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A. Roy Chowdhury, A. Ghose Chowdhury
Subject area: Mathematical methods in physics.
1994 Volume 63 Issue 1 Pages
1-4
Published: January 01, 1994
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We have analysed an affine Gaudin Model with the help of a L-operator with entries belonging to affine Gaudin algebra. It is observed that the usual classical r-matrix does not exist, but an extended version due to Maillet and Vega (called the (r-s) algebra) can be defined. The subsequent quadratic algebra of the monodromy matrices are then used to set up the Algebraic Bethe Ansatz for the model. Relation to other similar model are discussed.
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Yutaka Shimomura
Subject area: Fluid dynamics.
1994 Volume 63 Issue 1 Pages
5-9
Published: January 01, 1994
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A new subgrid-scale (SGS) model in the large-eddy simulation of turbulence is proposed on the analogy of a reduced version of the algebraic stress model. It yields the SGS stresses by solving a system of coupled linear equations. As a result, it may overcome the deficiency of the Smagorinsky model [J. Smagorinsky: Mon. Weather Rev. 91 (1963) 99.] that the Smagorinsky constant is not universal.
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Masatoshi Yagi, Kimitaka Itoh, Sanae–I. Itoh, Atsushi Fukuyama, ...
Subject area: The physics of plasmas and electric discharges.
1994 Volume 63 Issue 1 Pages
10-13
Published: January 01, 1994
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The stability of the current-diffusive ballooning mode in tokamaks with high toroidal mode number is analyzed in the region of second stability against the ideal magnetohydrodynamic mode. It is found that the growth rate of the current-diffusive ballooning mode is decreased upon the reduction of the geodesic curvature driving force. The reduction of thermal conductivity in the limit of very weak shear or negative shear in comparision with standard shear is also shown.
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Naoya Takeda, Katsunori Tanaka, Xiao–lei Wang, Mikihiko Ikezawa, ...
Subject area: Electron states in condensed matter.
1994 Volume 63 Issue 1 Pages
14-17
Published: January 01, 1994
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We have studied the Fermi surface of the quasi-two-dimensional metal Ag
2F by use of the transverse magnetoresistance and the de Haas-van Alphen effect. The cylindrical Fermi surface perpendicular to the conductive plane was established. This Fermi surface is originally spherical but both upper and lower parts are truncated by the Brillouin zone boundary planes, and contains one electron per formula.
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Hidenobu Hori, Masahiro Furusawa, Tetsuya Takeuchi, Shunji Sugai, Koic ...
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
18-21
Published: January 01, 1994
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Magnetic properties of CuGeO
3 single crystal which shows the spin-Peierls transition below T
sp=14, K were investigated by means of high field magnetization and susceptibility measurements. The stepwise magnetization was observed in the magnetic fields along the a-, b-, and c-axes up to about 35, T. The magnetization process is different from the case of conventional uniaxially anisotropic antiferromagnets. Such a magnetization process is explained by the crossover model between the ground singlet and the excited magnetic discomensulate state. The main exchange parameter is antiferromagnetic and the estimated value from the high-field magnetization curves is 140, K (97, cm
-1). A decrease of the critical fields with increasing temperature was observed up to 14, K, the origin of which is considered to be the effect of soft phonons in the spin-Peierls transition.
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Yutaka Itoh, Hiroshi Yasuoka, Akihiko Hayashi, Yutaka Ueda
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1994 Volume 63 Issue 1 Pages
22-25
Published: January 01, 1994
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We have measured the temperature (T) dependence of the Gaussian decay rate 1/T
G associated with the
63Cu nuclear spin-spin relaxation of Tl
2Ba
2CuO
6+δ (T
c-- 85, K) by the NMR spin-echo technique. 1/T
G increases from T
c up to T
sp-- 120, K and decreases monotonically in a Curie-Weiss-like law above T
sp. In spite of the nonmonotonic T-dependence of (1/T
G)
2 [-- χ (Q)], we have found that (1/T
G)
2 scales to 1/T
1T and hence 1/T
1∝ Tχ (Q) is valid above T
c. This result indicates that the antiferromagnetic spin-fluctuation theory for the two-dimensional itinerant electron system holds for the present overdoped monolayered Cu oxide without a dynamical gap.
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Hiroshi Hayashi, Kazuhiro Nozaki
Subject area: Mathematical methods in physics.
1994 Volume 63 Issue 1 Pages
27-34
Published: January 01, 1994
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The su(2) linear system, which depends on powers of spectral parameter, is shown to be Darboux covariant. By setting Darboux invariants to be constant, we derive Darboux covariant soliton equations associated with the su(2) linear system, such as families of the cubic nonlinear Schrödinger equation, the isotropic Heisenberg equation and new coupled nonlinear equations.
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Kwok W. Chow
Subject area: Mathematical methods in physics.
1994 Volume 63 Issue 1 Pages
35-39
Published: January 01, 1994
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Recently it has been shown that the superposition of solitons constitutes an exact periodic solution of many well known nonlinear evolution equations, including, for example, the Korteweg-de Vries (KdV) and the modified KdV equations. The same phenomenon is investigated for the second modified KdV equation.
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Hiroaki Ono, Isamu Nakata
Subject area: Mathematical methods in physics.
1994 Volume 63 Issue 1 Pages
40-46
Published: January 01, 1994
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The propgation of an ion-acoustic soliton through a mass interface of cold ions in a plasma is investigated both for a discontinuous change and for a gradual change. It is shown that the behaviors of transmitted waves are similar for both cases and an incident soliton may fission when it passes through the mass interface from the region of heavy ions to that of lighter ones. It is also found that the plane of density discontinuity moves towards the propagation direction of the incident soliton after its passing.
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Il–Tong Cheon
Subject area: Classical and quantum physics: mechanics and fields.
1994 Volume 63 Issue 1 Pages
47-51
Published: January 01, 1994
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Variation of vacuum fluctuation in a finite space is discussed on analysis of the energy level shifts for
193Ir and it is shown that the energy level shifts can be drastically reduced by the effect of opaqueness of the material used to restrict the space. The theoretical values of the shifts are compared with the recent results of Mössbauer experiment.
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Takashi Nagatani
Subject area: Statistical physics and thermodynamics.
1994 Volume 63 Issue 1 Pages
52-58
Published: January 01, 1994
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We present a stochastic cellular automaton (CA) model to simulate the traffic jam induced by a car accident in the traffic flow of a two-lane roadway. The CA model is an extended version of the one-dimensional asymmetric exclusion model to take into account the stochastic exchange of cars between the first and second lanes. We study the traffic flow of the system when the translation invariance is broken by the insertion of a blockage which is induced by a car accident on the first lane. Using the computer simulation, it is found that the dynamical jamming transions occur successively from the phase 1, through the phase 2, to the phase 3 with increasing the density of cars. The phase 1 is characterized by the property such that no cars exist in the first lane and the cars on the second lane move with the maximal velocity. The phase 2 is characterized by the shock formation (a discontinuity of density) and the maximal current. In the phase 3, the discontinuity disappears and the traffic flow is not affected by the car accident.
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Katsuhiko Fujii, Shinichi Tokuzawa
Subject area: Statistical physics and thermodynamics.
1994 Volume 63 Issue 1 Pages
59-65
Published: January 01, 1994
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We studied a statistical theory of phase transition in a system consisting of orientational rotators with multiple directions, in terms of the mean field approximation, and derived the intensity formula of X-ray diffuse scattering. This theory is an extension of the Naya's approach limited in the disordered phase, so as to be able to include the ordered phase. An idea of order parameter was newly introduced, which was characterized by the eigenstates of interaction matrix between molecules and the like with multiple directions. As the result, we could find the definite direction for the critical scattering to appear.
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Yoshitaka Tanimura, Shaul Mukamel
Subject area: Statistical physics and thermodynamics.
1994 Volume 63 Issue 1 Pages
66-77
Published: January 01, 1994
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The optical Stark effect of a two-level system coupled to a Brownian oscillator (i.e. a harmonic mode which in turn is coupled to a heat bath) is studied using equations of motion for a reduced density matrix. These equations, derived using path integral techniques, can be used to study the combined effects of strong fields and dephasing processes at finite temperature, and interpolate continuously from the coherent to the overdamped limits where they reduce to the stochastic Gaussian-Markovian equation. Numerical calculations of probe absorption spectra for various pump intensities are presented, and show dynamical Stark splitting. In contrast to the Bloch equations which contain an infinite-temperature dephasing, we find that at finite temperature, the Stark peaks may have different heights even when the pump pulse is on resonance.
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Byung Geel Yu, Il–Tong Cheon, Moon Taeg Jeong
Subject area: Specific reactions and phenomenology.
1994 Volume 63 Issue 1 Pages
78-83
Published: January 01, 1994
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The electric dipole amplitude E
0+ for p(γ, , π
0)p near threshold has been extracted from the experimental data by fitting the total cross section in high energy region, E
γ >160, MeV. The result is (-1.56± 0.10)× 10
-3, m
π +-1. This amplitude is calculated by taking the vector mesons into account in the pole model of t-channel. Our analysis manifests a favor of negative sign for the ρ π γ coupling constant.
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A. V. Mohan Rao, S. N. Chintalapudi
Subject area: Nuclear reactions and scattering: specific reactions.
1994 Volume 63 Issue 1 Pages
84-91
Published: January 01, 1994
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Alpha particle induced reactions on the target elements Thulium and Tantalum were investigated upto 60, MeV using stacked foil activation technique and Ge (Li) gamma ray spectroscopy method. Excitation functions for six reactions of
169Tm(α, , xn); x=1-4 and
181Ta(α, , xn); x=2, 4 were studied. The experimental results were compared with the updated version of Hybrid model (ALICE/90) using initial exciton configuration n
0=4 (4p0h). A general agreement was found for all the reactions with this option.
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Nobuyuki Hasebe, Tadayoshi Doke, Masayuki Fujii, Ken"ichi Fujiki, ...
Subject area: Experimental methods and instrumentation for elementary-particle and nuclear physics.
1994 Volume 63 Issue 1 Pages
92-100
Published: January 01, 1994
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The energy loss straggling of heavy charged particles with relatively high energies passing through thick uniform Si detectors (1.0, mm--9.2, mm) has been studied in a wide range of the ratio ΔE/E
0 where ΔE is the energy loss and E
0 is the initial energy of the incident particles. The experimental results are compared with those predicted by straggling theories. It suggests that the measured distributions are in good agreement with those predicted from the Bohr's or Livingston-Bethe's theories when ΔE/E
0<0.3 where the distributions are to be Gaussian-symmetric. However, the distributions for larger energy losses deviate from those expected from the theories. It is found that the experimental data are approximately expressed by the modified Stoquert's theory when the ratio ΔE/E
0>0.3.
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Jiro Mizushima
Subject area: Fluid dynamics.
1994 Volume 63 Issue 1 Pages
101-110
Published: January 01, 1994
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A set of model equations, which describe the time development of the amplitudes of Fourier modes, are proposed to clarify the mechanism of the pattern formation in Rayleigh-Bénard convection with free-rigid boundaries. It is shown that a hexagonal cellular pattern and two-dimensional rolls are steady solutions of the set of model equations. The bifurcation diagram of these solutions is obtained together with their stabilities. Results of numerical simulations for the set of model equations illustrate the mechanism of the pattern formation.
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Sho Hosoda, Takuji Kawahara
Subject area: Fluid dynamics.
1994 Volume 63 Issue 1 Pages
111-120
Published: January 01, 1994
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Solutions of a perturbed Korteweg-de Vries equation are investigated both numerically and analytically for the case when the perturbation terms representing wave amplification and damping are given by the Hilbert transforms. Numerical simulations of the initial value problem indicate that ultimate states consisting of a row of interacting nearly identical pulses become irregular and non-steady even when the perturbation terms are sufficiently small. Individual pulses with equilibrium amplitude arising in numerical simulations can be explained by approximate quasi-stationary solutions derived by the energy balance relation. Certain special or approximate solutions are examined in terms of the pole expansion.
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Akira Matsuoka, Sumio Kogoshi, Makoto Katsurai
Subject area: The physics of plasmas and electric discharges.
1994 Volume 63 Issue 1 Pages
121-126
Published: January 01, 1994
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A winding law of a helical coil with higher harmonic modulation can produce a deep magnetic well because of a suitable vertical field formation. The sin, (nφ) modulation (n=1, , 2, , 3, , 4) on a L=1 helical coil makes magnetic surfaces resembling those of L=n helical coil at θ =0. Also it increases a magnetic ripple and rotational transform on a magnetic axis.
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Kazuaki Iwasa, Nobuyoshi Wakabayashi, Toshiro Takabatake, Hironobu Fuj ...
Subject area: Structure of liquids and solids; crystallography.
1994 Volume 63 Issue 1 Pages
127-134
Published: January 01, 1994
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Lattice modulations associated with magnetic order in Tm and Er were investigated by means of X-ray diffraction. Satellite peaks at wave vectors (0 0 2q
0) and (0 0 4q
0) were observed in Tm where q
0 is the fundamental wave number specifying the modulations of the magnetic moment along the hexagonal c-axis. The modulation amplitude, the atomic displacement along the c-axis, was estimated to be of the order of 10
-3, Å. No peak was detected at q
0. Peaks for 2q
0 and 4q
0 were observed also in Er. The amplitude of the 2q
0 modulations decreased with decreasing temperature below 30, K. A model based on the magnetoelastic interactions was constructed to calculate these amplitudes of lattice modulations. It involves the elastic, exchange and crystal field energies. The latter two magnetic energies were assumed to vary with the interatomic distance. This model, combined with the temperature variations of the magnetic moment, was found to reproduce the temperature dependence of the lattice modulations in Tm and Er. X-ray diffraction measurements were also made for UPdIn and NdCo
2Si
2. The magnetoelastic effects in these materials appear to be much weaker than those in Tm and Er.
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Kuo–Tung Liu, Jiang–Tsu Yu, Ssu–Hao Lou, Yng–H ...
Subject area: Structure of liquids and solids; crystallography.
1994 Volume 63 Issue 1 Pages
135-140
Published: January 01, 1994
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Two chemically inequivalent [N(CH
3)
3]
+ radical species produced via γ -irradiation were detected by EPR in the low-temperature, orthorhombic 1× √ 3 phase of [(CH
3)
3NH]CdCl
3. This indicates a twofold, static disorder of the [(CH
3)
3NH]
+ (TrM) ions. One of the radical species could be identified as originating from the “normal” TrM ions and the other from the “disordered” TrM ions. The EPR result also indicates that the population ratio of the “disordered” TrM ions relative to the “normal” TrM ions is temperature dependent; this ratio decreases with decreasing temperatures.
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Fuyuki Shimojo, Kozo Hoshino, Mitsuo Watabe
Subject area: Structure of liquids and solids; crystallography.
1994 Volume 63 Issue 1 Pages
141-155
Published: January 01, 1994
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The dynamical properties of liquid sodium at 380, K near the triple point are studied by means of a constant-temperature molecular dynamics simulation. For the interaction between ions, the effective pair potential based on the pseudopotential theory is adopted. The dynamical correlation functions are calculated for several wave vectors and the associated memory functions are obtained by solving the causality equation. The profiles of the memory functions are discussed in detail and some characteristic features are clarified. It is shown that the transport coefficients such as the diffusion constant D and the shear viscosity η are in agreement with those determined experimentally.
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Yoshimasa Nishio, Masafumi Shirai, Naoshi Suzuki, Kazuko Motizuki
Subject area: Lattice dynamics and crystal statistics.
1994 Volume 63 Issue 1 Pages
156-167
Published: January 01, 1994
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Lattice dynamics of 2H--NbX
2 (X=S, , Se) is studied by taking account of electron-lattice interaction derived microscopically on the basis of the realistic tight-binding bands fitted to the first-principles bands of 2H--NbX
2. Remarkable frequency renormalization of Σ
1 phonon mode around q=(2/3)ΓM is caused due to the characteristic wavevector and mode dependences of the electron-lattice interaction as well as the effect of Fermi surface nesting. It is shown that the short range force constant for neighboring X ions on different X-layers in the same X--Nb--X sandwich determines primarily whether lattice instability occurs (NbSe
2 case) or not (NbS
2 case). By using the electron-lattice interaction and the renormalized phonon frequencies obtained for 2H--NbS
2, the spectral function α
2F(ω ) is calculated and the superconducting transition temperature T
c is evaluated by solving the linearized Eliashberg equation. Renormalization of phonon frequencies due to the electron-lattice interaction raises T
c considerably and the obtained value of T
c agrees in order of magnitude with the experimental data. Effects of intercalation on T
c are also discussed.
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Mamoru Tanibayashi
Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1994 Volume 63 Issue 1 Pages
168-175
Published: January 01, 1994
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Evolution of the surface potential is calculated for NaCl crystals both in the intrinsic and in the extrinsic ranges. It is shown that its time constant is approximately given by the time for the faster species to move the Debye length by diffusion and the contribution of the slower species is negligible.
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Akinori Yamamoto, Torayuki Honmyo, Masao Kiyama, Teruya Shinjo
Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1994 Volume 63 Issue 1 Pages
176-183
Published: January 01, 1994
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Fine particles of α-FeO(OH) and β-FeO(OH) were prepared using
56Fe isotope and the surfaces of the particles were coated with extremely thin
57Fe(III) layers. Mössbauer results show that the Fe(III) ions in the top surface layer are involved in the magnetic order and the surface hyperfine fields rapidly decrease with increasing temperature. The exchange fields at surface sites, estimated from the temperature dependences of the hyperfine fields, are smaller than the bulk values in both cases. The decrease of exchange fields at the surface sites corresponds to the reduced number of neighboring magnetic ions at each site.
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Kazumoto Iguchi, Hong Su
Subject area: Electron states in condensed matter.
1994 Volume 63 Issue 1 Pages
184-190
Published: January 01, 1994
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We derive a new non-compact surface that is invariant under the trace map for the ternary Fibonacci lattice, which is constructed by a substitution scheme of three letters: A→ ABC, B→ A, C→ B. Here the trace map is given by a six-dimensional dynamical map. The invariant surface is of the fourth degree and exists in R
6. The existence of such surface is relevant to prove whether or not all the states in the spectrum belong to critical states, where the wave function is self-similar or fractal. At the center of the bands it has been known that there is a four cycle. It is proved from the four-fold symmetry of the manifold.
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Norikazu Tomita, Atsushi Ikawa, Hideo Fukutome
Subject area: Electron states in condensed matter.
1994 Volume 63 Issue 1 Pages
191-208
Published: January 01, 1994
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Electronic structures of low lying excited states in the 1D bond alternated Hubbard model are investigated using the resonating Hartree-Fock method. In homopolar states with the wave vector k=0, main units of quantum fluctuations (QF's) are two kinds of SDW neutral solitons whose centers are on a long bond and a short bond, respectively, and magnon fragments. QF's in ionic states contain charged defects such as SDW charged solitons and polarons as well as homopolar ones. The charge, spin and singlet pair correlation functions of the excited states show different correlation structures due to different QF's. The QF's are not spatially scaled but quantum motions of defects give constant correlation energy per site. The lowest singlet and triplet collective excitations have dispersions with gaps. Their QF's are k-dependent and scaled density wave like oscillations. A part of the QF's looks like unscaled SDW defects.
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Fumiko Yamaguchi, Mikio Eto, Kiyoshi Kawamura
Subject area: Electronic transport in condensed matter.
1994 Volume 63 Issue 1 Pages
209-222
Published: January 01, 1994
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An analytical expression for the Green function is derived for an independent electron which moves in a one-dimensional space with a double-square potential barrier. A perturbation theory is constructed for a system of interacting electrons and the effect of the Coulomb interaction on resonant tunneling phenomena is studied. Solving numerically the Dyson equation of the one-dimensional system in the Hartree approximation, the self-consistent Green function is computed, from which the transmission probability through the barrier and the density of states within the well region have been calculated and analyzed. The impurity Anderson model is examined in comparison with the present model of more fundamental nature. Our method is expected to be applied to studies of other types of interaction in an inhomogeneous system in quasi-one-dimension.
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Yoshimasa Nishio
Subject area: Electronic transport in condensed matter.
1994 Volume 63 Issue 1 Pages
223-228
Published: January 01, 1994
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By using the electron-lattice interaction, the phonon frequencies and the phonon's polarization vectors obtained microscopically on the basis of the realistic band structure of 2H--NbS
2, the electrical and thermal resistivities of 2H--NbS
2 are calculated as functions of temperature by solving the Boltzmann equation. It is shown that the energy dependence of the transport spectral functions reflects strongly the effect of the renormalization of phonons as well as the geometry of the Fermi surfaces. The calculated electrical and thermal resistivities agree semi-quantitatively with the observed results.
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Mikio Eto
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1994 Volume 63 Issue 1 Pages
229-238
Published: January 01, 1994
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Electronic collective modes of an ultrathin film of transition metal dicalcogenides are investigated based on models in which the interlayer transfer integrals are neglected. First we study the two-dimensional plasmons in the film consisting of the different materials from layer to layer. Then, taking into account the intralayer polarization effect in the c direction, we show that the bulk-plasmon-like modes can appear in the quasi-two-dimensional systems. Analytical expression of the dispersion relation is given in the long wave limit while numerical calculations are performed for the whole range of wavelength in the random phase approximation.
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Seiya Kumada, Seiichiro Suga, Ayao Okiji
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1994 Volume 63 Issue 1 Pages
239-246
Published: January 01, 1994
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Theoretical study is made for the dispersion relation and for the spectra of intersubband elementary excitations in the quasi-two dimensional electron gas of GaAs/AlGaAs quantum well. Density-density correlation functions appearing in expressions for transition probabilities are calculated by means of the perturbation expansion with respect to the Coulomb interactions between electrons in the conduction subbands. From the calculated results, at long-wavelength limit the effects of the attractive Coulomb interactions between electrons and holes on the energy shift of the collective excitations from the single-particle excitations are shown to be comparable to the depolarization effects. The peak positions of the collective charge- and spin-density excitations in spectra are in qualitative agreement with the recent experimental findings.
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Toshimitsu Fujita, Wataru Aoyama, Kazushige Machida, Tetsuo Ohmi
Subject area: Superconductivity.
1994 Volume 63 Issue 1 Pages
247-255
Published: January 01, 1994
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Possible vortex lattice structures for UPt
3 are investigated for the superconducting order parameter described by a triplet pairing function belonging to a one-dimensional representation. The phase diagram in H vs T for H parallel to the hexagonal c-axis is analyzed. Several observed characteristics, including the existence of four second order transition lines and a tetracritical point are reproduced to confirm the identification of the above pairing state for UPt
3, which enables us to fully characterize various phases in the presence of H. Additional first order transitions at low H is suggested to occur for an appropriate parameter region.
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Tetsuo Matsui
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
256-263
Published: January 01, 1994
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The antiferromagnetic s=1/2 Heisenberg spin model in one dimension is analyzed by a variational Hamiltonian in terms of Jordan-Wigner fermions. Some results are compared with those of modified bosonic spin-wave theory. The fermionic quasi-particles (spinons) reproduce the “spin-wave” excitations of des Cloizeaux and Pearson with good accuracy.
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Katsurou Hanzawa
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
264-270
Published: January 01, 1994
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For the antiferromagnets of insulating cuprates which are parent compounds of high-T
c copper oxides, it is shown that an anisotropic “direct” exchange interaction (pseudo-dipolar interaction) is responsible for the easy-plane anisotropy which makes spins lie in CuO
2 planes. This argument is confirmed by showing that the same origin is responsible for the anisotropy in a related ferromagnetic compound, K
2CuF
4.
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Seishi Takagi, Kenji Nakao, Kazumi Nakatsu
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
271-282
Published: January 01, 1994
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An organic ion-radical salt, 3, 3'-diethyl-4, 4'-dimethyl-2, 2'-thiazolocyanine-[TCNQ]
2, is synthesized and its crystal structure and electronic properties are investigated. The salt forms triclinic crystal in the space group P\bar{1} with a=13.153(4), b=18.314(5), c=7.792(2), Å, α =107.21(3), β =103.60(4), γ =77.75(3)° and Z=2. The electric conduction of single crystals is anisotropic and shows semiconductive temperature dependence. The intrinsic spin-susceptibility of the salt shows a broad maximum around 265, K and decreases to zero below 15, K. A single ESR absorption is observed for a single crystal and its linewidth strongly depends on the temperature and the direction of external magnetic field. These electronic properties are discussed on the basis of the peculiar crystal structure of the salt.
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Hirofumi Wada, Naoki Shimamura, Masayuki Shiga
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
283-288
Published: January 01, 1994
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Low temperature specific heat and electrical resistivity have been studied for the Laves phase compounds Sc
1-xTi
xFe
1.95, which show the ferromagnetic to ferromagnetic (F-F) transition with increasing temperature at around x=0.7. It is shown that the electronic specific heat coefficient, γ, and the coefficient of T
2 term in the resistivity, A, show a maximum at the critical concentration for the onset of Fe moments at the 2a site. The correlation between γ and A are discussed in terms of spin fluctuations. A small but visible anomaly was observed in the specific heat curve of Sc
0.3Ti
0.7Fe
1.95 at 100, K due to the F-F transition. The origin of the entropy change associated with the F-F transition is also discussed.
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Isao Yamada, Naoshi Kato
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1994 Volume 63 Issue 1 Pages
289-297
Published: January 01, 1994
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The compound KCuF
3 is known to form antiferromagnetic quantum linear chains in spite of its pseudo-cubic crystal structure, and type-A collinear magnetic ordering with the spins lying in the c-plane has been accepted so far. However, recent electron paramagnetic resonance studies revealed the existence of the ∑
ij, d
ij· (S
i× S
j) interaction with d
ij⊥ c-axis between nearest-neighbour spins along the c-axis, but the direction of d
ij in the c-plane is still unknown. To clarify the direction of d
ij in the c-plane, antiferromagnetic resonance experiments were conducted at 4.2, K, which is far below T
N=39, K, using an X-band spectrometer. Analysis of the resonance field having a fourfold symmetric change in the c-plane revealed that d
ij//[100]
p which are orthogonal to each other in the c-plane. Owing to these d
ij, spins are canted in their directions and are divided into eight sublattices.
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Ryuji Abe, Masakiyo Horioka, Izumi Sakumiya
Subject area: Dielectric properties and materials.
1994 Volume 63 Issue 1 Pages
298-305
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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The data of dielectric dispersion for trimethyleneglycol-water mixtures are examined precisely above a certain temperature, T
a, where they deviate from the universal scaling curve. The tendency of deviation is compared with those obtained from various relaxation processes. It is clarified from the analysis that any system of supercooled trimethyleneglycol-water mixture is of polydispersive nature at considerably higher temperatures than T
a, but it increases the high frequency component of dielectric dispersion and loses the polydispersive nature with approaching T
a. It is also ascertained that the deviation from the universal scaling curve at higher frequencies than ν
p changes from downward one to upward one near T
a and then the data of ε''(ν ) fall on accurately the universal scaling curve at and below T
a.
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Atsushi Mori, Yosuke Kayanuma, Makoto Nakazawa, Akio Kotani
Subject area: Dielectric properties and materials.
1994 Volume 63 Issue 1 Pages
306-313
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Theory of the La 2p3d3d resonant Auger electron spectroscopy for insulating La-compounds is presented for the process that the incident photon is tuned to resonate with 2p→ 5d or the continuum (6s, , 6d, · · · ε s, , ε d) transition and the Auger electron due to the 2p3d3d Auger transition is observed. The theory is based on the impurity Anderson model that takes into account the hybridization of the La 4f-level with the anion valence band and also the effect of the core hole potential for the 4f- and 5d-electrons. It is shown that the core exciton effect due to the Coulomb attraction between the core holes and the photoexcited 5d-electron plays an important role in determining the spectral features of the Auger transition.
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Arisato Ejiri, Akira Hatano, Kazumichi Nakagawa
Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 Volume 63 Issue 1 Pages
314-325
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Relative photoelectric yield spectra of thin films in KCl, KBr and RbCl are investigated in the photon energy 7, eV--40, eV range at 80, K as well as at room temperature. Several new characteristics of the spectra due to the thin film specimens and due to the lower temperature are observed. It is revealed that the yield spectra dominantly reflect the photo-absorptions modified by the inelastic electron-electron scattering in the valence excitation region and by the Auger process especially in the core excitation region. A large yield peak due to the next deeper core level K
+3s or Rb
+4s is newly identified in a photon energy range of 30--40, eV. Interband thresholds of the yield spectra are observed and the electron affinities are derived.
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Haruya Shiba, Yukio Inoue, Masanobu Haraguchi, Masuo Fukui
Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 Volume 63 Issue 1 Pages
326-334
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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The dispersion relations of surface polaritons (SP's) with a real frequency and a complex wavenumber in the so-called Otto and Kretschmann geometries have been numerically evaluated. Under a certain condition, SP's fields increase propagating along the surface or increase exponentially going into the prism. It is found that these curious results are induced by the existence of a prism and can be interpreted based on information about electric (or magnetic) fields in the respective layers. Various types of wavenumber, e.g. the wavenumber giving a maximum SP field, are evaluated.
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Toru Tsujibayashi–Kishigami
Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 Volume 63 Issue 1 Pages
335-346
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Luminescence of free excitons (FEs) and self-trapped excitons (STEs) in alkali iodide crystals are investigated under excitation in the n=1 exciton absorption region using a narrow-band UV laser. Experimental results support the identification that the prominent peaks of the FE luminescence spectra of KI and RbI are triplet emission and that of NaI is singlet emission. It is clarified that most singlet FEs in KI and RbI are scattered to the triplet state during the relaxation in the n=1 exciton band. The accumulation of FEs on the triplet state induces the decrease in the intensity of singlet STE luminescence. On the other hand, the scattering rate of the singlet FE to the triplet FE state in NaI is found to be small. The relation between scattering rate of FE and the magnitude of the exchange energy relative to the LO phonon energy is discussed.
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Yasuhisa Tezuka, Shik Shin, Takehiko Ishii, Takeo Ejima, Shoji Suzuki, ...
Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 Volume 63 Issue 1 Pages
347-357
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Photoemission and bremsstrahlung isochromat spectra have been measured on TiO
2 (rutile) and SrTiO
3. The magnitudes of the fundamental band gaps estimated from the combined spectra agree well with the results of the photoabsorption and the energy-band calculations. The profiles of the observed spectra do not reveal the fine structure expected to occur in the density-of-states curves obtained by the energy band calculations, suggesting the existence of a mechanism to smear out the fine structure considerably. The combined spectra are used to interpret the charge-transfer-type satellite manifest in the core-level spectra. For 3s photoemission, satellite features ascribed to the configuration interaction between the 3s3p
6 and 3s
23p
43d states in the atomic notation are also observed.
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Baoping Zhang, Yasuhiro Shiraki, Ryoichi Ito
Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 Volume 63 Issue 1 Pages
358-362
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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The exciton phonon interaction in AlGaAs/GaAs and InGaAs/GaAs single quantum wells (QWs) is studied through the temperature dependence of the oscillator strength of the zero-phonon-line e1-hh1 excitonic transition. It is found that the main phonon modes involved in the exciton phonon interaction are different between these two systems: the confined phonons in the AlGaAs/GaAs QWs and the three-dimensional phonons in the InGaAs/GaAs QWs.
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Keizo Horiuchi
Subject area: Thermal properties of condensed matter.
1994 Volume 63 Issue 1 Pages
363-364
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Haruhiko Kuroe, Kenji Kobayashi, Tomoyuki Sekine, Masashi Hase, Yoshit ...
Subject area: Thermal properties of condensed matter.
1994 Volume 63 Issue 1 Pages
365-366
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Tsuyoshi Ueta
Subject area: Electronic transport in condensed matter.
1994 Volume 63 Issue 1 Pages
367-368
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Yoshiya Adachi, Motoyoshi Yuzuri, Takejiro Kaneko, Shunya Abe, Hajime ...
Subject area: Magnetic properties and materials.
1994 Volume 63 Issue 1 Pages
369-370
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Fumio Maruyama, Hiroyuki Nagai, Kengo Adachi
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1994 Volume 63 Issue 1 Pages
371-372
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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Hiroyuki Uehara, Masaru Komukae, Minoru Sumita, Toshio Osaka, Yasuharu ...
Subject area: Dielectric properties and materials.
1994 Volume 63 Issue 1 Pages
373-374
Published: January 01, 1994
Released on J-STAGE: October 01, 1999
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