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Yoshimasa Matsuno
1991 Volume 60 Issue 10 Pages
3197-3199
Published: October 15, 1991
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The propagation of nonlinear Alfvén waves in a compressible viscous fluid is described by a nonlinear diffusion equation (I. Nakata: J. Phys. Soc. Jpn.
60 (1991) 1952). We show that it reduces to a nonlinear ordinary differential equation of the first order by introducing an appropriate similarity variable. The numerical solutions of the reduced equation are presented together with asymptotic solutions for both small and large Reynolds numbers.
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Iwao Mogi, Susumu Okubo, Yasuaki Nakagawa
1991 Volume 60 Issue 10 Pages
3200-3202
Published: October 15, 1991
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Growth patterns of silver metal leaves from AgNO
3 solutions were investigated in a high magnetic field of 8 T as experimental research of diffusion-limited aggregation (DLA) with magnetohydrodynamic drifts of ions. Silver metal leaves grew into a typical DLA form with the fractal dimension of 1.62 in the absence of magnetic fields, and they grew into a dense radial form in the field of 8 T, where the crossover in the fractal dimension from 1.69 to 2 was observed with increasing length scale.
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Masayoshi Nagata, Tsuyoshi Masuda, Shingo Naito, Tadao Uyama
1991 Volume 60 Issue 10 Pages
3203-3206
Published: October 15, 1991
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The formation and sustainment of a spheromak plasma with bias flux has been demonstrated successfully by “DC” or “electrostatic” helicity injection. The experimental results show that, as the helicity injection rate is increased, the self-generated toroidal plasma current and the toroidal flux increase significantly. By examination of the contours of poloidal flux of the sustained spheromak, we have verified the formation of the magnetic configuration with the external bias flux linking the region of the closed flux surfaces. In addition, it has been found that the λ
spk≡
j⁄⁄⁄
B value of the sustained spheromak configurations with a small amount of the closed flux in the flux conserver has been affected by the ratio of the electrode current to the bias flux.
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Kwang-Sei Lee, Kyeong-Lim Kim
1991 Volume 60 Issue 10 Pages
3207-3210
Published: October 15, 1991
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The dielectric properties of TlH
2AsO
4 powder pellet are investigated over the temperature range from 80 to 433 K. With respect to the form of the temperature dependence of complex dielectric constant, TlH
2AsO
4 crystal shows much the same characteristics as with the TlH
2PO
4 crystal. The results are indicative of a first-order antiferroelectric phase transition at 250.5 K (the lower phase transition point,
TL) with thermal hysteresis of 1.4 K, and of a second-order ferroelastic phase transition at about 390 K (the upper phase transition point,
TU).
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Yuichi Akahama, Mototada Kobayashi, Haruki Kawamura
1991 Volume 60 Issue 10 Pages
3211-3214
Published: October 15, 1991
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High-pressure X-ray diffraction study on the electronic
s-
d transition in IVa transition metal Zr has been carried out up to 68 GPa. The successive structural transitions of hcp-hexagonal-bcc were observed at 6.7 GPa and 33 GPa, respectively. An isostructural transition was also observed in the bcc phase around 56 GPa. The values of the isothermal bulk modulus,
K0, and the pressure derivative of
K0,
K0′, for the hexagonal phase were calculated to be 121 GPa and 1.69, respectively. Abnormally small
K0′ suggests softening in the pressure-volume curve. The atomic volume of the bcc-Zr at the transition pressure of 33 GPa agreed with that of the bcc-Nb at zero pressure. These results suggest that the
s-
d transition of Zr metal progresses at each pressure and is complete with an isostructural transition at 56 GPa.
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Yoshihiro Ishibashi
1991 Volume 60 Issue 10 Pages
3215-3217
Published: October 15, 1991
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Intensity oscillation of reflection high-energy electron diffraction (RHEED) is discussed under the light of an analytical solution obtained for polynuclear growth processes based on the Kolmogorov-Avrami model. According to the model, the RHEED intensity oscillations persist both for the one- and the two-dimensional cases, implying a steady growth.
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Fusayoshi J. Ohkawa
1991 Volume 60 Issue 10 Pages
3218-3221
Published: October 15, 1991
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The Hubbard model with strong correlation is examined. The mean-field approximation (MFA) based on the best single-site approximation (SSA) is rigorous in the limit of high dimension of
d=+∞. The best SSA is reduced to solving the Anderson model. The ground state is a heavy-electron liquid, presumably superconducting, in the weak-coupling regime, which is approximately defined by
g≈
J(
Q)⁄4
TK<1 with
J(
Q) being the maximum value of exchange interactions and
TK the Kondo temperature to show the energy scale of heavy electrons. In the strong-coupling regime defined by
g>1, on the other hand, the ground state is a MFA-type antiferromagnetic state.
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Arisato Kawabata
1991 Volume 60 Issue 10 Pages
3222-3225
Published: October 15, 1991
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Electron transport through a quantum dot is discussed from the point of view of the Friedel sum rule. When an odd number of electrons are in the dot, the localized moment may be formed because of the Coulomb repulsion between the electrons. In this situation, it is predicted that the transmission probability of an electron through the dot is almost unity if the temperature is lower than the Kondo temperature, i.e., the characteristic energy of the spin fluctuations divided by Boltzmann constant.
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Kiichi Okuda, Shuichi Kawamata, Satoru Noguchi, Nobutaka Itoh, Kazuo K ...
1991 Volume 60 Issue 10 Pages
3226-3229
Published: October 15, 1991
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Magnetic anisotropy of layered superconducting oxide Bi
2Sr
2CaCu
2O
8+δ single crystal was investigated by torque measurements at 77 K. A hysteresis loop with a sharp cusp was found for the magnetic fields below about 6 kOe close to the
ab-plane. It can be satisfactorily explained by assuming that the component of diamagnetic moment perpendicular to the
ab-plane is induced by the applied external field. In fact, the field and angular dependence of the cusp is ruled well by the relation
H cos θ=
HcP, where
HcP is the critical field perpendicular to the
ab-plane at which the flux-pinning decreases abruptly with increasing field.
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Hiroshi Ito, Masashi Watanabe, Yoshio Nogami, Takehiko Ishiguro, Tokut ...
1991 Volume 60 Issue 10 Pages
3230-3233
Published: October 15, 1991
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The Ginzburg-Landau coherence lengths are determined from the temperature dependence of the magnetization by fitting measured results with the renormalization theory of the fluctuation developed for layered superconductors. The derived interlayer coherence lengths are 6±2 Å and 3.2±0.5 Å for κ-(BEDT–TTF)
2Cu[N(CN)
2]Br and κ-(BEDT–TTF)
2Cu(NCS)
2, respectively, which are remarkably shorter than the interlayer spacing. It is also found that these coherence lengths are virtually unaffected by isotope substitution in BEDT–TTF molecules.
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Chiaki Uyeda, Tetsuya Takeuchi, Akio Yamagishi, Muneyuki Date
1991 Volume 60 Issue 10 Pages
3234-3237
Published: October 15, 1991
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The orientations of diamagnetic mineral grains in magnetic fields are observed, for the first time, in suspensions of clay minerals such as talc, kaolinite and sericite. The minerals consist of two-dimensional crystal layers which produce intrinsic diamagnetic anisotropy,
Δχ, in the unit cell. In the case of talc suspension with the average diameter of φ 2.4 μm and the thickness of 0.2 μm, the grains show full orientation in a magnetic field of less than 0.5 T. As the size of the grains becomes smaller, full orientation is achieved with higher fields. This size dependence occurs because the field-induced anisotropic energy of a grain is proportional to
NΔχ, where
N is the number of unit cells in the grain.
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Shinichi Itoh, Hironobu Ikeda, Takashi Suzuki, Yasuo Endoh
1991 Volume 60 Issue 10 Pages
3238-3241
Published: October 15, 1991
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The kinetics of the disordering process from an initial long-range ordered state to a final microdomain state has been elucidated with a two-dimensional dilute Ising antiferromagnet, Rb
2Co
0.6Mg
0.4F
4. The present results have revealed that the temporal change in the order of ramified clusters obeys a logarithmic law, at low temperatures, independent of both the temperature and the strength of the external field. This fact indicates that the kinetics of disordering is governed by a random magnetic field.
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Fumihisa Suzuki, Kazuhiro Takayama, Kazuyuki Watanabe, Chikara Ishii
1991 Volume 60 Issue 10 Pages
3242-3244
Published: October 15, 1991
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Thermodynamic properties of the bond-diluted Heisenberg ferromagnet in two dimensions are studied within the framework of the modified spin-wave theory. It is shown that the renormalized exchange (2
m−1)
J,
m being the bond concentration, appears in place of
J in the expressions of various thermodynamic quantities in the perfectly bonded case, consistent with the result obtained in the Monte Carlo calculation at low temperatures.
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Makoto Iwata, Yoshihiro Ishibashi
1991 Volume 60 Issue 10 Pages
3245-3248
Published: October 15, 1991
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The temperature dependence of dielectric dispersion in [N(C
2H
5)
4]
2ZnCl
4 single crystal, whose transition temperature is 220 K, was measured in the temperature range from about 200 K to 300 K. A notable dispersion is found only along the
a-axis. The relaxation time, which increases as the transition temperature is approached from above, can be analyzed through the Arrhenius plot, assuming a simple activation energy.
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Kousuke Yakubo, Tsuneyoshi Nakayama, Humphrey J. Maris
1991 Volume 60 Issue 10 Pages
3249-3259
Published: October 15, 1991
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This paper analyses a new numerical method, based on mechanical resonance to extract pure vibrational eigenmodes for very large systems. This method can be used for systems containing as many as ∼10
6 particles, which are too large to be treated by conventional numerical methods. In addition, this algorithm can easily be vectorized for implementation on an array-processing supercomputer. A formula is given to judge the accuracy of the eigenmodes and eigenfrequencies that are found. In addition a discussion is given of how to make the most efficient choice for two key parameters entering into the algorithm, namely the driving time interval
t and the number of iterations
p.
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Masao Nomura
1991 Volume 60 Issue 10 Pages
3260-3270
Published: October 15, 1991
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Quantum matrix algebras
suq(2) are formulated in terms of the co-variant and the contra-variant spinors (
a+,
b+), (
a,
b) subject to linear transformations of
SUq(2),
a′
+=
a+x+
b+v,
b′
+=
a+u+
b+y,
a′=
ax*+
bv* and
b′=
au*+
by*, where
x,
u,
v,
y with and without * are non-commutative objects. Commutation relations, which are quadratic in spinor components, are determined with the following conditions: (i) invariance under the linear transformations of
SUq(2) and (ii) uniqueness of scalar and co-variant vectors made of spinor components. Commutation relations for
A+(
j′
m′;
a+,
b+) and
A+(
j″
m″;
e+,
f+), where
A+(
j″
m″;
e+,
f+) is the
m″-component of rank-
j″ co-variant tensor written as polynomials in components of spinor (
e+,
f+), give Zamolodchikov-Zamolodchikov equations with (2
j′+1)×(2
j″+1) universal
R matrix elements of
suq(2). The (2
j+1)-dimensional matrix {
dmkJ(
a+,
b+,
e+,
f+)} is presented which is a quantized quantum
d-function.
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Masakazu Ichiyanagi
1991 Volume 60 Issue 10 Pages
3271-3288
Published: October 15, 1991
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We continue our attempt to develop a nonequilibrium statistical mechanics using an operator algebraic structure of density matrix of a closed system. After applying the time-smoothing operation, which is originally due to Kirkwood, we obtain an initial density matrix which is almost periodic with respect to an initial time
t0 and describes a passive state. Based on the relative entropy formula, we consider extra dissipation (beyond the spontaneous constant dissipation in the stationary state) due to the mechanical perturbations. We examine the existence of a fluctuation-dissipation theorem for nonequilibrium stationary states and prove an analogous basic theorem to the fluctuation-dissipation theorem near equilibrium states.
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Koh Wada, Naotosi Watanabe, Tetsuya Uchida
1991 Volume 60 Issue 10 Pages
3289-3297
Published: October 15, 1991
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The critical exponents of the bond percolation model are calculated in the
D(=2, 3, …)-dimensional simple cubic lattice on the basis of Suzuki’s coherent anomaly method (CAM) by making use of a series of the pair, the square-cactus and the square approximations of the cluster variation method (CVM) in the
s-state Potts model. These simple approximations give reasonable values of critical exponents α, β, γ and ν in comparison with ones estimated by other methods. It is also shown that the results of the pair and the square-cactus approximations can be derived as exact results of the bond percolation model on the Bethe and the square-cactus lattice, respectively, in the presence of ghost field without recourse to the
s→1 limit of the
s-state Potts model.
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Taro Nagao, Miki Wadati
1991 Volume 60 Issue 10 Pages
3298-3322
Published: October 15, 1991
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In the theory of level statistics, the statistical properties of energy levels are obtained from the correlation functions of random matrix ensembles. A class of matrix ensembles, which are related to classical orthogonal polynomials, has extensively been investigated in the case of complex hermitian random matrices. We systematically evaluate the correlation functions of the random matrix ensembles in all the three cases of complex hermitian, real symmetric and self-dual quaternion random matrices.
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Gajendra K. Johri, Shashi K. Pathak, Pankaj Gupta
1991 Volume 60 Issue 10 Pages
3323-3326
Published: October 15, 1991
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Microwave linewidth parameters for foreign broadening of CH
3 81Br JK 0, 0→1, 0 of the C
3v symmetry perturbed by O
2 were calculated considering the dipole-quadrupole, quadrupole-quadrupole and dispersion interactions. Two interpolation schemes for weak and strong molecular collisions in the framework of perturbative theory were used for the calculation and results were compared. It has been found that reduction in the distance of closest approach for strong collisions significantly affects the contribution of various interactions and the values of resonance functions in comparison with the effects for weak collisions.
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Kunizo Onda, Masahiro Iwai, Takashi Wada
1991 Volume 60 Issue 10 Pages
3327-3339
Published: October 15, 1991
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Vibrational transition processes of H
2 molecule in the electronic ground state by H atom impact are investigated theoretically by solving vibrational close coupling equations under the rotational IOS approximation. Integrated cross sections for non-reactive vibrational transitions from the initial vibrational states within 0≤
v≤4 to all the energetically accessible final vibrational states are calculated at the impact energy below the dissociation energy of H
2 molecule. The cross sections for vibrational multiple quantum transitions have the same order of magnitude as the cross section for a single quantum transition. It is confirmed that the multi-quantum vibrational transitions proceed step by step through the vibrational matrix elements
Vv,v±1 of interaction potential. It is found that a dip part of the vibrational matrix elements induces vibrational transitions and a positive part makes little effect to these transitions.
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Susumu Ikeda, Noboru Watanabe, Kazuhiko Inoue, Yoshiaki Kiyanagi, Akir ...
1991 Volume 60 Issue 10 Pages
3340-3350
Published: October 15, 1991
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A high energy-resolution neutron spectrometer with large mica mirrors, LAM-80ET, has been constructed at National Laboratory for High Energy Physics in Japan (KEK). The highest resolution achieved with this spectrometer is 1.2 μeV. In order to examine the capability of the spectrometer, the rotational tunnelling of the methyl group in 4-methyl pyridine N-oxide (N-oxy γ-picoline) has been measured. Using the (004) reflection of the mica mirrors, we have clearly observed four peaks at ε=60, 115, 190 and 274 μeV. Measurements of the
Q-dependence of these tunnelling peaks show that the tunnelling potential may be three-fold. It is also shown that the line width of tunnelling modes and the spin conversion at
T>5 K are derived by the libron-phonon process with
EL=30–40 K.
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Tomejiro Yamagishi
1991 Volume 60 Issue 10 Pages
3351-3358
Published: October 15, 1991
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Energetic trapped particles bounce resonance excitation of magnetohydrodynamic (MHD) ballooning mode is studied by using the averaged ballooning mode equation in a tokamak with the circular cross section. The bounce resonance contribution of trapped energetic particles is found to play an important role in the outer inertial region of the ballooning mode perturbation, and destabilizes the ballooning mode when the shear effect is not strong. The inhomogeniety of a model slowing down energetic particle distribution in velocity space, ∂
F⁄∂
E<0, is effective to stabilize the bounce resonant mode.
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Yi Ping Wang
1991 Volume 60 Issue 10 Pages
3359-3366
Published: October 15, 1991
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The equilibrium and the stability of flux-core spheromak plasma with finite pressure are analyzed and the effects of the flux core are investigated. CTCC-II spheromak is used as the FC (Flux Conserver) model of the flux-core spheromak and the MHD equilibrium configurations are determined numerically. By use of these configurations, it is shown that the magnetic field profile of ordinary spheromak transits into the field profile where the toroidal magnetic field decreases monotonously with the distance from symmetric axis, when λ decreases from λ
0. Here, λ is the ratio of the flux-core current to the flux of the flux core, and λ
0 is the lowest eigenvalue of the Grad-Shafranov equation when plasma is bounded all by a conducting wall. In midway of this transition, the plasma confinement is shown to be worsened. The profiles of the safety factor
q and d
V⁄dψ also show characteristic variation for the transition. This transition characterizes the flux-core spheromak from other reactors.
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Reiji Sugaya
1991 Volume 60 Issue 10 Pages
3367-3385
Published: October 15, 1991
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The velocity space diffusion equation which describes distortion of the velocity distribution function due to resonant wave-wave scattering of electromagnetic and electrostatic waves in a homogeneous magnetized plasma is derived from the Vlasov-Maxwell equations by perturbation theory. The velocity space diffusion coefficient and the nonlinear wave-wave coupling coefficient which are expressed by three-order tensors in the rotating and Cartesian coordinates are transformed into simple and convenient forms in the Cartesian coordinates. By electrostatic approximation the kinetic equations can be also applicable to the case where the three waves are electrostatic altogether or partially electrostatic. The conservation laws for total energy and momentum densities of waves and particles are verified.
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Masahiro Nakagawa, Koichiro Kobayashi
1991 Volume 60 Issue 10 Pages
3386-3391
Published: October 15, 1991
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We put forward a diffusion-limited aggregation model with a fractional Brownian motion. The trajectory of a moving particle is controlled by the midpoint displacement method. The effects of such a trajectory of the moving particle on the aggregation clusters are investigated in detail evaluating the fractal dimensionality. The present result is compared with the earlier theoretical prediction by Honda
et al. over
dw=1∼2, where
dw is the fractal dimension of the trajectory. Consequently the fractal dimension of the clusters
D was found to be well evaluated by the relation,
D={
d2+(
dw−1)}⁄{
d+(
dw−1)}, where
d is the Euclidean dimension of the embedding space.
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Kêitsiro Aizu
1991 Volume 60 Issue 10 Pages
3392-3399
Published: October 15, 1991
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Transitions from prototypic phases to simultaneously incommensurate and ferroelectric phases are possible even when the number of (proper) order parameters is one. A case is investigated where the prototype point group is
mmm and the (proper) order parameter belongs to the zero-wavenumber irreducible representation,
B2u. A subsidiary order parameter, which is not soft like the proper one but moderately hard, is taken into account; it belongs to
B1u. The
B2u and
B1u order parameters can be identified with polarization components
Py and
Pz respectively. The free energy function contains term
Py (
Pz∂
zPy−
Py∂
zPz). This term can generate a phase incommensurate in the
z direction and ferroelectric in the
y direction. Sufficient conditions are found out for this ferroelectric incommensurate phase to outrival other ferroic phases in succeeding the prototypic phase.
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Kôichirô Nojima
1991 Volume 60 Issue 10 Pages
3400-3408
Published: October 15, 1991
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By extending the nonlinear sigma model to the semi-infinite geometry, the correlation function exponents η
⁄⁄, η
⊥ of the ordinary transition are estimated to the order of ε
2(ε=
d−2).
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Kenji Tashiro, Takuro Tsuzuku
1991 Volume 60 Issue 10 Pages
3409-3414
Published: October 15, 1991
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In succession to the previous study on the low temperature specific heat of ICl-graphite intercalation compounds below 5 K, a theoretical analysis has been made on the data obtained in the higher temperature range up to 300 K using a semi-continuum model similar to that originally proposed by Komatsu and Nagamiya for graphite. The specific heat of the stage-1 compound is concluded to consist of four components which are due to in-plane mode phonons in both of graphite and ICl layers, and acoustic and optical longitudinal phonon waves either in the
c-direction. The data for higher stage compounds are reproducible just by summing up fractional contributions of the graphite part and the compound part.
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Masatoshi Saito
1991 Volume 60 Issue 10 Pages
3415-3425
Published: October 15, 1991
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The electrical conductivities and transport numbers of the solid solution (Ag
xCu
1−x)Br have been measured as a function of temperature and composition. An attempt to determine the partial conductivities and activation energies for mobile ions is made from these results. The estimated enthalpies of formation and migration for Ag
+ and Cu
+ ions show an exponential decrease with increasing amount of Cu
+ into AgBr lattice. The lowering is attributable to the lattice expansion by the occupation of Cu
+ at the interstitial sites. The effect of exponential decrease in the formation enthalpy is to allow a rapid growth in the concentration of interstitials around the composition of χ\simeq0.85. This result is consistent with structural data derived by X-ray diffraction.
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Susamu Taketomi, Hiromasa Takahashi, Nobuyuki Inaba, Hideki Miyajima
1991 Volume 60 Issue 10 Pages
3426-3432
Published: October 15, 1991
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Light absorption spectra of magnetite fine particles of about 7 nm in mean diameter dispersed in magnetic fluid were measured as functions of photon energy,
E, from 0.5 eV through 1.8 eV and of particles’ temperature from 294 K up to 383 K. The light absorption coefficient α of the particles is smaller than that of the bulk magnetite. With increasing temperature, α decreases for
E lower than 1.378 eV, but it increases for
E higher than 1.378 eV. In addition, the spectra are shifted towards higher energy region by 0.136 eV compared with that of the bulk magnetite. If concentration of oscillator strengths on the bottom of 4s band of iron ion is assumed, the energy shift can be interpreted in terms of the quantum size effect of the fine particles, and the effective mass of the 4s electron is evaluated to be 0.37 times as much as that of a bare electron.
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Shoji Yamamoto, Akira Takahashi, Hideo Fukutome
1991 Volume 60 Issue 10 Pages
3433-3448
Published: October 15, 1991
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The electronic structure of the one dimensional Hubbard model is calculated by the resonating Hartree-Fock (HF) method. Solitons in the spin density wave (SDW) order parameter (OP) make translational bands with a lot of high harmonics. Their effective masses are about 0.1 of the electron mass, so that they are potentially good charge or spin carriers. We consider diradical and zwitterionic breathers, which consist of a neutral and charged soliton-antisoliton pair, respectively, making quantum translational and breathing motions, as local quantum fluctuations in the SDW in the half filled case. The stabilization of the ground state by the resonationg breathers amounts to 76.5% (
U=3) and 70.1% (
U=4) of the correlation energy. This is better than the result of the Gutzwiller method. The fluctuations by breathers explain the rapid decrease of the spin correlation function in short distances and give also low energy excited states with the symmetries and energetic ordering
3B<
1A<
1B that are characteristic in polyenes.
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Takashi Yanagisawa
1991 Volume 60 Issue 10 Pages
3449-3459
Published: October 15, 1991
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We present a diagonalization study of the two-impurity Anderson model. We explore the competition between the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Over the entire range of the exchange coupling
J between two magnetic impurities, we evaluate the susceptibilities. We find that the two-impurity state smoothly changes from a triplet-like state to a singlet-like one with the increase of
J; there is a smooth crossover from small into large coupling. In order to study this further, we consider the Anderson model with only even-parity-mixing term. In this model, there is a critical point
Jc; the localized spins form a triplet for
J<
Jc and a singlet for
J>
Jc. We also discuss, in the numerical diagonalization and a variational theory, the metamagnetic transition induced by the antiferromagnetic interactions in the two-impurity system.
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Masahiro Inoue, Tadashi Takemori, Hiroshi Miyazaki
1991 Volume 60 Issue 10 Pages
3460-3474
Published: October 15, 1991
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Dynamical trace-map of the tight-binding model is investigated by generalizing the stacking rule of the Fibonacci lattice. The recurrence relation is defined by
D(
n+1)=
D(
n)
pD(
n−1)
q for positive integers
p and
q, where
D(
n) is the atomic sequence of the
n-th generation. The structure of the dynamical trace-map is analyzed in terms of the invariant and the quasi-invariant of the map. Characteristic features of the wave function, local density of states and the average density of states are analyzed.
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Yoshiaki \={O}no, Tamifusa Matsuura, Yoshihiro Kuroda
1991 Volume 60 Issue 10 Pages
3475-3500
Published: October 15, 1991
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Earlier we proposed a modified version of the Anderson lattice model where the intersite coherence effects can be properly included even in the large limit of the spin-orbital degeneracy
N and investigated the low temperature Fermi liquid properties rigorously in the limit
N→∞. In the present study, using the same model as above, we investigate properties over the whole temperature range through explicit numerical calculations for
N=6. We find that a coherence temperature
T0 of order of one tenth of the Kondo temperature
TK exists; at lower temperature
T\lesssim
T0 the system is in the Fermi liquid state, while at higher temperature
T>>
T0 the electrons are scattered incoherently by the Kondo impurities. At intermediate temperature, with increasing
T, the hybridization gap appeared in the Fermi liquid state decreases rapidly at
T\gtrsim
T0, then smoothly turns into the pseudo gap at
T\simeq
TK, and finally the dense Kondo regime is realized at
T\gtrsim
TK.
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Hiroaki Yamada, Masaki Goda, Yoji Aizawa
1991 Volume 60 Issue 10 Pages
3501-3509
Published: October 15, 1991
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A universal probability distribution of resistance and transmission coefficient in a one dimensional disordered system proposed by Mello from a macroscopic point of view is examined numerically from a microscopic point of view for some tightly binding disordered systems. Some universal relations between the cumulants are well observed at the band center energy
E=0 in a weakly disordered system, while these are modified at the other energies
E≠0. They are modified even at
E=0 in the strongly disordered system. It is further found that the universal relations are broken in a modified Bernoulli system with an inverse-power law structural correlation.
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Hiroshi Nozaki, Hiroaki Wada, Shunji Takekawa
1991 Volume 60 Issue 10 Pages
3510-3515
Published: October 15, 1991
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The electrical resistivity, Hall effect, magnetoresistance and magnetic susceptibility of Ta
3S
2, Ta
2S and Ta
6S are reported for the first time. The Hall coefficient of Ta
3S
2 changes its sign from positive to negative with increasing temperature. The Hall coefficient is pronouncedly dependent on magnetic field strength below 77 K. The magnetoresistance increases almost quadratically with the field strength below 77 K, and is still observed at 291 K. These results are interpreted in terms of two bands with the carrier densitiy 3.0×10
19 cm
−3 of electrons and 7.9×10
17 cm
−3 of holes. These results strongly suggest that Ta
3S
2 is a semimetal with very slightly overlapping conduction and valence bands near the Fermi level. In contrast with Ta
3S
2, the compound Ta
2S is a metal with hole conduction, while Ta
6S is a metal with electron conduction.
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Kenji Ishida, Yoshio Kitaoka, Guo-qing Zheng, Kunisuke Asayama
1991 Volume 60 Issue 10 Pages
3516-3524
Published: October 15, 1991
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17O and
63Cu NMR measurements have been made in L
1.85Sr
0.15CuO
4 with
Tc=38 K. Both
17O Knight shift and quadrupole tensor were determined from the analyses of the
17O spectrum of oriented powder. The quadrupole frequencies of the planar oxygen and Cu nuclei are consistently interpreted by the analyses of Hanzawa
et al. made in YBa
2Cu
3O
7 with the electric field gradients due to the
on-site holes at Cu and O sites. Then the weight factor of the Cu-3
d(
x2−
y2) and 2
pσ wave functions are deduced, the latter having the larger weight. From the Knight shifts vs the bulk susceptibility plots, the hyperfine coupling constants for
17O and
63Cu were almost the same as those in YBa
2Cu
3O
7. Both shifts decrease significantly below
Tc having residual parts of
63Kab=0.38% and
17Kc=0.02% at 4.2 K, which were larger than those in YBa
2Cu
3O
7.
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Ichiro Hiromitsu, Hitoshi Aoyama, Jun Takeuchi, Takashi Ito
1991 Volume 60 Issue 10 Pages
3525-3536
Published: October 15, 1991
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Magnetism of iodine doped fluoro-aluminum phthalocyanine (AlPcF) film is studied by electron spin resonance (ESR) in two stable doping states: In State I, a doped AlPcF film is always in contact with saturated I
2 gas (AlPcF·I
4.0); In State II, a doped film is in no contact with I
2 gas (AlPcF·I
0.10). An antiferromagnetic transition is observed in both states. In State I in vacuum, the transition temperature depends on samples and the highest transition temperature observed is 160 K. In State II, it does not depend on samples and is 150 K in vacuum and 220 K at 1 atm. The occurrence of the magnetic transition indicates an existence of three dimensional magnetic coupling, i.e. interchain and intrachain couplings. An information about back charge transfer probability from I
3− to (
Remark: Graphics omitted.) in State II is obtained from a degree of
g anisotropy. With a help of this information, possible mechanisms of the interchain coupling are discussed.
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Salah A. Makhlouf, Masayuki Shiga, Kenji Sumiyama
1991 Volume 60 Issue 10 Pages
3537-3542
Published: October 15, 1991
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Mössbauer spectra of Fe
1−xAl
x alloys produced by facing target type DC sputtering have been measured for
x<0.75 at room temperature and 4.2 K . In the bcc alloys, hyperfine field distributions obtained by analyzing these spectra can be divided into three components characterized by three broad maxima. A nearest neighbor environment model, assuming random distribution of atoms, was successfully applied to explain the magnetic behavior of bcc alloys indicating that the sputtered FeAl alloys are in disordered state. The lattice constants of the bcc Fe–Al alloys were discussed in connection with the magnetic moment.
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Teruo Kôhashi, F. R. de Boer, R. J. Radwanski, X. P. Zhong, Akio ...
1991 Volume 60 Issue 10 Pages
3543-3548
Published: October 15, 1991
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A magnetization study in pulsed high magnetic fields up to 50 T has been performed on magnetically-aligned powder samples of ferrimagnetic Er
2Fe
14−xAl
xB (
x=0, 1, 2) compounds and field-induced transitions have been observed in high fields. Free-energy calculations with one Fe and four Er sublattices have been performed and the field-induced transitions can satisfactorily be explained. The Er- and Fe-sublattice moments, two kinds of anisotropy and molecular fields on Er ions have been determined.
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Chieko Totsuji, Takeo Matsubara
1991 Volume 60 Issue 10 Pages
3549-3556
Published: October 15, 1991
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The ferroelectric phase transition in some quantum-paraelectrics under the uniaxial stress is analyzed on the basis of the vibronically coupled two-band theory which takes into account the anharmonicity of lattice deformation. By calculating the electronic band structure and the density of states, it is shown that the uniaxial stress has an effect on the soft mode frequency similar to the one due to mixing in the case of mixtures of incipient ferroelectrics. Resultant critical stresses for the transition are consistent with available experimental data for KTaO
3 and SrTiO
3.
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Sadao Uemura, Kazi Monowar Abedin, Masashi Okada, Hiroki Nakatsuka
1991 Volume 60 Issue 10 Pages
3557-3567
Published: October 15, 1991
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We have derived a non-exponential stimulated photon echo decay function exp (−
cTτ
D⁄3) by assuming that the TLSs of the amorphous host are spatially distributed like a fractal with a fractal dimension
D, where
c is a constant,
T is the temperature and τ is the delay time between the first and second excitation pulses. From this function and the measured photon echo decay curves and hole shapes, we obtained
D=2.1∼2.3 for 1,3,3,1′,3′,3′-hexamethyl-2,2′-indotricarbocyanine iodide in polyvinyl alcohol (HITC/PVA), and
D=2.7 for HITC in ethanol (HITC/EtOH). These values of
D are consistent with the possible structures of the long chained polymeric glass and the monomeric glass, respectively. The photon echo decay function also gives a power law temperature dependence of the hole width
Γhole as
Γhole∝
T3⁄D. The deviation of the hole width in HITC/PVA from the power law temperature dependence at high temperatures is explained by a fracton mode of the amorphous host.
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Kazuhiro Hara, Haruichi Kanaya, Hirotaka Okabe, Kazumi Matsushige
1991 Volume 60 Issue 10 Pages
3568-3572
Published: October 15, 1991
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Time-resolved transmitted light spectra (λ=400∼800 nm) through gelling tungstic acid have been observed. As the gelation proceeds, intensity of the transmitted light decreases, remarkably in the short-wavelength region. It is found that ln τ (τ; turbidity) shows approximately linear dependence on ln λ, and that the slope varies as proceeding the gelation. These results can be explained by increase in the internal interference of the scattered lights from growing cluster.
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David A. Noever
1991 Volume 60 Issue 10 Pages
3573-3578
Published: October 15, 1991
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Biologically generated cellular patterns, sometimes called bioconvective patterns, are found to cluster into aggregates which follow fractal growth dynamics akin to diffusion-limited aggregation (DLA) models. The pattern formed is self-similar with fractal dimension of 1.66±0.038. Bioconvective DLA branching results from thermal roughening which shifts the balance between ordering viscous forces and disordering cell motility and random diffusion. The phase diagram for pattern morphology includes DLA, boundary spokes, random clusters and reverse clusters.
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Koichi Shindo, Atsushi Nishikawa
1991 Volume 60 Issue 10 Pages
3579-3580
Published: October 15, 1991
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Takayuki Goto, Tetsuo Nomoto, Tetsuo Hanaguri, Takeshi Shinohara, Taka ...
1991 Volume 60 Issue 10 Pages
3581-3582
Published: October 15, 1991
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V. Rajeswari, K. Srinivasa Rao
1991 Volume 60 Issue 10 Pages
3583-3584
Published: October 15, 1991
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