-
Iwao Hosokawa
1991 Volume 60 Issue 12 Pages
3983-3985
Published: December 15, 1991
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It is shown that a self-similar measure isotropically distributed in a
d-dimensional set should have its own intermittency exponents equivalent to its own generalized dimensions (in the sense of Hentschel and Procaccia), and that the intermittency exponents are completely designated by an intrinsic probability which governs the spatial distribution of the measure. Based on this, it is proven that the intrinsic probability uniquely determines the spatial distribution of the scaling index α of the measure as well as the so-called
f-α spectrum of the multifractal set.
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Kenji Kajiwara, Junkichi Satsuma
1991 Volume 60 Issue 12 Pages
3986-3989
Published: December 15, 1991
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A
q-difference version of the two-dimensional Toda lattice equation is proposed. Through a suitable reduction, it reduces to the
q-difference version of the cylindrical Toda lattice equation. It is shown that the reduced equation admits solutions expressed by the
q-Bessel function.
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Masuo Suzuki, Naomichi Hatano, Yoshihiko Nonomura
1991 Volume 60 Issue 12 Pages
3990-3992
Published: December 15, 1991
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It is shown phenomenologically that the double-cluster approximation is canonical in the sense of the CAM theory, namely that the coherent anomaly appearing in a series of double-cluster approximations gives asymptotically correct values of critical exponents without any logarithmic correction. This is a basic property desired in the CAM.
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Yoshiyuki Kabashima, Shigeru Shinomoto
1991 Volume 60 Issue 12 Pages
3993-3996
Published: December 15, 1991
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In order to find a low-energy state through annealing, one generally must immerse a system in a heat bath for a long time. Asymptotic dependence of the resultant energy ε on time τ spent in annealing is a matter of current interest. By comparing the established scaling forms of ε(τ) for three kinds of systems, we propose that the functional form of ‘density of local minima’
D(
E) is a key to the determination of scaling ε(τ). For instance, ε∝1⁄ln τ if
D(
E)∝
Eα. Numerical simulation of one-dimensional white-noise potential models is carried out to examine the conjecture. The result is consistent with the conjecture.
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Takashi Nagatani
1991 Volume 60 Issue 12 Pages
3997-4000
Published: December 15, 1991
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A growth model is presented to simulate pit formation in pitting corrosion in three dimensions. The pit growth model is described in terms of the anti-diffusion-limited aggregation (anti-DLA) model. Computer simulation is performed to study the scaling structure of a single pit in pitting corrosion. It is found that the bird’s-eye view of the corrosion pit profile shows a compact structure having a fractal surface. The fractal dimension
D of the surface of the bird’s-eye profile of the corrosion pit is given by
D=1.168. It is also found that the width and depth of the corrosion pit show a scaling form. The width w and depth h of the pit scale as
w≈
n0.39±0.04 and
h≈
n0.28±0.04 where
n is the particle number removed from metal. The width
w against depth
h scales as
w≈
h1.39±0.05.
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Kikuo Harigaya
1991 Volume 60 Issue 12 Pages
4001-4004
Published: December 15, 1991
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Lattice and electronic structures of undoped and doped C
60 are investigated. The Su-Schrieffer-Heeger model is extended and solved numerically. For the undoped system, electronic level structures agree well with those of th tight-binding model [Hayden and Mele: Phys. Rev. B
36 (1987) 5010]. When one or two electrons are added or removed, the lattice deforms and two levels intrude into the energy gap like a polaron in polyacetylene. The dimerization becomes weaker along a meridian. Consequences of “polarons” for experimental studies are discussed.
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Yuji Saitoh, Shigemasa Suga, Hideki Matsubara, Yasuhiko Tsukikawa, Yas ...
1991 Volume 60 Issue 12 Pages
4005-4008
Published: December 15, 1991
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X-ray bremsstrahlung isochromat spectra (BIS) as well as photoemission spectra (XPS) are measured for YbP, YbAs and Yb
4As
3. The BIS spectra have revealed clear differences in the Yb 4f and 5d states between the Yb-monopnictides and Yb
4As
3. Yb 4p and 5p core XPS spectra have shown the mixed valence of Yb
4As
3 compared with the predominance of Yb
3+ in Yb-monopnictides.
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Katsuhiko Takegahara, Yasunori Kaneta
1991 Volume 60 Issue 12 Pages
4009-4012
Published: December 15, 1991
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The one-electron energy band structure for YbAs and Yb
4As
3 is calculated up to 1.5 Ry above the Fermi energy by a self-consistent augmented plane wave (APW) method with the local density approximation. The calculated unoccupied density of states is compared with the observed bremsstrahlung isochromat spectroscopy (BIS) spectra. In YbAs, two peaks appear at about 5.5 and 10 eV above the Fermi energy, in good agreement with the experimental result. These originate from the Yb 5
d and the Yb 5
d-As 4
p antibonding states, respectively. In Yb
4As
3, a broad peak originating from the Yb 5
d states combined with the antibonding state appears at about 5.5 eV above the Fermi energy. The discrepancy between calculated and observed peak positions is due to the valence fluctuation.
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Yoshimasa Isawa, Masakazu Kanechika
1991 Volume 60 Issue 12 Pages
4013-4016
Published: December 15, 1991
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Electron tunneling through a double barrier separated by a quantum well is studied. We find that the tunneling current is described as the sum of the contributions of two distinct processes. One is due to the coherent tunneling, and the other is a sequential one in which the phase coherence of the electron wave is destroyed between two tunneling steps. With increasing strength of scattering in the quantum well, the dominant tunneling process changes from the coherent one to the sequential one. We also find that the sequential tunneling is not a single incoherent tunnel process, but consists of three processes in which a new interference process plays an important role.
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Satoshi Okuma, Hajime Koyanagi, Nobuhiko Nishida
1991 Volume 60 Issue 12 Pages
4017-4021
Published: December 15, 1991
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In thin granular films composed of two-dimensionally coupled indium particles, we have studied how the superconductivity will be influenced by the average particle size. The coupling strength has been changed continuously with an average diameter \bar
d of particles as constant as possible in a film. For films with \bar
d=280 A and 224 A, superconducting transition temperature decreases very slowly with increasing sheet resistance
Rn in the normal state, while for a film with \bar
d=140 A it decreases linearly with
Rn, indicating that the system changes to a dirty superconductor by reducing \bar
d. Critical resistance for the onset of superconductivity will be discussed.
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Fumitaka Matsubara, Taketoshi Iyota, Sakari Inawashiro
1991 Volume 60 Issue 12 Pages
4022-4025
Published: December 15, 1991
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The short-range ±
J Heisenberg model with the concentration of ferromagnetic bonds
p on a simple cubic lattice is studied using a hybrid Monte-Carlo spin-dynamics (HMCSD) method. Using a finite-size scaling analysis, we find the critical concentration of
pc=0.79±0.01 and the ferromagnetic phase transition for
p>
pc which belongs to the same universality class as that of the pure ferromagnet. We also find that no random spin freezing occurs in our model.
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Satoshi Takada, Kenn Kubo
1991 Volume 60 Issue 12 Pages
4026-4028
Published: December 15, 1991
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We propose
nonlocal unitary transformations on
S=1 antiferromagnetic chains in a simple operator form. This is a generalization of the transformation recently introduced by Kennedy and Tasaki to clarify the hidden symmetry in the Haldane phase. The three operators (
Tlα≡
iSlα e
lπSlβ) appearing in these transformations are examined and some simple algebraic relations are shown to hold among
Tlα and
Slα. It is also shown that three different forms of transformed Hamiltonians are transformed into each other by
local unitary transformations.
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Hirokazu Nakayama, Taro Eguchi
1991 Volume 60 Issue 12 Pages
4029-4031
Published: December 15, 1991
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A curious phase transition in the crystals of 4,4′-dichlorobenzophenone has been found to occur at 331±2 K by DTA and
35Cl NQR measurements. A single NQR line observed at room temperature splits into two lines above 331 K. The frequency difference between these two lines (
Δν) becomes large as temperature increases and the relation
Δν∝(
T−320) holds in the temperature region up to the melting point (418 K). A quasi-continuous nature of the transition reflects on this behavior of
Δν. The symmetry in the high-temperature phase is lower than that in the room-temperature phase. It is probable that the transition accompanies the symmetry lowering of the molecular structure in the high-temperature phase of the crystal.
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Nobumori Kinoshita, Yasumoto Tanaka, Madoka Tokumoto, Shigeki Matsumiy ...
1991 Volume 60 Issue 12 Pages
4032-4035
Published: December 15, 1991
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Electron spin resonance (ESR) study of halogen-doped C
60 was carried out by varying the doping conditions such as concentration and annealing time. Temperature dependence of the ESR linewidth of C
60Br
x different from that of K
xC
60 was obtained. The electronic properties of C
60Br
x and K
xC
60 were discussed.
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Taizo Masumi, Hidetoshi Minami, Hiroshi Shimada
1991 Volume 60 Issue 12 Pages
4036-4039
Published: December 15, 1991
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A series of systematic studies of the novel spectral photoconductivity of the Y
3−x–Ba
x–Cu
3–O
z system conjugate with high-
Tc superconductivity have been performed. On the basis of the experimental results, we propose that a photoexcited state of the insulators is equivalent to the ground state of the high-
Tc superconductors in the Y
3−x–Ba
x–Cu
3–O
z system.
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Hidetoshi Minami, Taizo Masumi
1991 Volume 60 Issue 12 Pages
4040-4043
Published: December 15, 1991
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Single crystals of bismuth oxide with rhombohedral layered structure have been synthesized for the first time by means of stabilization with addition of the divalent metals Sr, Ca and Cu. Novel temperature dependence of transient photoconductivity clearly indicates anomalously sustained life time of photocarriers together with magneto-resistance mobility and suggests the relaxation process due to the exciton formation with large binding energy. Similar temperature dependences have been observed also in the host insulators of high-
Tc superconductors.
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Isamu Nakata
1991 Volume 60 Issue 12 Pages
4045-4050
Published: December 15, 1991
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Weak nonlinear waves on an
LC ladder line with small random imhomogeneities are investigated. By means of a nonlinear perturbation method, a nonlinear integro-differential equation which describes asymptotic behaviour of weak nonlinear waves on the line is derived from the basic system of equations. It is shown from this equation that the amplitude of a solitary wave decays due to the presence of the random inhomogeneities. The possibility of shock wave propagation due to the presence of the random inhomogeneities is also shown.
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Tetsuo Deguchi, Yasuhiro Akutsu
1991 Volume 60 Issue 12 Pages
4051-4059
Published: December 15, 1991
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We present a new hierarchy of solutions of the colored Yang-Baxter relation. They are generalizations of colored braid matrices with
ZN graded symmetry. We explicitly give the Boltzmann weights of the
N-state colored vertex models for
N=2, 3, and 4. We also discuss the Boltzmann weights for
N>4.
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Masao Nomura
1991 Volume 60 Issue 12 Pages
4060-4070
Published: December 15, 1991
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Quantum matrix algebras
suq(2) are realized in terms of single-state boson operators and their conjugates, (
a+,
a), (
b+,
b), etc., specified as quantum analogs of symplectons. The boson operators obey the linear transformation of
SUq(2) such as
a′
+=
a+x+
av and
a′=
a+u+
ay. Here,
x,
u,
v,
y are non-commutative elements which commute with
a+ and
a. Commutation relations for creation and annihilation operators are determined so as to be invariant under the linear transformation. Exchange algebras with the universal
Rj′j″ matrix are realized in terms of
P(
j′,
m′;
b),
P(
j″,
m″;
a), etc., where
P(
j′,
m′;
b) is the
jz′=
m′ component of rank-
j′ tensor written as an order-2
j′ polynomial in
b+ and
b.
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Jorge Fujioka, Aurea Espinosa
1991 Volume 60 Issue 12 Pages
4071-4075
Published: December 15, 1991
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The direct method of Clarkson and Kruskal is used to obtain the similarity reductions of a simplified version of the Hirota-Satsuma equation. It is also shown that no similarity reductions can be found by the classical Lie’s method, as there are no infinitesimal transformations that leave invariant the integrodifferential equation under study.
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Michisuke Kobayashi, Fuyuki Shimojo
1991 Volume 60 Issue 12 Pages
4076-4080
Published: December 15, 1991
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The fractal behavior of diffusion trajectories of ions is studied in the α and molten phases of AgI using molecular dynamics simulations. At the temperature just over the melting temperature, the fractional fractal dimension
D=2.17 for I ions and
D=2 for Ag ions are gotten in reflection with the fore-running phenomenon to the crystalization of I ions. At an extremely high temperature over the melting temperature, the system is in completely liquid state, which leads to a value of
D=2 for Ag and I ions.
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Keiji Kosaka, Katsumi Yonei
1991 Volume 60 Issue 12 Pages
4081-4088
Published: December 15, 1991
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The validity of the relativistic WKB method proposed in a previous paper [J. Phys. Soc. Jpn.
60 (1991) 850] is examined for bound states of an electron in screened Coulomb potential. To this end the radial Dirac equation is solved both exactly and approximately for a model potential of a simple analytic form and the results are compared. Through a detailed comparison, it is shown that the relativistic WKB method gives energies and wavefunctions which are in good agreement with the exact. Several features in the relativistic WKB wavefunctions are also pointed out.
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Kaoru Ohya, Ichiro Mori
1991 Volume 60 Issue 12 Pages
4089-4099
Published: December 15, 1991
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An investigation is made of the elastic scattering of protons in solids in the low-energy range by use of the method of partial waves with the atomic potential of solid atoms being calculated using the muffin-tin approximation. The resulting differential cross-sections never diverge near zero scattering angles showing weak forward scattering and oscillating behavior at small scattering angles. The mean free path is approximately independent of energy and is close to the average atomic distance. In addition, a Monte Carlo simulation of the transport of protons in C, Al, and Cu is carried out by using the present cross-section (potential). The result shows only small changes in the trajectory and back-scattering yield from those obtained by using the well-known Ziegler-Biersack-Littmark potential, in spite of large differences between the scattering properties of the two potentials.
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Isao Imai
1991 Volume 60 Issue 12 Pages
4100-4118
Published: December 15, 1991
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A new framework of electromagnetic theory is presented on the basis of conservation principles of energy and momentum. First, Maxwell’s equations and Lorentz force law in vacuum are derived as theorems from the conservation principles. Next, new kinds of averaging procedure, transversal and longitudinal, are introduced to deal with the macroscopic media. Electromagnetic field (
E,
H) and flux density (
D,
B) are defined as the longitudinal and transversal averages of the corresponding microscopic field. The polarization
P and magnetization
M defined as
P=
D−ε
0E,
M=
B−μ
0H are given explicit expressions in terms of microscopic electromagnetic structure of the matter. Lorentz transformation of space-time and electromagnetic field can be derived entirely within the framework of electromagnetic theory.
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Akira Yoshizawa
1991 Volume 60 Issue 12 Pages
4119-4126
Published: December 15, 1991
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A mass-weighted mean compressible turbulence model is presented with the aid of the results from a two-scale DIA. This model aims at dealing with two typical aspects in compressible flows: the interaction of a shock wave with turbulence in high-speed flows and strong buoyancy effects in thermally-driven flows as in stellar convection and conflagration. The former is taken into account through the effect of turbulent dilatation that is related to the density fluctuation and leads to the enhanced kinetic energy dissipation. The latter is incorporated through the interaction between the gravitational and density-fluctuation effects.
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Hiroaki Ono
1991 Volume 60 Issue 12 Pages
4127-4132
Published: December 15, 1991
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Using the reductive perturbation method, the modulation of gravity waves propagating over uneven bottom is investigated. It is shown that such a process can be described by the nonlinear Schrödinger equation with an additional pure imaginary potential. For the case when the depth variation is weak, we have derived another equation, which can be formally transformed into the classical nonlinear Schrödinger equation. Based upon this equation, it is found that various types of envelope solitons and a phase jump solution may diffuse owing to stochastic variation of the depth.
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Shigehiko Nonaka
1991 Volume 60 Issue 12 Pages
4133-4145
Published: December 15, 1991
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The most fundamental solutions for effects of static magnetic field on radio frequency (RF) discharges between a pair of electrodes were obtained explicitly by solving a quasi-static linear Laplace equation. The magnetic field was assumed to be applied in parallel with the electrode plane. In this theory, the produced plasma density, threshold conditions for variable parameters and the phase and amplitude for electric field to maintain the discharges were formulated uniquely. These solutions were used to extract qualitative properties on the planar Electron Cyclotron Resonance (ECR) discharges.
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Noriyoshi Nakajima, Masao Okamoto
1991 Volume 60 Issue 12 Pages
4146-4153
Published: December 15, 1991
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Neoclassical rotations are investigated theoretically for a plasma consisting of electrons, bulk ions, and impurities in non-axisymmetric toroidal systems. Impurity ions are assumed to lie in the Pfirsch-Schluter collisionality regime. The results include the case of tokamaks. It is found that the rotations of impurities are genarally different from those of bulk ions. The difference comes from mainly the different diamagnetic flows between bulk ions and impurities. In the 1⁄ν regime or banana regime the gradient of bulk ion temperature may be another cause for the different rotations between the two species. However, in the region where the configuration is far from the axisymmetry the cause of different rotations is just the different diamagnetic flows. As the poloidal rotations depend on the radial electric field contrary to the axisymmetric system, a relationship, which does not include the radial electric field, can be derived between poloidal and toroidal rotations. By estimating this relationship based on the measured rotations the present neoclassical theory can be validated without knowledge of radial electric field.
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Takeshi Moriya, Yasuo Murata, Shinichi Murase, Osamu Yoshimura
1991 Volume 60 Issue 12 Pages
4154-4159
Published: December 15, 1991
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Low temperature anomalies in the flow stress were found for the super saturated alloys of Cu-5 at.%Ti below about 40 K. Similar anomalies were also found for the specimens decomposed spinodally. These are consistent with our previous model. The shoulders at higher temperatures on the stress-temperature curves were interpreted as corresponding to the onset of short ranged unzippings generally accompanied by the transition from over to under damping mode of dislocation oscillations.
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Yukio Morii, Akira Nagasawa, Yoshie Matsuo, Satoru Funahashi, Harry R. ...
1991 Volume 60 Issue 12 Pages
4160-4166
Published: December 15, 1991
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Phase transition of β
1-AgZn alloy was studied by means of neutron inelastic and diffuse scattering techniques. Acoustic phonon dispersion relation along the main crystal axes of the alloy was obtained. No [ζζζ]LA phonon anomalies related to the ζ-phase was observed, although previous sound experiment followed by elastic constant analysis predicts that possibility. The observed anomalies in phonon energy of both [ζζ0]TA
1 and [ζζ−2ζ]TA modes associated with the diffuse scattering peaks indicate that a strong lattice instability is involved in the phonon modes. It is pointed out that the lattice instability plays important roles in the structure transition from β
1-phase to ζ-phase or to the martensitic phase in the AgZn alloy.
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Takeshi Iizuka, Takenobu Nakao, Miki Wadati
1991 Volume 60 Issue 12 Pages
4167-4174
Published: December 15, 1991
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Wave propagations in nonlinear lattices with random mass distribution are investigated. The following two cases which have important applications are studied; 1) slowly varying waves in a lattice with a cubic nonlinearity, and 2) carrier wave modulations in a lattice with quadratic and cubic nonlinearities. The former and the latter cases reduces to stochastic modified Korteweg-de Vries equation and stochastic nonlinear Schrödinger equation, respectively. Propagations of solitons are analysed for both cases under an assumption that mass distribution is Gaussian and white.
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Hongye Sun, Hiroshi Orihara, Yoshihiro Ishibashi
1991 Volume 60 Issue 12 Pages
4175-4180
Published: December 15, 1991
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The temperature dependence of phase mode relaxation frequencies in the SmC
A* phase (antiferroelectric phase), SmC
γ* phase (ferrielecric phase) and SmC
* phase (ferroelectric phase), and the dispersion of the phase mode in the SmC
γ* phase were measured by photon correlation technique in R–MHPOBC (
Remark: Graphics omitted.). The relaxation frequencies of the phase modes in SmC
A* and SmC
* are almost the same and are much higher than that in the SmC
γ* phase. The relaxation frequency gradually decreases with decreasing temperature in the SmC
A* phase. In the SmC
γ* phase, the phase mode shows a parabolic dispersion.
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Sizuka Kurioka, Kazuyosi Ikeda
1991 Volume 60 Issue 12 Pages
4181-4198
Published: December 15, 1991
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The thermodynamical behaviour of liquid water, especially the anomalous behaviour (negative thermal expansivity etc.) near the triple point, is rigorously investigated on the basis of both the theoretical framework established in the authors′ previous paper (by using the model of one-dimensional gas) and the experimental data accumulated for water. Thermodynamical diagrams in the
T-
V,
P-
T and
P-
V planes (
T=temperature,
V=volume,
P=pressure) are drawn. The region
R (in the
T-
V plane), in which the pressure coefficient is negative, and the corresponding region
R′ (in the
P-
T plane), in which the thermal expansivity is negative, are studied, especially in relation to the intersection and inversion of isotherms in the
P-
V plane. The anomalous behaviour of
P-
V isotherms for liquid water (including their intersection with each other, their touching the maximum-density curve, and their crossing the freezing and boiling curves) is discussed.
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Katsuhiko Hasebe, Takanao Asahi
1991 Volume 60 Issue 12 Pages
4199-4202
Published: December 15, 1991
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On the basis of the reported result that the SO
4 ion behaves as an order-disorder unit, the phase transition of LiCsSO
4 is discussed by the order parameter-shear strain
x6 coupled model. Constants appeared in the model free energy are estimated: The value of the fourth order coefficient of order parameter is extremely small. Temperature variation of the spontaneous strains
x1s,
x2s,
x3s and
x6s, intensities of Bragg reflections, and the elastic constant
c66 are explained by the present model.
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Tadao Ishii
1991 Volume 60 Issue 12 Pages
4203-4212
Published: December 15, 1991
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Dynamical properties due to hopping of an excited kink on the ground state kink-lattice are studied in the Frenkel-Kontorova model in one-dimensional ionic conductors, by an evaluation of the correlation function of kink field density which directly concerns the NMR-
T1 for the quadrupole coupling. The hopping is treated by the relaxation mode theory. The resultant relaxation time
T1 approaches to the ω
1.5-dependence when the diffusion length becomes less than the correlation length. The slope energy of ln
T1, in this case, is determined by the sum of the renormalized kink energy and half of the kink-activation energy, which is quite consistent with the observed value from the NMR-
T1 experiment in the K–Al-priderite.
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J. L. Reno, E. D. Jones
1991 Volume 60 Issue 12 Pages
4213-4217
Published: December 15, 1991
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We have grown strained Cd
1−xZn
xTe/CdTe single strained quantum wells by molecular beam epitaxy. The Zn concentration was varied from 10 to 60% and the well widths were systematically increased until the critical thickness was exceeded. Low-temperature (liquid helium) photoluminescence spectroscopy was used to characterize the films. The energy of the quantum well luminescence is consistent with a simple square well model when strain is included. The critical layer thickness for the CdTe quantum wells was found to be in agreement with the model of Matthews and Blakeslee.
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Noriyuki Takano, Satoshi Imai, Mitsuru Fukuchi
1991 Volume 60 Issue 12 Pages
4218-4221
Published: December 15, 1991
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Short-range order (SRO) is introduced into the electronic structure calculation with the KKR-cluster CPA using the probability densities of Markovian pair type. This formalism is applied to Cu
0.5Pd
0.5. When the probability of SRO is higher, the density of states in the middle of the energy bands are enhanced. It is predicted that the band structure energy decreases if the probability of SRO increases.
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Seiichi Kagoshima, Noriaki Sugimoto, Toshihito Osada, Akiko Kobayashi, ...
1991 Volume 60 Issue 12 Pages
4222-4229
Published: December 15, 1991
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Temperature dependence of magnetic susceptibilities and lattice parameters is measured at ambient pressure in the title compounds, which are metallic down to the lowest temperature measured and have a mixed valence state of Cu. In (DMeDCNQI)
2Cu an anomalously large susceptibility having a thermal hysteresis is found in the range below 100 K. This result combined with the change in the lattice parameter tells that (DMeDCNQI)
2Cu is a marginal metal in which the number of stable Cu
2+ ions changes with temperature. It is pointed out that the reentrant behavior already found in the title compounds under respective pressure range has a close relation with the lattice-parameter change.
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Masanori Matoba, Shuichiro Anzai, Atsushi Fujimori
1991 Volume 60 Issue 12 Pages
4230-4244
Published: December 15, 1991
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Magnetic susceptibility χ, electrical resistivity ρ, thermoelectric power
S, XPS spectra and hexagonal lattice parameters
c and
a are measured on the NiAs-type Ni
1−xS
1−ySe
y (
x≤0.04;
y≤1.00). We find the followings (1) the nonmetal-metal transition temperature
Tt, the phonon-drag coefficient
C below
Tt and dχ(
T>
Tt)⁄d
T decrease and they are suppressed at
xc and
yc with increase in
x and
y, respectively. (2) The nearest neighboring S
1−ySe
y(Z)–Z, Ni–Z and Ni–Ni distances just below
Tt (
DZ–ZN,
DNi–ZN,
DNi–NiN, respectively) are depressed with increase in
x.
DZ–ZN and
DNi–NiN only slightly depend on
y, while
DNi–ZN increases with increasing
y. (3) No change in the
d8L peak (
L: hole in the Z network) in the valence band region is observed among Ni
1−xS
1−ySe
y and Ni
0.93Te. (4) The Ni
2p3⁄2d9L core level peak shifts to lower binding energy
EB with increasing
y, while it hardly changes with
x. (5) The
EB of S 2
s and S 2
p core levels decrease with increasing
x; the
EB of S 2
p one decreases with increasing
y. From the view point of the charge-transfer model, the pressure and the Ni-vacancy substitution effects on
Tt are mainly explained by the increase in the Z(
p) band width, and the Se-substitution effect by the decrease in the charge-transfer energy. The Ni-vacancies also introduce extra holes in the Z(
p) band.
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Tatsumi Kurosawa
1991 Volume 60 Issue 12 Pages
4245-4252
Published: December 15, 1991
Released on J-STAGE: June 01, 2007
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The effects of band warping on the streaming motion of carriers, particularly on the bunching behaviour in momentum space, under crossed intense microwave and static magnetic fields, are examined. Numerical analyses are carried out for heavy holes in germanium, for which the experimental evidences on the carrier bunching have been obtained, in two representative arrangements of the filds. The general features of the results are similar to each other and to those in the spherical band case. The bunching behaviour with rapid convergence is found in the intermediate magnetic field range.
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Chu-Nan Chang, Syh-Bin Lee, Chuhn-Chih Chen
1991 Volume 60 Issue 12 Pages
4253-4264
Published: December 15, 1991
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The isotropic Compton profiles of Ag for two thicknesses, 2 mm and 4 mm, have been measured by means of 662 keV γ-rays from Cs
137 source. A HpGe detector with resolution of 190 eV at 5.9 keV was used to detect the backward scattering photons. Comparison with the renormalized-free-atom model calculations was made, and the agreement between the experimental and the calculated values has been found to be good for the electron configuration 4d
105s
1.
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Yoshimasa Murayama, Sadao Nakajima
1991 Volume 60 Issue 12 Pages
4265-4279
Published: December 15, 1991
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By applying the holon-doublon formalism to a highly correlated system consisting of
d- and
p-electrons, a theory is developed concerning whether a superconductive phase can be realized in parallel to the previously investigated single-band model. The result follows: those
d-states hybridized with (partially occupied)
pσ+-band form pairs and are condensed into superconductive ground state. On this model almost all features characteristic to hole-doped, layer-structured high
Tc superconductors are, at least qualitatively, interpreted.
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Yasuaki Oohara, Katsunori Iio, Hidekazu Tanaka, Kazukiyo Nagata
1991 Volume 60 Issue 12 Pages
4280-4285
Published: December 15, 1991
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Short-range spin ordering of RbNiCl
3 in the critical region of the magnetic phase transition is observed by the birefringence technique. The temperature derivative of the
ac-plane birefringence, corresponding to specific heat, shows an almost divergent anomaly at 11.3 K, which is resulted from coalescing two singularities at the successive phase transitions inherent to an Ising-like Heisenberg triangular lattice antiferromagnet. The critical exponent \ ildeβ is determined as 0.76±0.03 from the data on the temperature dependence of the symmetry-breaking birefringence
Δnxy. The almost divergent anomaly of specific heat and the value of \ ildeβ mean that the criticality does not belong to the 3d-
XY universality class, in which a cusp-like anomaly in specific heat and \ ildeβ of 0.85, are theoretically predicted for both of the successive phase transitions of Ising-like Heisenberg triangular lattice antiferromagnets. This can be explained by the crossover effect from the universality class of 3d-SO(3) or 3d-S
1×S
1 to the 3d-
XY, as concluded in a recent neutron scattering study.
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Tsuneaki Goto, Kazushi Kuroda, Kazuaki Fukamichi, Hiroyuki Komatsu, Se ...
1991 Volume 60 Issue 12 Pages
4286-4299
Published: December 15, 1991
Released on J-STAGE: May 29, 2007
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A magnetic phase diagram of amorphous Fe
100−XLu
X was determined from AC susceptibility and remanent magnetization measurements. The alloys with 30≤
X≤40 exhibit a spin glass behavior. The alloys with 10.5≤
X≤25 are ferromagnetic, but show a reentrant spin glass behavior at low temperatures. The reentrant spin glass phase is divided into two phases with weak and strong irreversibility. The ferromagnetic state becomes unstable as
X approaches to 8. For
X=8, the ferromagnetic state disappears and a direct transition from the paramagnetic to spin glass state is observed. The high field magnetization measurements imply that the instability of ferromagnetism and the appearance of the spin glass state are caused by the development of antiferromagnetic interactions. In the reentrant spin glass state, the freezing of transverse components of spins is confirmed by the analysis of the Mössbauer spectra.
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Shinpei Fujii, Shoji Ishida, Setsuro Asano
1991 Volume 60 Issue 12 Pages
4300-4310
Published: December 15, 1991
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We perfomed total-energy band calculations for Mn, FeMn, Fe
3Mn and Fe in gamma phase. In the calculations, we dealt with not only a collinear spin arrangement but also non-collinear spin arrangements in the local density approximation. Apart from gamma-Fe and FeMn, we obtained reasonable results in the ground-state spin arrangement and magnetic moments.
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Shintaro Nakamura, Terutaka Goto, Mitsuo Kasaya, Satoru Kunii
1991 Volume 60 Issue 12 Pages
4311-4318
Published: December 15, 1991
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Temperature dependence of the elastic constants in the valence fluctuation compound of SmB
6 and the reference one of LaB
6 has been investigated by an ultrasonic method. The DC sputtering technique of a piezoelectric ZnO film on SmB
6 has been employed for a reliable ultrasonic measurement free from bond breaks. A remarkable softening of the bulk modulus
CB and an anomaly of the
C44 mode in SmB
6 are responsible for the interaction between the elastic strain and the narrow 4f-band state with the energy gap of 160 K around the Fermi level.
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Masanori Arakawa, Toshikazu Hirose, Hideo Takeuchi
1991 Volume 60 Issue 12 Pages
4319-4325
Published: December 15, 1991
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EPR measurements have been made on a Fe
3+ centre in single crystals of Bi
2WO
6 at room temperature using X-band spectrometer. The fine structure interaction is much stronger than the Zeeman interaction and the principal ζ-axis of the second-rank fine structure tcnsor is close to the direction of the crystalline layer axis (
b-axis). It is found from superposition-model analyses of the fine-structure parameters that the Fe
3+ ion substitutes for a Bi
3+ ion. The large magnitudes of the parameters
b20=1.40(1),
b21=−0.36(1),
b22=−0.09(1),
b2−1=0.34(1) and
b2−2=0.23(1) cm
−1 obtained in the (
cab)-coordinate system are explained by a deviation of Fe
3+ ion mainly along the
b-axis, so the piramidal structure of the centre in Bi
2O
2 layer is flattened from that of host crystal.
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Akikatsu Sawada, Keisuke Tanaka
1991 Volume 60 Issue 12 Pages
4326-4330
Published: December 15, 1991
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The orthorhombic-monoclinic phase transition in [N(CH
3)
4]
2CoBr
4 crystals has been studied by measuring static dielectric constants along the
a,
b and
c axes in the wide range of temperature from 370 K down to 10 K including the transition temperature
Tc=287.0 K. Anomalous parts of dielectric constants due to the phase transition are found to show a broad maximum around 70 K for
b plate samples, while a shallow minimum around 120 K for
c plate samples. The phase transition in [N(CH
3)
4]
2CoBr
4 is regarded as the ferridistortive phase transition in which the spontaneous shear strain consists of two kinds of sublattice strains with opposite signs and different magnitudes.
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Tomoyuki Nagaya, Yoshihiro Ishibashi
1991 Volume 60 Issue 12 Pages
4331-4336
Published: December 15, 1991
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The ferroelectric switching process has been studied on the basis of a one-dimensional discrete lattice model. The characteristics of the model is discussed in the relationship with the Kolmogorov-Avrami(KA) model. It has turned out that the features in the early stage of the polarization reversal in the present model coincides with what described by the KA model.
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Masayuki Sato, Keigo Nagasaka, Masaru Ihara, Takafumi Kimura
1991 Volume 60 Issue 12 Pages
4337-4350
Published: December 15, 1991
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Far-infrared transmission measurements of Bi–Sr–Ca–Cu–O superconducting thin films deposited on MgO substrates have been made in the range from 50 to 300 cm
−1 at temperatures between 7 and 174 K. Transmittance spectra cannot be explained by the Leplae theory of a conventional superconductor in the superconducting state, while transmittance spectra were fully explained by the Drude theory in the normal state. The discrepancy of a theoretical spectrum with the experimental spectrum is ascribed to a large portion of the real part of the optical conductivity below the so-called energy gap ∼400 cm
−1. Because these extra optical conductivities are proportional to their DC conductivities in many specimens, this extra optical conductivity is ascribed to an electronic excitation due to a low-lying energy gap and/or residual normal conductivity below 400 cm
−1.
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