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Koji Ohkitani
1992 Volume 61 Issue 3 Pages
757-761
Published: March 15, 1992
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Starting with analysis of a simple case of the inviscid Burgers equation, we raise the question of the title as a fundamental characterization of general inviscid fluid motion. In particular, formation of high vorticity-gradient regions in two-dimensional Euler flow is studied numerically both in physical space and in the Lagrangian marker space. Each singular structure is shown to be fixed in the marker space for some time, even though the strain and the vorticity gradient are not clearly separated in scale.
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Shun-ichi Kobayashi, Hidenori Goto, Shingo Katsumoto
1992 Volume 61 Issue 3 Pages
762-764
Published: March 15, 1992
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By measuring the Knight shifts of Cu NMR in small particles of Cu–Mn alloys with mean diameter of 60 A, we showed that the anomaly in the spin susceptibility due to the level quantization of conduction electrons can be suppressed by the spin scattering. The condition for sufficient suppression was τ
s<<
h⁄δ where τ
s is the spin scattering time and δ the mean level spacing.
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Satoshi Fujimoto
1992 Volume 61 Issue 3 Pages
765-769
Published: March 15, 1992
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We investigate the effects of electron correlation on the nuclear spin-lattice relaxation rate (
T1−1) and the Knight shift of high-
Tc superconductors. The main effects are a quasiparticle damping and the vertex enhancement of a spin susceptibility. The former involves a pair breaking effect induced by electron correlation, and brings about the suppression of the coherence peak. The latter is reduced by increasing gap below
Tc, and results in the sharp decrease of
T1−1 and the Knight shift. Taking into account these effects, we fit the temperature dependence of these quantities to the experimental results by assuming
s-wave or
d-wave BCS-like superconductivity. For
d-wave pairings, good fits can be obtained. In contrast, it is rather difficult to achieve a fit for
s-wave pairings.
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Yohsuke Yoshinari, Hiroshi Yasuoka, Yutaka Ueda
1992 Volume 61 Issue 3 Pages
770-773
Published: March 15, 1992
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The temperature dependence of the spin lattice relaxation rates (
T1−1) at the planar copper (Cu(2)) and oxygen (O(2, 3)) sites in High-
Tc superconductor; YBa
2Cu
3O
6.96 has been re-examined using an oriented powder sample. We have confirmed the existence of a characteristic region around
Tc where the degrees of suppression of both
T1−1’s are equivalent. At the lower temperature, the decrease of the relaxation rate at the Cu(2) sites was more rapid than that of the O(2, 3) sites, and obeyed the power law against the decrease of the O(2, 3) relaxation rate. This is in contrast with a previous report.
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Ryou Nakabayashi, Y\={u}ichi Tazuke, Shigeyuki Murayama
1992 Volume 61 Issue 3 Pages
774-777
Published: March 15, 1992
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Magnetism of Y
2Ni
7 and YNi
3 is studied. Linear and parallel
M2-vs-
H⁄
M plots and large Rhodes-Wohlfarth ratios are obtained, confirming itinerant electron weak ferromagnetism. Analysis of magnetization data using the self-consistent renormalization theory of Takahashi shows the validity of his theory and the importance of spin fluctuation in the present compounds.
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Toshiro Takabatake, Hiroshi Iwasaki, Hironobu Fujii, Shin-ichi Ikeda, ...
1992 Volume 61 Issue 3 Pages
778-781
Published: March 15, 1992
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Ternary uranium compounds UCu
2Sn and UAu
2Al have been found to crystallize in the hexagonal ZrPt
2Al- and orthorhombic YPd
2Si-type structures, respectively. Magnetic-susceptibility, electric-resistivity and specific-heat measurements reveal that UCu
2Sn, UPt
2Sn and UAu
2Al undergo antiferromagnetic transitions at 16.6, 60 and 25 K, respectively. With decreasing temperature below
TN, the resistivity of UCu
2Sn exhibits a pronounced peak, whereas those of the other two show a precipitous drop. The extrapolated value of
C⁄
T at 0 K ranges from 17 mJ/K
2 mol for UPt
2Sn to 102 mJ/K
2 mol for UAu
2Al.
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Masayoshi Tajiri, Yushi Fujimura, Youichi Murakami
1992 Volume 61 Issue 3 Pages
783-790
Published: March 15, 1992
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There are two types of singular interactions between algebraic soliton and
y-periodic soliton (i.e. the array of the localized structures in the
y-direction, which propagates in the
x-direction): one is the resonant interaction where the algebraic soliton joins in the line of
y-periodic soliton after collision, while the other is the extremely repulsive interaction where the algebraic soliton affects the motion of the
y-periodic soliton infinitely apart. Both interactions are associated with the boundary between attractive interaction and repulsive one in the parameter space.
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Youichi Murakami, Masayoshi Tajiri
1992 Volume 61 Issue 3 Pages
791-805
Published: March 15, 1992
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The exact solutions to the Kadomtsev-Petviashvili equation with positive dispersion are analysed to study the interaction between line soliton and
y-periodic soliton (i.e. the array of the localized structures in the
y direction, which propagates in the
x direction). The interactions are classified into several types according to the phase shifts due to collision. There are two types of singular intearctions: one is the
resonant interaction that generates one line soliton while the other is the
extremely repulsive or
long-range interaction where two solitons interchange each other
infinitely apart. Both interactions are associated with the parametric points on the boundary between the regions, where the
transverse phase shift can occur and that for no transverse phase shift. Detail behaviors of interactions are illustrated graphically and the differences from the singular interactions in other cases are described.
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Norio Konno, Makoto Katori
1992 Volume 61 Issue 3 Pages
806-811
Published: March 15, 1992
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A class of the attractive nearest-particle systems with finite ranges is studied. By using the correlation identities and the FKG inequality, the rigorous upper bounds ρ
λ(2) for the order parameters of this class are obtained. Furthermore, it is shown that the rigorous lower bounds λ
c(2) for the critical values of it are strictly greater than one.
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Shigeru Sasabe
1992 Volume 61 Issue 3 Pages
812-815
Published: March 15, 1992
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Self-field method suggested by the present author in the previous work is applied to the electron in the Coulomb potential. Effectively weakened Coulomb potential are found due to the self-field of the electron. The form of the weakened Coulomb potential between two electrons is
U(
r)=(
e2⁄4π
r)[1−exp (−
r⁄2
Rc) cos (
r⁄2
Rc)].
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Masahiro Ohgiwari, Mitsugu Matsushita, Tohey Matsuyama
1992 Volume 61 Issue 3 Pages
816-822
Published: March 15, 1992
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We have investigated the morphological change in colonies of bacteria called
Bacillus subtilis. Patterns of colonies grown on the surface of thin agar plates were found to change drastically through the variation of environmental conditions; concentrations of nutrient
Cn and agar
Ca in the agar medium. They were classified into five types; DLA-like, Eden-like, DBM-like, intermediate and homogeneously spreading. The active movement of individual bacterial cells was seen in expanding periphery of a colony at intermediate and low
Ca (soft agar medium). Such bacterial cell movements are found to induce the shift from DLA- and Eden-like patterns to those found for softer agar medium. Physical implication of the pattern changes is discussed.
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Masaki Hayashi, Juan J. Salazar
1992 Volume 61 Issue 3 Pages
823-826
Published: March 15, 1992
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We study the dimensional dependence of the hadronic level density (mass spectrum) in the (Abelian) bag model, using the microcanonical ensemble and show that it behaves asymptotically as ρ(
m)∼
cm−d exp (
m⁄
T0), where
d is the spatial dimension and
T0 is a limiting temperature.
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M. T. Ghoniem, A. El-Naghy, S. Saleh, M. Mohery
1992 Volume 61 Issue 3 Pages
827-832
Published: March 15, 1992
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In this work we present some general characteristics of inelastic interactions of 4.5 GeV/c/nucleon
3He projectile with emulsion nuclei. The presented characteristics are the multiplicity distribution of the produced shower particles in view of coherent and incoherent superposition models of heavy ion reactions, the correlations between production of these showers and the target nucleus excitation and fragmentation. A comparison between some of these interaction characteristics and their corresponding ones of other heavy ion reactions is made.
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Noriyoshi Nakajima, Masao Okamoto
1992 Volume 61 Issue 3 Pages
833-843
Published: March 15, 1992
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Neoclassical theories for the parallel flow, current and rotation are extended to a multispecies plasma in general toroidal systems. The extended theory is constructed in the Boozer coordinate system to be common in all collisionalities (1⁄ν, plateau, Pfirsh-Schlüter regime) in terms of the geometric factor. It is shown that the decisive difference between axisymmetric and non-axisymmetric toroidal systems is attributed to the geometric factor which reflects the breaking of axisymmetry. As a result it is first found that the neoclassical current driven directly by the radial electric field can exist in the non-axisymmetric device, whereas such the current vanishes in the axisymmetric torus. Explicit expressions for poloidal and toroidal rotations are first derived for a multispecies plasma in the non-axisymmetric toroidal system. In the limit of small geometric factor, the poloidal and toroidal rotations of ions are reduced to the usual diamagnetic and
E×
B drifts.
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Michio Matsumoto, Kazuo Sakai, Satoshi Takeuchi
1992 Volume 61 Issue 3 Pages
844-848
Published: March 15, 1992
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Low frequency waves excited in a positive column at pressures
p>0.1 Torr in a longitudinal magnetic field
B is theoretically analyzed. The field
B is strong but less than the critical field
Bc for the helical instability. These excited waves belong to the ionization wave which is affected by the field
B, and oscillation currents in the azimuthal and axial directions in the positive column synchronously coexist in those waves. The effect of those currents is to add a new term proportional to the wavenumber to the frequency of the ionization wave in the field
B.
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Sadayoshi Murakami, Tetsuya Sato
1992 Volume 61 Issue 3 Pages
849-862
Published: March 15, 1992
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Externally driven reconnection, assuming an anomalous particle collision model, is numerically studied by means of a 2.5D
macroscale particle simulation code in which the field and particle motions are solved self-consistently. Explosive magnetic reconnection and energy conversion are observed as a result of slow shock formation. Electron and ion distribution functions exhibit large bulk acceleration and heating of the plasma. Simulation runs with different collision parameters suggest that the development of reconnection, particle acceleration and heating do not significantly depend on the parameters of the collision model.
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Kiyomasa Watanabe, Yuji Nakamura, Masahiro Wakatani
1992 Volume 61 Issue 3 Pages
863-880
Published: March 15, 1992
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According to the neoclassical ripple transport, the positive radial electric field state of
Er>0 is favorable to obtain a good confinement compared to the negative radial electric field state of
Er<0. The radial electric field depends sensitively on the density and the characteristic length of density gradient, and a relatively flat density profile is desirable to minimize a heating power to obtain
Er>0. Our transport code study shows that gross confinement time is improved about seven times compared to the LHD scaling when
Er>0 is achieved in the whole plasma region. Without control to keep the density profile relatively flat the confinement improvement reduces to about a factor of two compared to the LHD scaling. Heating power required to achieve
Er>0 in the whole plasma region is evaluated. Enhancement of the neoclassical ripple transport with increase of helical magnetic field ripple is favorable to reduce the heating power to achieve
Er>0 in the whole plasma region.
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Takashi Mochiku, Kazuo Kadowaki
1992 Volume 61 Issue 3 Pages
881-890
Published: March 15, 1992
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The crystal structure of Pb
2Sr
2MCu
3O
8 (M=Nd, Sm, Eu, Gd, Dy, Y
1−xCa
x, Ho and Er) has been analyzed by the Rietveld method of X-ray powder diffraction data. In order to best fit the data several structural models with the different space groups have been tried. Among them the two models with the space groups of Cmmm and P22
12 in which the oxygen atoms on the PbO sheet are displaced along the
b-axis from the midposition between Pb atoms within the PbO sheet gave the best results. It is shown that the lattice parameters and the interatomic distances vary with the ionic radius of lanthanoides. The systematic variation of the atomic arrangement in the unit cell which consists of stacking of sheets having a different role is argued in comparison with the prototype of the Ba
2LnCu
3O
6+δ system. The bond lengths of the constituent atoms are also argued with special emphasis on the local environment of two copper sites. In the Pb
2Sr
2(Y
1−xCa
x)Cu
3O
8 system, the interatomic distances change more largely by Ca-doping than by the effect of the size of the lanthanoide atoms.
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Kazutoshi Ohashi, Yoshiko H. Ohashi, Satoshi Imai, Mitsuru Fukuchi
1992 Volume 61 Issue 3 Pages
891-904
Published: March 15, 1992
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The phonon contribution to the resistive force acting on a moving dislocation is discussed, and an expression of the dislocation damping constant is obtained. The damping constant of a dislocation in an isotropic medium is expressed analytically. The theoretical results are also applied to anisotropic alkali halide crystals, and the numerical results are compared with the experimental results.
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Yukio Noda, Hirofumi Kasatani, Yukiho Watanabe, Hikaru Terauchi
1992 Volume 61 Issue 3 Pages
905-915
Published: March 15, 1992
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Structure analysis of K
3H(SO
4)
2 was performed by X-ray diffraction experiments at various temperatures down to 27 K in order to investigate the hydrogen bond character in connection with the geometrical isotope effect. The hydrogen bond length
ROO monotonically decreases with decreasing temperature, accompanied by the contraction of lattice parameters, and it crosses the critical bond length
rc(H) at about 100 K. Simultaneously, the double site feature of hydrogen atoms changes into the single site state at the center of the hydrogen bond. This behavior explains why K
3H(SO
4)
2 has no phase transition in spite of the existence of the disordered character at room temperature.
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Shinji Hayashi, Hiroki Sugano, Hiroshi Arai, Keiichi Yamamoto
1992 Volume 61 Issue 3 Pages
916-923
Published: March 15, 1992
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Temperature dependence of Raman scattering from gas-evaporated WO
3 has been investigated. From a comparison between the present Raman data and that of the bulk crystals, it is shown that the phase transition behaviors of the microcrystals are completely different from those of the bulk crystals. At room temperature, the possible phase of the microcrystals is the mixture of phases V and VII of the bulk crystals, which is supported by the X-ray diffraction measurements. At around 230 K, the microcrystals gradually undergo a phase transition, transforming into a new phase not reported so far or a mixture of phase VII and the new phase. Possible explanations for the phase mixture based on the size dependence of the Raman spectra are given.
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Tadao Ishii
1992 Volume 61 Issue 3 Pages
924-930
Published: March 15, 1992
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On the basis of the relaxation mode theory, the hopping conduction on fractal lattices is investigated by the direct use of a set of eigenvalues and eigenstates for the relaxational fractons, where the relaxational fracton is a hopping version of the vibrational fracton. The obtained conductivity formula gives us full information over all the frequency and temperature range. Especially at a frequency and temperature range, its frequency-dependence is identical to the result derived by Alenxander and Orbach for fractal and percolation lattices. This scheme of dealing with the relaxational fractons is quite useful for the study of dynamical properties in the hopping conduction: the quasi-elastic light scattering and ultrasonic attenuation are also discussed on the same ground.
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Nobuo Wada, Kaoru Ishioh, Takashi Watanabe
1992 Volume 61 Issue 3 Pages
931-936
Published: March 15, 1992
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Isosteric heat of sorption
qst and heat capacity
C of
3He and
4He adsorbed in the 10 Å-diameter pores of Na–Y zeolite have been measured as a function of the amount
n adsorbed.
qst at
T=0 K shows a step-wise decrease with increasing
n. This change suggests adsorption potential minima of 0.3 kJ/mol (36 K) in depth on the zeolitic pore wall that is caused by the electric dipole of Na
+ and (AlO
2)
−, and shows a first layer completion at
n=38% of full pore and multilayers at the larger amount
n adsorbed. At 38<
n\lesssim70% of full pore, one-dimensional gas with
C⁄
n∼4.15 J/K/mol or a liquid state of the second layer on the first solid layer is indicated by the heat capacity, even though the pore diameter is only a few times larger than that of the helium atom.
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Shugo Suzuki
1992 Volume 61 Issue 3 Pages
937-951
Published: March 15, 1992
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Effects of interaction between metallic electrons and local phonons on physical properties are investigated. Distribution function of the local oscillator is calculated by the Monte Carlo method. The adiabatic potential becomes a double well when the interaction is sufficiently strong. It is shown that the tunneling motion between the two minima of the adiabatic potential is suppressed by the non-adiabatic effects. Also we study the consequences of the double well on specific heat and electrical resistivity. It is found that the presence of the double well results in anomalous behaviors of these quantities.
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Fusayoshi J. Ohkawa
1992 Volume 61 Issue 3 Pages
952-959
Published: March 15, 1992
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The optical conductivity of the Hubbard model with strong electron correlation is examined in less-than and almost half-filled cases by assuming the formation of the Gutzwiller heavy-electron band (HEB) at the top of the lower Hubbard band (LHB), which is predicted by recent theories. The optical conductivity is the superposition of the Drude contribution within the HEB and excitations among the LHB, the HEB, and the upper Hubbard band (UHB). Their intensities are approximately proportional to 1−
n except the excitations from the LHB to the UHB,
n being the average number of electrons per unit cell. It is argued that the excitations from the LHB to the HEB are responsible for the anomalous spectra at mid-infrared frequencies of the optical conductivity and the Raman scattering of the high-temperature cuprate-oxide superconductors.
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Yoshichika \={O}nuki, Izuru Umehara, Ariane Keiko Albessard, Takao Ebi ...
1992 Volume 61 Issue 3 Pages
960-968
Published: March 15, 1992
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We have measured the magnetoresistance and de Haas-van Alphen (dHvA) effect in CeRu
2Si
2 and LaRu
2Si
2. From the results of magnetoresistance, CeRu
2Si
2 is concluded to be a compensated metal, possibly possessing an open orbit along the
c-axis of the tetragonal structure. On the other hand, LaRu
2Si
2 is an uncompensated metal, showing the saturated magnetoresistance. These results imply that the 4
f electrons in CeRu
2Si
2 are itinerant. In the dHvA experiments of LaRu
2Si
2, we have found a large ellipsoidal Fermi surface which occupies roughly half of the Brillouin zone in volume. On the other hand, CeRu
2Si
2 possesses multiply connected Fermi surfaces in part, although main Fermi surfaces are not observed yet.
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Masahiro Inoue, Tadashi Takemori, Hiroshi Miyazaki
1992 Volume 61 Issue 3 Pages
969-974
Published: March 15, 1992
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We have investigated the criterion for the trace-map trajectories to fall onto the quasi-invariant surface for the generalized Fibonacci lattice defined by the recurrence relation
D(
n+1)=
D(
n)
pD(
n−1)
q with positive integers
p and
q (
q≠1). It is shown that, at infinite generation, the energies corresponding to the quasi-invariant surface constitute a dense subset of the energy spectrum.
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Yasunari Kurihara
1992 Volume 61 Issue 3 Pages
975-982
Published: March 15, 1992
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The conductivity tensor components σ
zz and σ
xx are calculated for the electrons with the energy dispersion h
2(
kx2+
ky2)⁄2
m−2
t cos
kzc in the presence of a magnetic field which makes an angle θ with the
z axis in the
yz-plane. For ω
cτ>1, σ
zz and σ
xx show the oscillatory behavior in variation of tan θ, where ω
c is the cyclotron frequency of the electron and τ is the relaxation time of it. For ω
cτ<1, they have non-oscillatory properties with respect to tan θ and reproduce results which have been got in use of a semi-classical treatment.
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Satoru J. Miyake
1992 Volume 61 Issue 3 Pages
983-988
Published: March 15, 1992
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The staggered magnetization of the Heisenberg antiferromagnet on triangular lattice is calculated by means of the usual spin-wave theory. The magnetization is derived from the ground-state energy as its derivative with respect to the staggered field, and given in a form of 1⁄
S expansion,
S being the magnitude of spins. The second-lowest correction, a term of
O(1⁄
S), consists of two contributions; one from the first-order effect of four-boson terms in the Hamiltonian, and another from the second-order perturbation due to a three-boson term. Each contribution diverges when the exchange interaction is isotropic, but the divergent parts of the two contributions are found to cancel, leaving a finite result for the staggered magnetization to this order. Numerical result for the staggered magnetization is
S−0.2613+0.0055⁄
S.
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Hiroshi Shimahara, Satoshi Takada
1992 Volume 61 Issue 3 Pages
989-997
Published: March 15, 1992
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The two dimensional (2D)
t-
J model is studied in a Green’s function decoupling scheme, which is an extension of the Kondo and Yamaji’s theory (KY theory). The KY theory was originally proposed for spin systems, and is applicable to cases in which there is no symmetry breaking. We derive the lowest order corrections by the electron hopping energy
t to self-consistent equations for the correlation function. Hole concentration dependences of the antiferromagnetic (AF) long-range-order (LRO) and spin correlation length at zero temperature are obtained. It is found that they decrease sensitively with doping holes even in a situation very favorable for the antiferromagnetism. The critical hole concentration at which AF LRO vanishes is estimated to be much smaller than in the three-dimensional case. A characteristic feature of 2D electron systems with strong correlations is discussed.
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Toshihiko Suzuki, Yuhei Natsume
1992 Volume 61 Issue 3 Pages
998-1010
Published: March 15, 1992
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The expression of magnon Raman scattering for the case where the sublattice magnetization vanishes by the quantum effect is made for the Heisenberg antiferromagnetic system on a square lattice by the method of modified spin wave, on the basis of the exchange scattering mechanism. We discuss both cases with and without the frustration induced by the exchange interaction for the second nearest neighbor. The numerical calculation for Raman spectra succeeds the theoretical development. Though the quantum fluctuation is expected to be quite strong, it should be stressed that Raman spectra can be expressed as magnon scattering by the exchange scattering mechanism. However, the main peak for two magnon process in those spectra is essentially accompanied by the side peak reflecting four magnon process of the modified spin wave.
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Hidetoshi Nishimori
1992 Volume 61 Issue 3 Pages
1011-1012
Published: March 15, 1992
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It is proved that the critical concentration
pc of ferromagnetic bonds below which no ferromagnetic phase exists in a non-Ising ±
J model is equal to or larger than that of the Ising ±
J model on the same lattice. I also develop an argument that
pc is universal for the ±
J model with any type of spin on any specified lattice.
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Kazuo Hida
1992 Volume 61 Issue 3 Pages
1013-1018
Published: March 15, 1992
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The quantum disordered state (QDOS) of the spin 1/2 double layer square lattice Heisenberg antiferromagnet is studied. Using the dimer expansion from the limit of the large interlayer coupling
J′, the staggered susceptibility χ, the antiferromagnetic structure factor
Sπ and the antiferromagnetic correlation length ξ are calculated up to the 6-th order in the intralayer coupling
J. The ratio analysis shows that the QDOS becomes unstable against the Néel ordering at
J′⁄
J\simeq2.56. The critical exponents are not inconsistent with the universality class of the 3-dimensional classical Heisenberg model, suggesting that our QDOS corresponds to that expected in the 2-dimensional square lattice Heisenberg antiferromagnet with unphysically small spin (<0.276). The results of the projector Monte Carlo simulation also confirms the dimer expansion results.
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Koichi Kindo, Yoshiaki Chiba, Yoshikazu Hidaka, Muneyuki Date
1992 Volume 61 Issue 3 Pages
1019-1024
Published: March 15, 1992
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Anomalous electron spin resonance observed in Nd
2CuO
4 is attributed to antiferromagnetic resonance (AFMR) of Nd spins in the Nd–Cu spin network. The anomaly comes from the staggered field due to Cu spins on the Nd-site. The Cu spins form a tight antiferromagnetic spin network and are almost at rest during the Nd-resonance. The staggered field acts as an additional anisotropy field on the Nd spin. Various magnetic parameters in AFMR are in accord with those determined by the high field magnetization study.
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Kazuko Zenmyo, Hidenori Kubo
1992 Volume 61 Issue 3 Pages
1025-1035
Published: March 15, 1992
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In proton NMR spectra of the title compound, the main and satellite lines are observed. The main line is due to the long range ordered moments of Co-type (
x<0.6) or Mn-type (
x>0.6) antiferromagnets. The satellite lines are intrinsic to the reentrant spin glass phase and are due to the moments in the spin glass state. The center frequencies strongly depend on the concentration and the line width has its maximum at about
x=0.75. We show that a random freezing of the longitudinal component of moments occurs in the spin glass state, as expected in Ising systems. However, the freezing of the moments is not completely random. The coupling of the freezing two moments depends on the probabilities which are determined by the concentration. The probabilities reflect only the sign of the exchange interaction.
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Shin-ichi Kuroda, Mitsuhiro Motokawa, Muneyuki Date
1992 Volume 61 Issue 3 Pages
1036-1048
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Submillimeter ESR of (NH
4)
2CuCl
4·2H
2O (Cl-salt), (NH
4)
2CuBr
4·2H
2O (Br-salt), CuCl
2·2H
2O and Cu(NH
3)
4SO
4·2H
2O (CTS) has been measured down to liquid helium temperature region by the apparatus using 337 μm wave of HCN laser and pulsed high magnetic fields up to 500 kOe. Each salt contains exchange-coupled inequivalent spin sites and so-called exchange splitting has been observed at room temperature. At liquid helium temperatures intensities of the two split lines are quite different and weaker line has shown a remarkable shift in Cl-salt, CuCl
2·2H
2O and CTS. In Br-salt only single line has been observed. These phenomena can be successfully explained by the molecular field theory. Inequivalent spins in CTS have been deduced by the theory to be anitiferromagnetically coupled while the coupling in Cl-, Br-salts and CuCl
2·2H
2O are ferromagnetic.
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Ashok Sharma, D. R. Sharma
1992 Volume 61 Issue 3 Pages
1049-1053
Published: March 15, 1992
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Using standard microwave techniques, the dielectric constant ε′ and dielectric loss ε″ for dilute solutions of Dimethylsulphoxide (DMSO) in benzene and carbontetrachloride (CCl
4) have been measured at 9.174 GHz at different temperatures (25, 30, 35 and 40°C). Following the single frequency concentration variational method suggested by Gopalakrishana, the dielectric relaxation time τ and dipole moment μ at various temperatures have been calculated. Based on above studies, monomer structure for DMSO in both the solutions have been inferred. The presence of solute-solvent association in both the solutions have been proposed. Dielectric relaxation process can be treated as the rate process just like the viscous flow process. Energy parameters for the dielectric relaxation process have been calculated and compared with the corresponding energy parameters for the viscous flow.
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Takehiko Hidaka
1992 Volume 61 Issue 3 Pages
1054-1062
Published: March 15, 1992
Released on J-STAGE: June 01, 2007
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The phenomenon of the overdamping of the soft phonons in several perovskite-structure crystals such as BaTiO
3 is discussed in relation to the potential parameters for the microscopic order parameter. The lower potential barrier (which is due to the large 6-th-order potential term) for a microscopic order parameter gives much higher hopping rate of order parameter. The rapid hopping of the order parameter gives the Debye-relaxation type profile in optical (and neutron) scattering spectrum, masking the spectrum from a resonance-type soft phonon. Also, the relationship between the overdamped soft phonon and successive transitions observed such as in BaTiO
3 is given.
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Chieko Totsuji, Takeo Matsubara
1992 Volume 61 Issue 3 Pages
1063-1068
Published: March 15, 1992
Released on J-STAGE: June 01, 2007
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In some perovskite oxides, addition of a small amount of other perovskite oxide induces a strong reduction of ferroelectric phase transition temperature. We apply the vibronically coupled two-band model to these mixtures and show that the transition temperature lowering is caused by the band width broadening which surpasses the effect of the band gap narrowing.
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Hiroshi Miyazaki, Takeshi Watanabe, Masahiro Inoue
1992 Volume 61 Issue 3 Pages
1069-1083
Published: March 15, 1992
Released on J-STAGE: June 01, 2007
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Optical properties are studied of an inflation lattice generated by the inflation rule α→{α
1α
2…α
n} and β→{β
1β
2…β
m}. A matrix recurrence equation is derived for the optical structure factors which is useful in the numerical calculation. Based on the multi-product representation, an analysis is presented of the fractal structure of the spectrum. The assumption of successive enhancement yields an analytic expression of the peak frequencies. The new labeling scheme of the peak frequencies enables us to describe the fractal structure of the spectrum in terms of the self-similarity factor σ.
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Kazutoshi Fukui
1992 Volume 61 Issue 3 Pages
1084-1097
Published: March 15, 1992
Released on J-STAGE: May 29, 2007
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Photoemission spectra of PbTe, SnTe and GeTe in polycrystalline (
c-) and amorphous (
a-) phases have been measured with excitation photon energies between 16 and 80 eV. Three peaks in the valence band spectra are attributed to bonding
p, cation
s and Te
s states. Widths of bonding
p states suggest that the covalency is stronger in the order of PbTe<SnTe<GeTe in
c-phase and in the order of SnTe<GeTe in
a-phase, and the covalency is stronger in
a-phase than in
c-phase in the same material. From the spectral shape of constant-initial-state spectra of each initial state in the valence band, it is derived that excited states from the cation outermost
d levels are localized but those from, Te 4
d levels are not in
c-IVTe′
s, while
vice versa in
a-GeTe. This also indicates that the covalency is stronger in
a-phase than in
c-phase.
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Tetsusuke Hayashi, Toshihiro Yanase, Tamao Matsumoto, Ken-ichi Kan&rsq ...
1992 Volume 61 Issue 3 Pages
1098-1112
Published: March 15, 1992
Released on J-STAGE: June 01, 2007
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Emission spectra and decay characteristics of luminescence in KBr
1−xI
x and RbBr
1−xI
x solid solutions have been investigated in the whole range of composition
x. The emission band due to localized excitons at I
− dimer centers in bromides, which consists of singlet and triplet components, is found to connect continuously with intrinsic σ band in pure iodides. The triplet component of the band is transformed into another emission with larger Stokes-shift in the intermediate region of
x. Time-resolved studies on this emission in KBr
1−xI
x have clarified that it consists of two triplet emission bands differing by ∼0.2 eV in their peak energies. The lower energy one corresponds to π band in KI. We demonstrate that the relaxed exciton configurations of different types are selectively realized depending on the local environment surrounding the I
2− molecular core of the exciton. Discussion is given on the dynamical relaxation process of free excitons in iodides.
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Haruichi Kanaya, Kazuhiro Hara, Hirotaka Okabe, Kazumi Matsushige, So ...
1992 Volume 61 Issue 3 Pages
1113-1118
Published: March 15, 1992
Released on J-STAGE: May 29, 2007
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The heat-induced gelation process of muscle protein, actomyosin, was investigated by observing the transmitted light spectra. First, the temperature characteristic of the gelation (
Tg′) was determined from the spectral changes, showing remarkable dependence on pH and [NaCl]. Moreover, the spectra varied drastically with time after the temperature-jump procedure. From the time dependence of the observed spectra, the turbidity was calculated to characterize the light-scattering properties. The logarithm of the turbidity showed approximately linear dependence on the logarithm of the wavelength, and the slope increased with time, suggesting the growth of the actomyosin assembly during the gelation process.
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Susumu Takeda, Masanori Hara
1992 Volume 61 Issue 3 Pages
1119-1120
Published: March 15, 1992
Released on J-STAGE: May 29, 2007
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