Vol. 38, No. 10 (1989)
MAGNETIC PROPERTIES AND VARIABLE VALENCE OF Pr ATOM FOR THE AMORPHOUS RE-TM THIN FILMS (RE=Nd, Pr, TM=Fe, Co, Ni)
1989, 38 (10): 1551-1558. doi: 10.7498/aps.38.1551
Through the investigation of the low temperature magnetic properties for the amorphous light rare-earth (Pr, Nd) and transition metal (Fe, Co, Ni) alloy thin films, the composition dependence of the magnetic moment for each of Pr, Nd, Fe, Co and Ni atoms in these alloys can be determined. We found that the delocalization of 4f electron of Pr atom may be studied by analyzing the variation of the magnetic moments of the Fe, Ni and Pr atoms with presence of the Pr component.
ORBITAL SPIN-SPLITTING FACTORS FOR CONDUCTION ELECTRONS IN LEAD: DE HAAS-VAN ALPHEN STUDIES WITH MAGNETIC FEEDBACK
1989, 38 (10): 1559-1568. doi: 10.7498/aps.38.1559
Using the magnetic feedback technique, a detailed experimental study has been made on the spin-splitting factors gc associated with the conduction electrons in extremal orbits on the Fermi surface of lead, by measuring the relative strengths of the harmonic amplitudes of the de Haas-van Alphen waveform. Particular attention has been paid to the influence of sample inhomogeneity. Experimental gc values are given for most of the extremal orbits on the lead Fermi surface for high-symmetry directions of  ,  , and  of the magnetic field. These gc values are found to span the range from 0.71 to 1.147. The large deviation from the free-electron value are consequences of strong spin-orbit and electron-phonon interactions.
1989, 38 (10): 1569-1577. doi: 10.7498/aps.38.1569
In this paper, based on the concept of building blocks with interactions, we study the stability of models of Si(lll) 7×7 reconstructed surface. With use of tight-binding method, we calculated formation energies of various building blocks and their interactions. With these building blocks, various large unit surfaces can be constructed and their total energies can be easy estimated, without heavy calculations. We evaluate the surface energies of Si(lll) 5×5 and 7×7 DAS models, and get the results of -0.467 eV and -0.477 eV, respectively, close to the results of Qian and Chadi. Moreover, we point out that neither the 7×7 adatom model nor the 7×7 adatom-vacancy model are stable.
1989, 38 (10): 1578-1584. doi: 10.7498/aps.38.1578
The electronic structures of Si (111) surface have been studied by means of molecular orbital theory of SCF-CNDO with the cluster model treatment. The calculated results show that: (1) The distribution and transfer of net charges in thesurface have localized characters at the atomic orbitals. Also, the T30, T3+ and T3-defect forms do not exist easily in practical system. (2) The electronic structures can be discribed with the stoohastic potential, from which one can find out the adsorption site and learn the adsorption dynamic process of ion and ionic molecules adsorbed on the Si (111) surface. (3) The surface states mainly appear in the region from the top of valence band to the centre of gap, and is strongly localized at the atomic orbitals. The above-mentioned results are consistent with some experimental discoveries.
1989, 38 (10): 1585-1592. doi: 10.7498/aps.38.1585
The small spherical α-Fe2O3 particles with uniform size and regular shape were prepared by improved hydrolysis method. The infrared transmisson spectra of this two kinds of particles different in dimension were measured, and all surface modes of small spherical α-Fe2O3 particles were obtained. The effect of aggregation on absorption were discussed, and the two absorption bands in spectra were explained with the approximation of chain aggregation by cylindrical microcrystals. Surface mode theory of multi-atomic cubic particles was generalized and applied to α-Fe2O3 particles in monoaxial crystal structure. The theoretical results of surface mode frequency of α-Fe2O3 particles were presented, which agreed well with those of experiments. The existence of generalized modified LST relation was verified.
1989, 38 (10): 1593-1600. doi: 10.7498/aps.38.1593
The reflection behavious of nonlinear optical interface between glass and liquid crystal were studied systematically. The reflection behaviours of such interface with isotropic liquid phase was studied by using a Q-switched ruby laser. The threshold intensity of transition from TIR (tolal internal reflection) to partial transmission for different incident angle were measured at T-Tc = 2.5℃. It agrees with the plane wave theory of Kaplan. The time resolved reflection of nonlinear interface was also measured and hysteresis loop of reflectivity was observed. The hysteresis loop of reflectivity can be attributed to the deorientation relaxation processes of liquid crystal molecules. The nonlinear optical interface between glass and ne-matic liquid crystal was also studied using an Ar+ laser. The transition from TIR to partial transmission was observed at the intensity 700 W/cm2. This transition can be attributed to thermal induced phase transition from nematic mesophase to isotropic liquid phase.
1989, 38 (10): 1601-1610. doi: 10.7498/aps.38.1601
In this paper, the optical Bloch equations of a two-level atom ensemble driven by squeezed light field are derived. Based on these equations, we calculate the atomic absorption and dispersion. The results show that for different squeezing conditions of the field fluctuations, atomic absorption-lineshape exhibits sub-or super-natural linewidth phenomenon. Atomic dispersion depends on the squeezing direction and coherent excitation direction of the driving field. When these two directions are not parallel or perpendicular to each other, the dispersion zero-point shows a shift to the transition frequency of the atom.
1989, 38 (10): 1611-1620. doi: 10.7498/aps.38.1611
Theoretical evaluation of the angular scattering enhancement around the back-scattering direction from a randomly rough surface is studied by employing the Kirchhoff approach. An analytic expression of polarized double-scatterered intensity that takes into account the coherence of multiple scattering from the rough surface is used to quantitatively evaluate the scattering enhancement around the back-scattering direction from such a surface.
1989, 38 (10): 1621-1627. doi: 10.7498/aps.38.1621
A fractal model of the interface between electrolyte and electrode has been proposed. The ac frequency response of the interface is discussed. The phenomenon of the constant phase angle (CPA) impedance expressed by Zp= A(iω)-p discovered in the measurements is explained. A relation between the exponent p and the dimension D of the fractal interface p=(4-D)/2 is obtained and compared with those suggested by others previously.
1989, 38 (10): 1628-1633. doi: 10.7498/aps.38.1628
The total conductivity and the electronic conductivity of 45Li2O·50B2O3·5MmOn (M= Al, Ti, Zr, P, V, Nb, Ta, Cr, Mo, W) glasses are measured. The Raman spectra of the glasses are studied. The influence of MO2, M2O3 and MO3 oxides is discussed based on the pro-perties of the negatively charged groups acting as the localization sites for Li+ ions.
THE PRESSURE DEPENDENCE OF THE EXPANSIVITY AND OF THE ANDERSON-GRüNEISEN PARAMETER IN THE GENERAL CONDITION
1989, 38 (10): 1634-1641. doi: 10.7498/aps.38.1634
In this paper, the general relations between the Anderson-Grüneisen parameter and the first derivative of the bulk modulus with respect to pressure and between the bulk modulus and pressure are derived theoretically. And from these relations, we further obtain the pressure dependence of the Anderson-Grüneisen parameter and of the coefficient of thermal expansion under general conditions.
THE MICROSCOPIC PHENOMENOLOGICAL THEORY OF ANALYSIS FOR THE PROBLEM OF NONE-QUILIBRIUM FLUCTUATIONS (Ⅱ)——NONEQUILIBRIUM FLUCTUATIONS OF SOME PHYSICAL SYSTEMS AND COMPAR-ISON WITH EXACT RESULTS FOR HEAT CONDUCTIONS OBTAINED FROM AN INFORMATION-THEO
1989, 38 (10): 1642-1647. doi: 10.7498/aps.38.1642
We apply the theory established in ref.  and the general results to treat heat fluctuations in dielectric materials, by considering the phonon heat conduction in one, two and three dimensions, as well as in metals, where we deal with electronic heat conduction. We compare our results with an exact solutions from an exact model for the nonequibrium fluctuations in a linear harmonic chain based on an information-theoretical approach. These solutions coincide reasonably. And so prove the theory presented in  is correct.
1989, 38 (10): 1648-1657. doi: 10.7498/aps.38.1648
We developed a many-body method to calculate the electron correlated basis function of excited state. Based on the Chakravarty-Woo equation and functional expansion and convolution approximation, we got the linear integral iteration equation for the variation of density and correlation function, so the wave function, due to electron excitation. A general formula for excitation energy in many-body problem is obtained From this and the known experimental data, we found the energy gap and electron correlation in 1-d conducting polymer. The result is in good accordance with the experiment.
1989, 38 (10): 1658-1664. doi: 10.7498/aps.38.1658
Using two-step laser excitation, we obtained the spectrum of highly excited nf series of Al. Stark effect induced forbidden transition lines, line shifts and line broadening are also observed. The theoretical analysis is presented.
This paper discribes the measurements of Rydberg energy levels of Ru in 4d7(4F) ns (n=28-45) and 4d7(4F) nd (n=26-48) series by means of laser resonance excitation-electric field ionization method. The first ionization potential of Ru has been determined by nonlinear fitting program. These energy levels and relevant quantum defects have been calculated by using relativistic self-consistent field method The theoretical results are coincident with the experiments very well. Besides, the first ionization potential drawn from this papes has been compared with the existing data.
1989, 38 (10): 1673-1678. doi: 10.7498/aps.38.1673
The solutions in Dyson boson representation are discussed in this paper. We point out that the physical essence of the solutions, including dydamical symmetry, is independent of the concrete representation. The solutions can be obtained by transforming the matrix of HD into triangular matrix. In some situations, this method is very simple.
1989, 38 (10): 1679-1686. doi: 10.7498/aps.38.1679
A simplified model of one dimensional elastic dipole discrete lattice containing oscillating dislocations is proposed to study the nonlinear stress-induced diffusion of interstitials in the inhomogeneous stress field of dislocation and to set up a foundation for further numerical calculation in real crystals, consequently, to clarify the interaction of the external stress, the dislocations and the octahedral interstitials in bcc crystals and to explain S-K relaxation and the effect of dislocation on Snoek relaxation theoretically. The simulation computation shows that the nonlinear diffusion of interstitials induced by the dislocation stress field makes the interstitials form a Fermi-Dirac distrubution of defects and enhances Snoek effect, hence, a peak of Snoek effect of nonlinear diffusion appears at higher temperature than that of Snoek peak.
1989, 38 (10): 1687-1697. doi: 10.7498/aps.38.1687
The crystal structures of all R1+εFe4B4 compounds are composed of two intepe-netrating tetragonal substructures. and form the Vernier structures. The symmetries of R1+εFe4B4 are characterized by two approaches, those of the space group under the commensurate model Rp(Fe4B4)q and the superspace group. The results indicate that the space gtoup symmetry can be applied to R1+εFe4B4 by constructing a long period superstructure Rp(Fe4B4)q, whose symmetries have been shown to be dependent on the parity of p and q. Space groups P42/n, Pccn, and Ccca(in a revised supercell) can cover the symmetry of Rp(Fe4B4)q for the different parity combinations of p and q, which is in agreement with the experimental results. The supersymmetry of all these compounds can be represented by an orthogonal superspace group PssiCmma. The related systematic extinctions are discussed, and the selection rules of Vernier structures, those can not be explained by three-dimensional space group, are obtained.
1989, 38 (10): 1698-1703. doi: 10.7498/aps.38.1698
In this paper, the M?ssbauer spectra of amorphous Fe90-xCoxZr10 (x=4, 10, 20,…70) and Fe90-yCryZr10 (y = 0, 4, 7, 16, 20) series of alloys were studied. The experimental results indicated that, a-Fe90-yCryZr10 and a-Fe90-xCoxZr10 in Fe-rich regions contain two different local coordination structure, which produce both ferromagnetic and antiferromagnetic states below Tc and different paramagnetic states above Tc. When x is above 30, in a-Fe90-xCoxZr10 alloys exists only one ferromagnetic state, which implies magnetic "homogeneity". The micro-structures of amorphous transition metal (TM)-TM alloys were discussed in some detail.
X RAY DOUBLE CRYSTAL DIFFRACTION STUDY OF (BiTm)3(FeGa)5O12 MAGNETIC GARNET FILMS GROWN BY LIQUID PHASE EPITAXY
1989, 38 (10): 1704-1709. doi: 10.7498/aps.38.1704
The investigation of (BiTm)3(FeGa)5O12 single crystal films grown by liquid phase epitaxy (LPE) at different temperatures is made by means of X-rays double crystal diffractometry and polarized optical microscopy. The study indicates that the temperature of LPE is very important. With the decrease of temperature, the crystal lattice parameter increases. The crystal film includes two layers of different crystal latticeparameter or orientation. When the crystal lattice misfit ((as-af)/(as)) between the subst-rate and the film is greater than 10-3, the film will crack.
1989, 38 (10): 1710-1716. doi: 10.7498/aps.38.1710
The MBE GaAs1-xSbx/GaAs strained layer quantum well has been investigated by means of photoreflectance measurement. The energy band structure has been estimated by theoretical fitting with the experimental results. We confirmed that the variations of band structure caused by hydrostatic component of the strain mainly exist in conduction band, and that MBE GaAs1-xSbx/GaAs strained layer quantum well is a typical one of type Ⅱ. The theoretical estimation coincide well with our experimental results.
A potential model for atoms is employed to calculate the scalar and tensor polarizabilities of Rydberg states (15≤n≤55) of Na, K, Rb and Cs. The results are very close to the experimental values. The scaling relations of the polarizabilities a = An*7 + Bn*6 are also established, and the results obtained from them also agree with experimental data satisfatorily.
1989, 38 (10): 1723-1726. doi: 10.7498/aps.38.1723
In this paper, the approximation of optical Fourier transform in the cases of defocus is studied, and the relation of condition required for the defocus approximation of Fourier transform is derived. From this principle a method of using the defocus approximation is described for deblurring an electronic micrographic image, which makes the optical deconvolution process significantly simplified. The experimental results show that the quality of the image of an amorphous carbonic film is notably improved.