition probabilities and the partial cross sections for the He-H2 system are calculated. The results show that: (1) the interaction picture wave function is highly localized in coordinate space and varies slowly in time, therefore, we are able to obtain higher accuracy in calculating scattering quantities, and the calculated results are in excellent agreement with that of CC method; (2) the effect of the vibration term on the calculating time is dependent upon the integration of the potential matrix, in which a calculation including only the ground state gives remarkably good results.
1993, 42 (10): 1587-1594.
doi: 10.7498/aps.42.1587
Abstract +
Based on equation of motion of the two-level atomic density matrix, we have studied theoretically the relation between the radiation force on an atom in the standing wave field and the atomic induced absorption rate and induced radiation rate. We find that the radiation force on an atom in the standing wave field consists of induced absorption force and induced radiation force. This piont of view is also valid in the circumstance of interaction between an atom and N plane waves.
CLASSICAL AREA OF PHENOMENOLOGY
1993, 42 (10): 1595-1599.
doi: 10.7498/aps.42.1595
Abstract +
The free electorn laser with cylindrical waveguide loaded with dielectric is studied by us-ing theory of fluids. It is shown that the main mode of super-radiation in this system is TE mode. It has all the characters of slow-wave free electron laser.
1993, 42 (10): 1600-1607.
doi: 10.7498/aps.42.1600
Abstract +
The dynamic behaviour of interactions between three-level atoms system driven by a co-herence microware field and optical pulse is discussel. The optical area theorem has been de-rived and the self-induced transparency has been studied. It is found that some properties of this system is the same as two-level system under some special conditions.
1993, 42 (10): 1608-1611.
doi: 10.7498/aps.42.1608
Abstract +
Two-wave mixing is realized in Ce doped KNSBN crystal by using ps light pulses with a repetition rate of 82 MHz. The experimental results recorded directly by using a streak camera and an explanation are presented.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1993, 42 (10): 1612-1616.
doi: 10.7498/aps.42.1612
Abstract +
The specific heat of polybutadien was measured and it was found that at temperature Tg = 178K there is a glass transition and the specific heat near the transition temperature depends strongly on the cooling process of the sample. After waiting at temperature Tw for a time tw during the cooling process, we found that there are waiting time effects on the specific heat of a heating process: the anomalous Δcp at Tp increases with the waiting time tw. In thecase of Tw=169K, Δcp(tw) can be described by Kohlrausch law Δcp(tw)～{l-exp[-(tw/τ)β]} with β =0.47±0.03.
1993, 42 (10): 1617-1626.
doi: 10.7498/aps.42.1617
Abstract +
Light rare earth metal (LREM,La,Ce)films of 1500? thick were deposited on Si(lOO) substrate at room temperature under UHV condition. And a variety of techniques including AES,XRD and SIMS were used to study the thin film contact reaction between LREM and Si after isothermal annealing in the range of 200-400℃ for different durations. A new thin film contact reaction mechanism was observed. Taking into account the microscopic interfacial reaction, a model was suggested to elucidate this new reaction mechanism.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1993, 42 (10): 1627-1634.
doi: 10.7498/aps.42.1627
Abstract +
Some simple solvable models, which are in connection with the molecular structure of gene code carrier deoxyribonucleic acid (DNA),are constructed. Their electronic structures are investigated and their physical properties are discussed.
1993, 42 (10): 1635-1641.
doi: 10.7498/aps.42.1635
Abstract +
The electronic structure of strained superlattices (SLS) (InAs)n(InP)n(001) are calculated with the Linearized-Muffin-Tin Orbitals (LMTO) band structure method in which the higher energy unoccupied d orbitals are treated by internal summation approach. The effects of In 4d orbitals on band structures are investigated. The valence band offsets (ΔEv) at SLS's are determined by a frozen-potential approach. The results show the bulk-like property is almost recovered in the molecular layers next to the interfaces. The band structure of (InAs)1(InP)1(001) given by the present work is well consistent with those given by more elaborate FLAPW calculation. The ΔEv values determined by the present calculation are in good agreement with those from XPS measurement and FLAPW method in which the core level or the macroscopic average potentials is used as a reference level. The small calculation effort and the satisfactory precision justify the present method as a very effective means for studying the electronic structures of multi-layers SLS.
1993, 42 (10): 1642-1647.
doi: 10.7498/aps.42.1642
Abstract +
A method for studying grain growth kinetics of thin films by means of quasi-state measurement of films resistivity is proposed. Pd films is prepared by d c sputtering in ultra-high vacuum, and relationship between resistivity of Pd films and annealling time is measured at different tempertures The change of grain size of Pd films can be calculated by using the two-fluid model and can be compared with results of TEM. It is found that annealling temperature plays an important role in grain growth process and grain growing curve is imitated. The experiment results indicate that grain growth process is thermal activated and the activation energy is about 0. 53eV.
1993, 42 (10): 1648-1653.
doi: 10.7498/aps.42.1648
Abstract +
The deformative effect of phonon states of the bath in a dissipative quantum tunneling system is studied by perturbation and a variational approach. We find that the deformative effect depends on the dimension of the bath. It increases as the dimension is reduced on one hand. On the other hand,it gives more stronger influence on the quantum tunneling system for a lower-dimensional bath.
1993, 42 (10): 1654-1660.
doi: 10.7498/aps.42.1654
Abstract +
The growth procedure of the Si/GaP( Ⅲ )heterointerface with Si electron beam evaporation in an improved ADES-400 photo-electron spectrometer is introduced in this paper. Then the status of formation and valence band discontinuities of Si/GaP(Ⅲ ) heterointerfaces that grown under different conditions are analysed or measured in situ by photoemission. The relation of the ΔEv values with the status of the interface and the shift of atomic core levels is discussed. The growth condition of the abrupt and ordered Si/GaP(Ⅲ)heterointerfaces is determined. The value of valence band discontinuity in this case is 0.80eV. It agrees with theoretical results.
1993, 42 (10): 1661-1668.
doi: 10.7498/aps.42.1661
Abstract +
Thermal fluctuations in a Josephson-fluxon oscillator are considered with emphasises on the stochastic dynamics of fluxon and the non-trivial continuum-mode excitations. Analytical expressions for the radiation line-width of the oscillator are derived from perturbation theory and standard stochastic process theory. The averaged kinetic energy of a low-velocity fluxon is shown to be kBT/2. The continuum excitations are explored in the framework of the inverse scattering transform approach. The averaged energy per wave mode turns out to be kBT,and this justifies the adiabatic approximation applied in the fluxon stochastic dynamics.
1993, 42 (10): 1669-1673.
doi: 10.7498/aps.42.1669
Abstract +
A series of single phase YBa2Cu3Oy samples with various oxygen contents and Tcmid's> 90K were prepared, and their structures, superconductivities, flux pinning behaviors have been determined and investigated. The experimental results show that the oxygen deficiencies result in enhancements of critical current density Jc and flux pinning force density Fp, moreover, there exists an optimal concentration of okygen deficiencies, corresponding to the maximal enhancemenes of Jc and Fp. Different from the cases of y= 6. 96,6. 83,Jc of y= 6.94,6.86 samples vary unmonotonicly with magnetic field H, correpondingly, the magnetization curves exhibit an abnormal peak known as "fishtail" effect. Fitted with the scaling law, it is found that when 6.83≤y≤6.94, the peak in fp(h) curves appears at the same reduced magnetic field h(≈0. 6). It indicates that the existence of oxygen deficiencies introduces new flux pinning centres in YBa2Cu3Oy.
1993, 42 (10): 1674-1679.
doi: 10.7498/aps.42.1674
Abstract +
Using a special optical transmission system, excimer laser beam can scan on the superconducting target, scanning laser beam ablates the target resulting in deposition of superconducting films. The thickness uniformity of large area superconducting films can be improved by this method. The superconducting films on 12mm×33mm Y-ZrO2 substrates show good thickness uniformity, zero resistance temperature Tc≥90K, critical current density at 77K and zero field Jc≥l×106A/cm2.
1993, 42 (10): 1680-1683.
doi: 10.7498/aps.42.1680
Abstract +
The order of phase transition of a two-dimensional Ising model with m-body interactions in the horizontal direction and n-body interactions in the vertical direction in the m = 3, n = 3 case is of the first-order which is determined by our Monte Carlo algorithm, while in the m= 3,n=2 case the transition is of the second order.
1993, 42 (10): 1684-1690.
doi: 10.7498/aps.42.1684
Abstract +
A Monte Carlo simulation study for the two-dimensional antiferromagnetic s=1/2 quantum Heisenberg model is performed using an efficient cluster algorithm developed by present authors. Comparing the finite temperature and finite size effects of various quantities with recent results from the chiral perturbation theory we determine the low energy parameters of the system very precisely. We find that e0= -0. 6693(1)J/a2 for the ground state energy density, Ms= 0.3076(4)/a2 for the staggered magnetization, ?c = 1.68(l)Ja for the spin-wave velocity and ρs= 0.185(5)J for the spin stiffness. Our results agree with the experimental data for the undoped precursor insulators of La2CuO4.
1993, 42 (10): 1691-1695.
doi: 10.7498/aps.42.1691
Abstract +
M agnetic anisotropy of a nanocrystalline Fe73.5Cu1Nb3Si13.5B9 soft magnetic alloy was investigated. Theoretical analysis and measurement results show that the effective magnetic anisotropy constant in the nanocrystalline alloys can be measured by means of the process of approaching saturation and the measured value is about one orders of magnitude smaller than the magnetocrystalline anisotropy constant K1 of the α-Fe(Si) grains.
1993, 42 (10): 1696-1702.
doi: 10.7498/aps.42.1696
Abstract +
The Er2Fe17Cx compounds with high carbon contents have been prepared by melt-spinning. The structures, phase stability and intrinsic magnetic properties of Er2Fe17Cx(x=0. 0, 0. 5,1. 0,1. 5,2. 0,2. 5,2. 8 and 3.0 ) have been investigated in detail. The influence of interstitial carbon atoms on atomic moments, exchange interaction and anisotropy has been discussed. At the same time, the hyperfine fields on various Fe sites have also been analyzed by 57Fe M?ssbauer effect.
1993, 42 (10): 1703-1706.
doi: 10.7498/aps.42.1703
Abstract +
The phase transition characteristics of ferroelectric films with domain structure were studied using Landau free energy expansion. The existence of domain walls reduces both the spontaneous polarization and the Curie temperature, and increases the critical size. The reversal length moves away from the surfaces as temperature increases. As the film becomes thinner, the film will turn into single domain.
1993, 42 (10): 1707-1711.
doi: 10.7498/aps.42.1707
Abstract +
In (CdSe)1(ZnSe)3/ZnSe short-period superlattice multiple quantum wells, we observed the Raman scattering from ZnSe confined longitudinal optical phonon modes in both the barriers and wells of quantum wells under different resonant conditions. From comparison between theoretical analysis with linear chain model and experimental results, the observed ZnSe confined longitudinal optical phonon mode in the both configuration are shown to be LO1 This differs from the observations in GaAs/AlAs quantum wells and we tentatively attribute the disagreement to the different subband structures in our sample.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1993, 42 (10): 1712-1718.
doi: 10.7498/aps.42.1712
Abstract +
The far-infrared reflectance and transmittance spectra of natural FeS2(Pyrite) at room and low temperatures are reported in this artical. The spectral structure and the physical origin are discussed in detail. Through our research we found that the plasmon reflectance edge at low frequency of room temperature reflectance spectra of FeS2(Pyrite) samples have a close relation with the natural impurity: PbS(Galena) in samples. We use the reflectance spectra at room temperature of FeS2(Pyrite) and PbS (Galena) mineral single crystals as basic spectra to reproduce the experimental spectra of different samples in various proportions. the x values we obstained form it not only reflect the relative quantities of PbS (Galena) impurity, but also have positive correlation with the noble metal: Au(Gold) indirectly. This may have some applications in mineral formation research.
