-
Chihiro Matsuoka, Kazuhiro Nozaki
1992 Volume 61 Issue 5 Pages
1429-1432
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Equations of motion of vortices of the complex Ginzburg-Landau equation are derived using matched asymptotic expansions. It is shown that two vortices are repulsive and attractive for equal and opposite charges, respectively.
View full abstract
-
Shozo Takeno
1992 Volume 61 Issue 5 Pages
1433-1436
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Several lattice models of nonlinear excitation transfer in a
d-dimensional version of the simple cubic lattice are prcsented to show the existence of exact moving
d-dimensional nonlinear localized mode solutions. The eigenfrequencies of the localized modes appear either below or above the linear exciton frequency band. Profile functions of the four types of localized modes considered here are described by the sech-function, the square of the sech-function, the cosech-function and the square of the cosech-function, of which the first and the third are identified as envelope solitons in the
d-dimensional lattice.
View full abstract
-
Takashi Nagatani
1992 Volume 61 Issue 5 Pages
1437-1440
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
An unsteady effect of the diffusion on diffusion-limited aggregation (DLA) is studied using the multiparticle DLA model on the deposition plate in two dimensions (strip geometry). The multiparticle model can take into account the propagation of diffusing particles from the upper boundary toward the deposition plate. The initial value problem of the unsteady diffusion equation is simulated by the multiparticle DLA model. The morphological evolution is investigated by means of computer simulations. With increasing concentration, the morphology of the deposit becomes different from that grown in a steady state. In the dilute limit, the structure of the deposit agrees with that of the steady state.
View full abstract
-
Hirohito Kiwata, Yasuhiro Akutsu
1992 Volume 61 Issue 5 Pages
1441-1444
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We present an exactly solvable quantum SU(
M) (
M: arbitrary integer ≥2) spin chain with long-range (∼inverse-square) interactions. The model generalizes the so-called Haldane-Shastry system which corresponds to
M=2. We find the Lax pair for the system which guarantees the integrability of the system. An exact many-body ground-state wave function with particular symmetry is explicitly constructed.
View full abstract
-
Sadao Isogami, Mitsugu Matsushita
1992 Volume 61 Issue 5 Pages
1445-1448
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We study structural and statistical properties of a self-avoiding version of fractional Brownian motion (fBm) trajectories in two dimensions. The self-similarity of fBm trajectories is confirmed and their fractal dimensions
D are obtained. Closed loops of the fBm trajectories (self-avoiding fBm) are generated, and the relationship between their fractal dimensions
DSA and the Hurst exponent
H characterizing fBm curves is obtained. It is found that the size distribution of the loops of fBm obeys a power law with the exponent
f. The dependence of
f on
H is determined numerically.
View full abstract
-
Shigehiko Nonaka
1992 Volume 61 Issue 5 Pages
1449-1452
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
In order to determine electromagnetic (EM) eigenmodes for radio-frequency (RF) plasma productions between a pair of large-area electrodes, normal EM modes propagating in a region between a planar waveguide with one plasma and two dielectric layers are analyzed. Exact solutions are obtained by solving Maxwell’s equations. It is concluded that plasmas higher than a critical value of electron plasma frequency will be produced by an odd surface wave SW
o and less than the critical value, by two transverse-magnetic (TM) odd EM modes, TM
01 and TM
10.
View full abstract
-
Kunihiro Sato, Fujio Miyawaki
1992 Volume 61 Issue 5 Pages
1453-1456
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The electrostatic sheath and the heat flow of a two-electron-temperature plasma in the presence of electron emission are investigated analytically. It is shown that the energy flux is markedly enhanced to a value near the electron free-flow energy flux as a result of considerable reduction of the sheath potential due to electron emission if the fraction of hot electrons at the sheath edge is much smaller than one. If the hot- to cold-electron temperature ratio is of the order of ten and the hot electron density is comparable to the cold electron density, the action of the sheath as a thermal insulator is improved as a result of suppression of electron emission due to the space-charge effect of hot electrons.
View full abstract
-
Takashi Nagatani
1992 Volume 61 Issue 5 Pages
1457-1460
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
A growth model governed by the Poisson equation is presented to simulate the aggregation process in sputter (or vapor)-deposited thin films. By using computer simulation, it is found that the fractal dimension of the aggregates is consistent with that of diffusion-limited aggregation (DLA) at an initial stage and increases with time. The multifractal structure of the growth probability distribution is derived by making use of the Monte Carlo estimation. It is shown that the Poissonian growth pattern has characteristic fractal and multifractal properties.
View full abstract
-
Hideaki Kitazawa, Christina Schank, Stephan Thies, Berthold Seidel, Ch ...
1992 Volume 61 Issue 5 Pages
1461-1464
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
We report the first measurements of the electrical resistivity, the magnetic susceptibility and the specific heat of the new hexagonal compound CePd
2Al
3. The results indicate that CePd
2Al
3 is a new heavy fermion system with an electronic specific heat coefficient (γ) of 380 mJ/mol·K
2 and antiferromagnetic ordering below
TN=2.8 K.
View full abstract
-
Kiyosi Motida
1992 Volume 61 Issue 5 Pages
1465-1468
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
For those high-
Tc Cu-oxides whose crystalline unit is composed of a metal (M
c) sheet sandwiched by two pyramidal CuO
2 planes, a phonon-mediated superconductivity model is proposed in which a phonon having a change in the coordination number of a vibrating ion induces a charge-density wave in the CuO
2 plane. The electron-phonon coupling constant in this mechanism is estimated and is shown to resonably reproduce the observed dln
Tc⁄d ln
r value given earlier (J. Phys. Soc. Jpn.
60 (1991) 3194) on the basis of the Eliashberg theory, where
r denotes the M
c–O bond length.
View full abstract
-
Setsuo Mitsuda, P. M. Gehring, G. Shirane, Hideki Yoshizawa, Yoshichik ...
1992 Volume 61 Issue 5 Pages
1469-1472
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Neutron diffraction studies reveal the presence of two incommensurate magnetic phases (IC
1 and IC
2) between the paramagnetic and antiferromagnetic (AF) phases of the rare-earth compound NdIn
3, in a narrow temperature range just below
TN=6 K, where the collinear magnetic moments parallel to the tetragonal
c axis are rectangularly modulated along the
c axis. With decreasing temperature, the modulation wave number changes discontinuously from ∼0.04
c* in the IC
1 phase through ∼0.016
c* in the IC
2 phase to 0
c* in the AF phase.
View full abstract
-
Takao Ebihara, Izuru Umehara, Ariane Keiko Albessard, Kazuhiko Satoh, ...
1992 Volume 61 Issue 5 Pages
1473-1476
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
From de Haas-van Alphen experiments of CeIn
3 and LaIn
3, we have confirmed that the product of the cyclotron mass and the inverse scattering lifetime is constant.
View full abstract
-
Hideki Tou, Masahiro Matsumura, Hideki Yamagata
1992 Volume 61 Issue 5 Pages
1477-1480
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
In (La
1−xBa
x)
2CuO
4, the Cu-NQR spectra for
x=0.0625 and
x=0.08 were observed in each phase of the crystal structure. The temperature dependence of the spin echo decay rate,
T2−1, was also measured from 1.5 K to 300 K for both samples. The two well-separated sets of NQR spectra were observed in the high-temperature tetragonal (HTT) and low-temperature orthorhombic (LTO) phases in both samples. The spectrum at 1.5 K in the low-temperature tetragonal (LTT) phase for
x=0.0625 is abnormally broadened compared to the spectra in the HTT and LTO phases, and
T2−1 shows strong divergence at about 35 K. These two abnormal static and dynamical results indicate that the electronic state of the Cu atom changes from a nonmagnetic to magnetic one in the LTO→LTT transition, and some magnetic phase transition occurs at about 35 K which is lower than the LTT transition temperature, 60 K.
View full abstract
-
Masayuki Hagiwara, Koichi Katsumata
1992 Volume 61 Issue 5 Pages
1481-1484
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
From electron spin resonance (ESR) and magnetization measurements on a single crystal sample of the
S=1 linear-chain Heisenberg antiferromagnet Ni(C
2H
8N
2)
2NO
2ClO
4 (NENP), we have found the presence of the
S=1⁄2 degrees of freedom. We observed six ESR lines in this sample, four of which are the same as those observed in NENP doped with the nonmagnetic atoms by Glarum
et al. The temperature dependence of the intensity of the ESR signal is compared with the recent theory presented by Mitra
et al.
View full abstract
-
Masao Nomura
1992 Volume 61 Issue 5 Pages
1485-1494
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Co-variant quantum group algebras, exploited as
q-tensor formalism in previous papers, are rewritten in viewpoint of exchange algebras which obey co- and contravariant transformations. The formalism emphasizes unified treatment of transformation matrices, constituting quantum matrix groups, and basis functions.
View full abstract
-
Sadayoshi Toh, Hiroshi Iwasaki
1992 Volume 61 Issue 5 Pages
1495-1504
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
One-dimensional complex Ginzburg-Landau equation is examined numerically. Three types of turbulent states are observed as dissipative effects decrease. The first state is a weak chaos driven by modulational instability. The second one is a turbulent state characterized by the occurrence of relatively small bursts. The last one is a strongly intermittent turbulence dominated by bursts which blow up, getting close to a singular solution of the 1D nonlinear Schrödinger equation, till dissipation starts to work.
View full abstract
-
Masanori Aoki
1992 Volume 61 Issue 5 Pages
1505-1511
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Unharmonic vibrations of a one-dimensional diatomic lattice which has a mass impurity are investigated by computer simulation. We obtain stable localized mode vibrations for symmetric potentials.
View full abstract
-
Seizo Watarai, Keizo Yamamoto, Akira Nakanishi
1992 Volume 61 Issue 5 Pages
1512-1519
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Monte Carlo simulations are performed on the square lattice Ising system with both the nearest neighbor and the two-dimensional dipolar interactions in order to investigate the critical property of ferromagnetic phase transitions in this 2-dimensional system. Applying the finite size scaling theory to Monte Carlo data just near the transition point, the critical indices of this dipolar system are calculated and α=0.31±0.04, β=0.20±0.02, γ=1.08±0.20 and ν=0.72±0.10 are obtained. However, in the temperature region considerably far from the transition point, different values of α, β and γ seem to be adequate, which are rather close to those of the rigorous result of the 2-dimensional Ising model.
View full abstract
-
Kazuyosi Ikeda, Kunisuke Nisizima
1992 Volume 61 Issue 5 Pages
1520-1526
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The exact expressions for the volume-dependent cluster sums
bl with
l≤5, as functions of λ and
T(=temperature), are obtained for the two-dimensional triangular lattice gas (with nearest-neighbour interaction) of triangular shape with number of lattice sites (or volume) λ(λ+1)⁄2. The behaviour of the
bl for the case of attractive interaction is studied, and on the basis of the results, the phase transition (condensation) of this lattice gas is discussed by employing Ikeda’s theory of condensation of systems with volume-dependent cluster integrals.
View full abstract
-
Kunisuke Nisizima, Kazuyosi Ikeda
1992 Volume 61 Issue 5 Pages
1527-1534
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The exact expressions for the volume-dependent irreducible cluster sums β
k with
k≤7 for the one-dimensional, the two-dimensional square and the three-dimensional simple cubic lattice gas and with
k≤4 for the two-dimensional triangular lattice gas, with nearest-neighbour interactions, are obtained. Graphs expressing the volume dependence of β
k⁄β
k(0) in the case of attractive interaction are described, where β
k(0) is the limit of β
k for infinite volume. By the use of these results, the phase transition (condensation) of the lattice gases are discussed.
View full abstract
-
Il-Tong Cheon
1992 Volume 61 Issue 5 Pages
1535-1538
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
It is shown that the discretized photon propagator gives the zeroth order term of the Feynman integral calculated with a full relativistic photon propagator proposed by Bordag
et al.
View full abstract
-
Kazumi Suematsu, Toshihiko Okamoto
1992 Volume 61 Issue 5 Pages
1539-1548
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
With the aid of the enumeration method, a rigorous solution which involves ring formation is derived for a particular branching model
A−
R−
Bf−1. The solution provides an unexpected result of ring size distribution: The system yields less abundance of rings than a linear system. The bigger the ring size and the larger the functionality, the lesser the yields. In a concentrated solution, however, the concentrations of smaller
x-sized rings can approximately be expressed as [
Rx]=(
kRx⁄
kL)·
DAx⁄
x, where
kRx denotes the cyclization rate constant of an
x-sized chain,
kL an interconnection rate constant and
DA the extent of reaction of A functional units, respectively.
The result is closely related to the shape of clusters (
Lx) which still possesses the classical form under strong ring formation. However, the numerical solution shows that the classical Flory formula of size distribution does not work in general.
View full abstract
-
Toshihiro Okamoto, Masanobu Haraguchi, Masuo Fukui
1992 Volume 61 Issue 5 Pages
1549-1555
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We have theoretically analysed the optical bistability due to the excitation of surface plasmon polaritons (SP’s) in samples, prism/metal film/nonlinear optic medium and prism/gap material/metal film/non-linear optic medium, where the non-linear optic medium has an intensity-dependent refractive index. We considered two cases, i.e. non-linearity along the propagation direction of SP’s and along the normal to the interface. In the former case, the critical input power for the optical bistability was too high to allow experimental observation, while it was reasonably low for the latter case.
View full abstract
-
Jan Awrejcewicz, Tsuneo Someya
1992 Volume 61 Issue 5 Pages
1556-1559
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The occurrence of a Smale’s “twisted” horseshoe is discovered in a self-excited roll-slide mechanical oscillator. Some details concerning the investigated system as well as numerical analysis support the considerations.
View full abstract
-
Setsuko Mukai, Masahiro Nakagawa
1992 Volume 61 Issue 5 Pages
1560-1564
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
In this work, let us investigate anchoring effects on the layer structure in compressible smectic phases. The layer anchoring force is taken into account in an analysis of the chevron layer structure in the smectic phase. Our numerical results show that the anchoring strength comparable to (elastic coefficient)/(penetration length) is enough to orient the molecules at the boundary to such a preferred direction as the SiO columns evaporated on the bounding plates. In a weak anchoring limit, the present result is reduced to the previous one corresponding to the chevron layer structure. In a strong anchoring limit with a small pretilt angle at the boundaries, however, a quasi bookshelf layer structure is found to be realised.
View full abstract
-
Fumiko Negishi-Tsuboi
1992 Volume 61 Issue 5 Pages
1565-1579
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The characteristics of the waves in the ion-cyclotron range of frequency (ICRF) in a bumpy torus having a strong non-uniform magnetic field both in the toroidal and the radial directions are investigated experimentally. Several effects of the strong non-uniformity on propagation, damping and radial profile of the ion cyclotron wave are observed; the split of the dispersion curves for
m=0, ±1 modes, the wave damping depending on the modes
m and on the frequency even below the cyclotron frequency and the peaking of the poloidal component of the wave field slightly inside the cyclotron resonance layer. These strong non-uniform characteristics are compared with the two-dimensional wave field calculation using the finite-element method.
View full abstract
-
Hironobu Kasano, Masaki Takesada, Hiroyuki Mashiyama
1992 Volume 61 Issue 5 Pages
1580-1584
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The phase transition from the paraelectric phase (α phase) to the ferroelectric one of monoclinic K
2ZnBr
4 at about 159 K is investigated by means of X-ray diffraction. The space groups of the para- and ferroelectric phases are confirmed to be
P2
1⁄
m and
P2
1, respectively. The crystal structures of both phases are also determined at 296 and 123 K, respectively. In the paraelectric phase, the displacive and the disordered models are examined: The significance test shows that ZnBr
4 tetrahedron is in disorder. In the ferroelectric phase, ZnBr
4 tetrahedron is ordered and two independent potassium ions are translated in a same direction along the
b-axis.
View full abstract
-
Masanori Inui, Shin’ichi Takeda
1992 Volume 61 Issue 5 Pages
1585-1589
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The structure of liquid Bi–Ga alloys has been examined by neutron scattering measurements. The structure factors of this system have been obtained along the liquidus curve and also at higher temperatures above the critical temperature where the miscibility gap closes. A remarkable change in the structure factor has been observed at around 70 at.%Ga, which composition corresponds to the maximum temperature in the curve where miscibility gap closes. This concentration variation of the observed structure factors has been discussed in view point of the thermodynamic properties.
View full abstract
-
Takanao Asahi, Katsuhiko Hasebe, Kazuo Gesi
1992 Volume 61 Issue 5 Pages
1590-1597
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The crystal structure of [N(CH
3)
4]
2CdBr
4 was studied at 21°C in the room temperature phase and at −3, −8, −35, −80 and −115°C in the low temperature phase by single crystal diffractometry. In the room temperature phase, CdBr
4 ion and two kinds of N(CH
3)
4 ions were determined to be in disorder from Fourier synthesis and the significance test. In the low temperature phase, the occupation probabilities of ions as well as positional and thermal parameters were determined. The structure is characterized by two kinds of chains composed of CdBr
4 and N(CH
3)
4; one is along [001] and the other is along [100]. The deviation
Δβ of monoclinic angle β from 90° shows the characteristic temperature dependence as reported in [N(CH
3)
4]
2ZnBr
4 and [N(CH
3)
4]
2CoBr
4;
Δβ increases rapidly just below the transition temperature then decreases almost linearly as temperature decreases and changes its sign at about −72°C.
View full abstract
-
Hidetsugu Kitatani, Takehiko Oguchi
1992 Volume 61 Issue 5 Pages
1598-1605
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The value of the critical exponent ν of the two-dimensional ±
J Ising model along the ferromagnetic-nonferromagnetic phase boundary in the
p-
T plane (
p is the concentration of +
J bonds;
T is the temperature) has been calculated by the use of the transfer matrix method and the Roomany-Wyld approximation for long strips with finite width (
L×10
5:
L≤18), and has been found to take almost constant value, 1.0, at temperature above the Nishimori line. By the same method, a lower bound of the critical concentration between paramagnetic phase and the random antiphase state (RAS phase) has been calculated at some temperature below the Nishimori line in the
p-
T plane.
View full abstract
-
Igor N. Flërov, Toshihisa Yamaguchi, Shozo Sawada, Michail V. Gor ...
1992 Volume 61 Issue 5 Pages
1606-1608
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Using the adiabatic calorimeter the heat capacity of K
2ZnCl
4 and K
2CoCl
4 crystals was measured in temperature range 100∼300 K. The entropy change for ferroelastic phase transition was estimated to be
ΔS=0.34 (Zn) and 0.33 (Co) J·mol
−1·K
−1. The effect of hydrostatic pressure on the phase transition was investigated for both crystals.
View full abstract
-
Kazuyuki Matsumoto, Yoshikazu Abe, Anju Sawada
1992 Volume 61 Issue 5 Pages
1609-1614
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The Stipdonk-Hetherinton model for magnetism of solid
3He is investigated by the Monte Carlo method. Mean-field analysis is also examined for comparison. Using a finite size scaling, we found that the phase transition from the paramagnetic phase to the high field phase is λ-type. The phase boundary in H–T plane is determined by this finite size scaling analysis.
View full abstract
-
Fusayoshi J. Ohkawa
1992 Volume 61 Issue 5 Pages
1615-1632
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The Hubbard model is studied for the Mott-transition region in the limit of high dimension
d→+∞. Leading-order effects with respect to 1⁄
d are local spin fluctuations, all of which are fully included in the single-site approximation (SSA). Because the SSA is reduced to solving the Anderson model, it is argued that a normal heavy-electron liquid forms through the Kondo effect. The Fermi-liquid relations are proven within the SSA. The other leading-order effects are mean fields of magnetism caused by exchange interaction. Therefore it depends on the competition between the Kondo effect and the exchange interaction which the ground state is, magnetic or paramagnetic. However, any other effect is a higher-order effect. The 1⁄
d expansion from the heavy-electron liquid in the SSA is one of the most useful methods in examining lower-temperature phases in the real dimension.
View full abstract
-
Izuru Umehara, Takao Ebihara, Nobuyuki Nagai, Kazuhiko Satoh, Yutaka F ...
1992 Volume 61 Issue 5 Pages
1633-1644
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We have measured the magnetoresistance and de Haas-van Alphen (dHvA) effect in both the antiferromagnetic and paramagnetic states of NdIn
3. Many dHvA branches are detected in the dHvA experiments. Among them, a nearly spherical Fermi surface in the paramagnetic state, which corresponds to a band 7-electron Fermi surface of the non-4
f reference compound LaIn
3, is changed in the antiferromagnetic state into a multiply connected Fermi surface with necks. The cyclotron masses of NdIn
3 are in the range of 0.30
m0 to 1.05
m0, which are twice as large as those of LaIn
3.
View full abstract
-
Hiromi Otsuka
1992 Volume 61 Issue 5 Pages
1645-1656
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We investigate the ground state properties of the one- and the two-dimensional Hubbard models using a new variational Monte Carlo method. By generalizing the Gutzwiller variational wave function (GF) to take into account an off-diagonal intersite correlation, we examine the metal-insulator transition mechanism at the half filling. As Kaplan
et al. first pointed out, the binding mechanism between doubly occupied sites and empty sites plays a crucial role for this transition; we confirm this by examining the real space correlation function between these two kinds of sites. Results for the spin and the charge structure factors are presented as well as the momentum distribution function and are discussed in connection with the pairing effect. We also find that in less-than half filling, the improvements of the structure factors at 2
kF are realized as compared with GF results.
View full abstract
-
Yasumasa Hasegawa
1992 Volume 61 Issue 5 Pages
1657-1662
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Energy spectrum of electrons on three-dimensional lattice (two-dimensional lattices coupled with interlayer hoppings) in the magnetic field along the (1, 1, 1) direction is investigated. The two-dimensional Hofstadter’s gaps become small as the electron hoppings between layers are increased. It is found that the critical value of the interlayer hoppings at which the largest gap is zero is close to the value of hoppings in the layer except for the small
q, where
q is the denominator of the flux through each unit square, φ=
p⁄
q. This means that a finite gap is opened by a small anisotropy in the simple cubic lattice. The effects of the next-nearest-neighbor and third-nearest-neighbor (diagonal) hoppings are also investigated.
View full abstract
-
Kozo Hoshino, Mitsuo Watabe
1992 Volume 61 Issue 5 Pages
1663-1669
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The electron density distribution and the electron-ion correlation functions in liquid sodium are calculated within the linear screening approximation based on the pseudopotential perturbation theory. The ionic configuration of the liquid is obtained by the molecular dynamics simulation method. The calculated electron-ion structure functions are compared with recent experimental results.
View full abstract
-
Chikara Sugiura
1992 Volume 61 Issue 5 Pages
1670-1675
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The
Kα emission and
Kβ emission spectra in fluorescence of Cl
− in NH
4Cl are measured with a two-crystal vacuum spectrometer. The Cl
− Kβ emission spectrum is presented along with the Cl
− K absorption, Cl
− L2,3 absorption and vacuum ultraviolet (VUV) absorption spectra of NH
4Cl, reported previously. By using the measured emission spectra and the VUV absorption spectrum, the energy position of the bottom of the conduction band is shown in the Cl
− K absorption and Cl
− L2,3 absorption spectra. The first sharp peak of the Cl
− L2,3 absorption is identified as being due to a core exciton, the energy level of which is formed below the bottom of the conduction band. The binding energy of the exciton is estimated to be 1.1(±0.1) eV. The second sharp peak is related to two types of excitons; a stable exciton and a metastable exciton.
View full abstract
-
Yoshiyuki Ono, Seiichi Fukuda
1992 Volume 61 Issue 5 Pages
1676-1684
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The quantum Hall effect is studied in terms of the random matrix model, which has been recently proposed and proved to be quite powerful in investigating the electronic structures in strong magnetic fields. The effective potential felt by electrons in the lowest Landau subband is reconstructed from the random matrix elements. This reconstruction shows that even if we assume short-ranged potentials in making the random matrix, the effective potential has a finite correlation length of the order of the magnetic length. The equilibrium current is confirmed to flow along the equipotential lines of this effective potential. The Hall conductivity and the distribution of the Hall current are calculated within the random matrix model. The results are consistent with previous ones obtained by standard method, i.e. by directly defining the random potential.
View full abstract
-
Yositake Takane, Hiromichi Ebisawa
1992 Volume 61 Issue 5 Pages
1685-1690
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Simple conductance formula for small systems with a single superconducting segment is derived through the linear response theory. It is an extension of the Landauer formula. The expression consists of the usual transmission and reflection coefficients as well as the off-diagonal elements which are given by the processes where an electron is reflected to a hole due to the Andreev reflection.
View full abstract
-
Junichi Wakabayashi, Shinji Kawaji, Takayuki Goto, Tetsuo Fukase, Yoji ...
1992 Volume 61 Issue 5 Pages
1691-1700
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Quantum transport experiments of Si-MOS inversion layers have been done at temperatures between 50 mK and 1.45 K and in magnetic fields between 14 and 23 T using samples having two grades of electron mobility. The Hall conductivity were analyzed employing a model calculation to derive the temperature dependence and the magnetic field dependence of the mobility edge. At low temperatures, the mobility edge was independent of temperature and independent of magnetic field suggesting the mobility edge is dominated by a macroscopic potential fluctuations. The temperature dependence of the mobility edge at high temperatures can not be explained by the existing theory of localization in Landau subbands in two dimensional systems and that of the temperature dependence of the inelastic scattering in the zero magnetic field.
View full abstract
-
Shoji Mimotogi, Taizo Masumi
1992 Volume 61 Issue 5 Pages
1701-1708
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
In contrast with monotonous increase expected on the basis of virtual crystal approximation, anomalous reduction of electron-LO phonon interaction has been observed in cyclotron resonance experiments on the photoexcited electrons in the AgCl
xBr
1−x (0<
x≤0.21) mixed crystals at
T=4.2 K and
f=35 GHz with increasing
x. For the first time, we have experimentally determined the values of Fröhlich coupling constant α in mixed crystals. Because there exist two LO-phonon modes in the AgBr-rich region, the reduction of electron-LO phonon interaction can not be explained by the virtual crystal approximation where disorders are simply averaged, and invokes the need of further theoretical studies.
View full abstract
-
K. K. Maurya, S. A. Hashmi, S. Chandra
1992 Volume 61 Issue 5 Pages
1709-1716
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
A new proton-conducting polymer electrolyte polyethylene oxide (PEO)+(NH
4)
2SO
4 has been reported. The proton transport in solution-cast films of PEO complexed with (NH
4)
2SO
4 has been established using optical microscopy, XRD, DTA, IR, coulometry, transient ionic current and electrical conductivity studies. The highest electrical conductivity has been found to be 9.3×10
−7 S·cm
−1 for the NH
4+/EO ratio equal to 0.0416. The transference number and mobility of protonic movement have been found to be
tH+\simeq0.61 and μ
H+\simeq2.9×10
−7 cm
2/volt-sec, respectively. The movement of anions (possibly HSO
4−) also contribute to the overall conductivity.
View full abstract
-
Ayao Okiji, Hideaki Kasai, Kunihiro Mitsutake
1992 Volume 61 Issue 5 Pages
1717-1723
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Magnetic field and Fermi energy dependences of conductance in a quantum wire with a small ring geometry are calculated numerically with the use of the coupled channel method. As a function of the Fermi energy or magnetic field, the conductance shows various pattern behaviours, of which the origin is discussed on the basis of the numerical results. The conductance shows oscillations as a function of magnetic flux passing through the effective area enclosed by the ring part. A value of the oscillation period as a function of the magnetic flux is given by
Φ0=
h⁄
e approximately if the effective area enclosed by the ring part is estimated as an area enclosed by the potential energy minimum curve.
View full abstract
-
Nobuhisa Fujima, Tsuyoshi Yamaguchi
1992 Volume 61 Issue 5 Pages
1724-1729
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
By using the DV–Xα–LCAO method, electronic states are calculated for Co
12V, Co
13 and Co
12MH
2 (M=V, Cr, Mn, Fe and Co) clusters. The gross feature of electronic states of the icosahedral Co
12V cluster is similar to that of the icosahedral Co
13 cluster. The Co
12VH
2 and Co
13H
2 clusters are different from each other in the electronic structure of the levels which contain much 1
s atomic orbital of H atom. The 1
s orbital of H atom interacts weakly with the 3
d orbital of the exterior Co atoms and makes a non-bonding orbital in the Co
12VH
2 cluster, but it interacts strongly and makes a bonding orbital in the Co
13H
2 cluster. These facts explain the experimental results that H molecules are hardly adsorbed to a Co
12V cluster, but easily adsorbed to a Co
13 cluster. The electronic structure of the Co
12MH
2 clusters gradually changes as the sort of the center atom M varies from V to Co atoms in the 3
d transition-metal series.
View full abstract
-
Nobuyuki Ogawa, Manfred Sigrist, Kazuo Ueda
1992 Volume 61 Issue 5 Pages
1730-1741
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The multiple phase transition behavior of unconventional superconductivity confined in a thin film is investigated considering the example of a two component superconducting order parameter. First the series of possible superconducting phase transitions are discussed on the basis of a group theoretical analysis. Then the corresponding Ginzburg-Landau theory is used to derive the conditions for the occurrence of at least double transitions. Finally, the specific heat and the magnetic susceptibility are analized as possible quantities to detect multiple phase transitions. The latter also provides a method to distinguish between time-reversal conserving and time-reversal breaking phase transitions.
View full abstract
-
Yuji Yamaguchi, Madoka Tokumoto, Shinya Waki
1992 Volume 61 Issue 5 Pages
1742-1750
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Magnetic susceptibility of YBa
2Cu
3−xCo
xO
y (
x=0.06∼0.3 with tetragonal structure) has been studied, being focused on the successive antiferromagnetic transitions,
TN2 and
TN3, where the susceptibility(χ)-
versus-temperature(
T) curve has kinks. The
TN2, ranging between 18 K and 90 K, was nearly proportional to
x, but little dependent on
y. The
TN3, near 6 K, was almost independent both on
x and
y. The transitions were analyzed based on a molecular field approximation, as secondary antiferromagnetic transitions accompanying a magnetic order of Co ions in the chain site. The characteristics of these transitions have been well explained with parameters of
J0=1400 K, |
J1|≅160 K,
J2+8
D=(180±60) K, and
J4=(80±40) K; where the parameters are exchange interactions between Cu
2+ spins (
J0,
J2), between Cu
2+ and Co
3+ spins (
J1), between Co
3+ spins (
J4) and a crystalline magnetic anisotropy (
D). The good fitting of the model suggests that these magnetic orders are inherent in the YBa
2Cu
3O
y structure.
View full abstract
-
Yoshichika \={O}nuki, Sung Won Yun, Isamu Ukon, Atsushi Kobori, Izuru ...
1992 Volume 61 Issue 5 Pages
1751-1757
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
We have studied the electrical and magnetic properties of U–X (X=Ru, Rh and Ir) intermetallic compounds by measuring the electrical resistivity, Hall coefficient, thermoelectric power, specific heat, magnetic susceptibility and magnetization. We have found a variety of behaviors of antiferromagnetism, ferromagnetism and superconductivity in these compounds.
View full abstract
-
Meiro Chiba, Yoshitami Ajiro, Hikomitsu Kikuchi, Satoru Maegawa, Takes ...
1992 Volume 61 Issue 5 Pages
1758-1771
Published: May 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The ordering process in the Ising-like Heisenberg antiferromagnet on the hexagonal lattice has been studied through the
133Cs NMR in CsNiBr
3. The observed local field at
133Cs was 3.5 times as large as the calculated field from the point dipoles at the Ni
2+ sites. The limited applicability of the conventional point dipole model has been overcome by treating the symmetry property at the
133Cs site. Under the applied field of 4.6 T, we have found that the Ni
2+ spin component parallel to the
c-axis orders below
TN1=15.0 K, whereas the perpendicular component orders below
TN2=12.5 K to form the triangular three-sublattices in the
c-plane: one spin is parallel to the
c-axis and the other two are canted ±38° from the
c-axis. The comparison is made with the existing data of CsNiCl
3 with an emphasis on the dynamical behavior of the triangular spin arrangement.
View full abstract
-
Tatsuo Kobayashi, Yoshitaka Tabuchi, Kiichi Amaya, Yoshitami Ajiro, Ta ...
1992 Volume 61 Issue 5 Pages
1772-1776
Published: May 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Heat capacity measurements of the quasi one-dimensional
S=1 antiferromagnet Ni(C
2H
8N
2)
2NO
2(ClO
4) are performed in static magnetic fields up to 13 T. Applying a magnetic field, a broad anomaly appears below 5 K, which reflects the gap energy between the nonmagnetic ground state singlet and the excited states. The field-dependence of the energy gap estimated from the measured heat capacities gives the critical field values close to those obtained in high-field-magnetization measurements and non-zero gap remaining at the critical field. Within our experimental range of temperature and magnetic field, we have not observed any sharp peaks corresponding to the expected three dimensional magnetic long range ordering.
View full abstract