Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 63, Issue 2
Displaying 1-50 of 56 articles from this issue
  • Kimiaki Konno, Hitoshi Oono
    Subject area: Mathematical methods in physics.
    1994 Volume 63 Issue 2 Pages 377-378
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    New coupled integrable dispersionless equations are presented and solved by the inverse scattering method.
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  • Hiroyasu Yamada, Kazuhiro Nozaki
    Subject area: Classical and quantum physics: mechanics and fields.
    1994 Volume 63 Issue 2 Pages 379-382
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The motion of untwisted scroll rings in excitable media is investigated with an approximation analysis. Application of the multiscale expansion technique yields slow dynamics of scroll rings without a quasi-stationarity assumption. Our formulation gives not only the shrinking rate and drifting speed of scroll rings but also new results such as a frequency shift of rotation and a slow deformation of the meridian spiral.
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  • Zi–Song Hu, Kengo Takahashi, Yoshimi Tsuchiya
    Subject area: Mechanics, elasticity, and rheology.
    1994 Volume 63 Issue 2 Pages 383-387
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Transient behaviors in self-sustained oscillation of a plasmodial strand of Physarum polycephalum have been investigated for various external loads under isotonic conditions. Synchronization between divisions of the strand has been observed in its formation process, which shows that the plasmodial strand can be considered as a one-dimensionally coupled oscillator system. The synchronization has been found to proceed faster with increasing external load applied to the strand. It has furthermore been found that the rate of increase of the amplitude of oscillation increases with the load, whereas the temporal behavior of its period is independent of the load. These results show that the oscillators themselves in the plasmodial strand do not depend on the external load, but the coupling between these oscillators is strongly affected with the external load. The experimental results have also been simulated on the basis of one-dimensionally coupled van der Pol equations.
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  • Takashi Ishihara, Yukio Kaneda
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 2 Pages 388-392
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The three-dimensional motion of a flat uniform vortex sheet slightly perturbed initially in both streamwise and spanwise directions is studied on the basis of a Lagrangian representation of the motion. The vortex sheet at time t is represented as R(λ 1, λ 2, t)=(λ 1, λ 2, 0)+∑ n, mAn, m(t), exp, i(nλ 1+mδ λ 2), where λ 1 and λ 2 are Lagrangian parameters in the streamwise and spanwise directions, respectively, and δ is the aspect ratio of the periodic domain of the disturbance. The behaviour of An, 0 and An, 1 is studied by an asymptotic analysis valid at large t. The analysis shows that singularity appears on the sheet at a critical time O(ln, (ε 1-1)), where ε 1 is the initial amplitude of the streamwise disturbance. The singularity is such that An, 0 behaves like n-5/2 while An, 1 behaves like n-3/2, for large n. The latter is associated with the vortex stretching intrinsic in three-dimensional dynamics of the sheet.
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  • Isao Katanuma, Yasuhito Kiwamoto, Leonid G. Bruskin, Kiyoshi Yatsu, Te ...
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 2 Pages 393-396
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The electrostatic potential profile around a magnetic mirror throat is studied. Bohm's criterion expresses the necessary condition for the formation of a stationary sheath in front of the absorbing wall. This condition, when applied to the mirror throat of a magnetic mirror, requires that the ion drift velocity flowing into the mirror throat from the confining region must exceed the ion sound velocity for the continuity of the potential. It is found, however, that the ionization around the mirror throat renders the potential continuous even with zero ion drift velocity.
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  • Tadao Kasuya
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 397-400
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The experimentally observed Hall mobility in SmB6 is temperature- and sample-quality-independent in the temperature range where the gap is well established, while the relaxation time observed in the optical measurement increases with decreasing temperature. This discrepancy was solved in our proposed model. It is shown that the Hall constant sees essentially a large Fermi surface for monovalent metal and, for a constant Hall mobility, τ should increase as T-0.5, in good agreement with the experimental result.
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  • Tetsuro Saso, Takumi Hayashi
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 401-404
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The magnetization curve of the infinite-dimensional Hubbard model is calculated by using the quantum Monte Carlo method. The calculated curve is essentially the same as that of the exact solution in one dimension and that of the Gutzwiller approximation, which suggests the same behavior in all the intermediate dimensions. Combined with the knowledge on the Anderson impurity, the change of the shape of the density of states of the Hubbard model under a magnetic field is discussed.
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  • Hideo Yoshioka
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 405-408
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Fluctuation of spin magnetic susceptibility √ ‹ δ χ 2S› in mesoscopic metals is discussed in comparison with that of orbital magnetic susceptibility √ ‹ δ χ 2L› }. It is found that a ratio √ {‹ δ χ 2S› /√ ‹ δ χ 2L› is independent of temperature and the boundary condition and has a magnitude of the order of (1/ε Fτ )2 which is much smaller than unity, ε F and τ being Fermi energy and the relaxation time of the elastic scattering, respectively. Scattering dependent on electron spin (e.g., spin-orbit interaction or scattering by impurity spin in the glass state) are shown to suppress √ ‹ δ χ 2S› far more strongly than √ ‹ δ χ 2L› . The results indicate that the anomalously large fluctuation of the magnetic susceptibility compared to the average, which is expected to be observed experimentally, results from the orbital motion.
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  • Akio Fukushima, Fumitoshi Iga, Isao H. Inoue, Keizo Murata, Yoshikazu ...
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 409-412
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    We report transport and magnetic properties for single-crystalline CaVO3, which are seriously affected by oxygen off-stoichiometry. The electrical resistivity of a stoichiometric sample is well fit by the relation ρ =ρ 0+AT2 in an extremely wide temperature range. Oxygen off-stoichiometry causes the systematic increment of both ρ 0 and A. Magnetoresistance data also change drastically due to the oxygen off-stoichiometry; the stoichiometric sample shows positive magnetoresistance with B2 dependence, while a sample with a small number of oxygen vacancies shows an unusual negative magnetoresistance. Magnetic susceptibility of the latter sample shows Curie-Weiss behavior, while that of the former one shows Pauli paramagnetic behavior.
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  • Naoto Nagaosa, Akira Furusaki
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 413-415
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The tunneling through a potential barrier in a Coulomb gas confined in a quantum wire is discussed. The tunneling conductance g(T) at temperature T is found to be [g(T)∝exp, \left[ln, \frac{vF}{WT}-\frac{2}{3r}, \left {\left(1+r, ln, \frac{vF}{WT}\ ight)3/2-1\ ight}\ ight], \ ]where W is the width of the wire, vF is the Fermi velocity, and r=(8/π 2)rs=4e2/π vFε 0 is the dimensionless mean separation between electrons.
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  • Fumitaka Matsubara, Katsunori Morishita, Sakari Inawashiro
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 416-419
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    We study a dilute system of the classical Heisenberg spins coupled via the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction just above its critical concentration of the ferromagnetic phase using a hybrid Monte-Carlo spin-dynamics method. We find for the first time in finite-range models that the system exhibits a reentrant phase transition from a ferromagnetic phase to a mixed phase of the ferromagnetism and the transverse spin glass.
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  • Makoto Kaburagi, Takashi Tonegawa
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 420-424
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Low-lying excited states as well as the ground state of the spin-1 antiferromagnetic Heisenberg chain with a spin-1/2 impurity are investigated by means of a variational method and a method of numerical diagonalization. It is shown that 1) the impurity spin brings about massive modes in the Haldane gap; 2) when impurity-host coupling is sufficiently weak, the phenomenological Hamiltonian used by Hagiwara et al. (Phys. Rev. Lett. 65 (1990) 3181) in the analysis of ESR experimental results for Ni(C2H8N2)2NO2(ClO4) containing a small amount of spin-1/2 Cu2+ impurities is derived from a more realistic Hamiltonian, as far as the energies of the low-lying states are concerned; 3) the results obtained by the variational method are in semiquantitative agreement with those obtained by numerical diagonalization.
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  • Masafumi Tamura, Hiroshi Sawa, Yoshiaki Kashimura, Shuji Aonuma, Reizo ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 425-428
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Weak ferromagnetism has been found in (DBr-DCNQI)2Cu below the Néel temperature, TN=16, K. The remanent magnetization does not decrease with lowering temperature, which is in contrast to that observed for (DMe-DCNQI-d8)2Cu. The results suggest that the weak ferromagnetism is a universal feature of the antiferromagnetically ordered state of the DCNQI2Cu system.
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  • Masafumi Tamura, Hiroshi Sawa, Shuji Aonuma, Reizo Kato, Minoru Kinosh ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 429-432
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Temperature dependence of magnetic susceptibility of Cu salt of DMe-DCNQI-α, α '-d2 has been investigated over the temperature range of the metal-insulator-metal (M-I-M) reentrant transition. The insulating phase of this salt has been revealed to exhibit the same temperature dependence of susceptibility as that of the insulator phase of (DMe-DCNQI-d8)2Cu, which shows only a M-I transition. In the reentrant metallic phase, there is no sizable enhancement of susceptibility such as expected from the specific heat enhancement.
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  • Koichi Nakamura, Yoshio Kitaoka, Kunisuke Asayama, Toshiro Takabatake, ...
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 2 Pages 433-436
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Low-energy excitation in Kondo semiconductors CeNiSn and CeRhSb, has been investigated by the measurement of 119Sn and 123Sb nuclear spin-lattice relaxation rate, 1/T1. From a T3-like temperature dependence of 1/T1 for both compounds, it has been intuitively concluded that the pseudo energy gap with the V-shaped structure is formed in the effective density of states for heavy quasi-particles. The band width of D=210, K and the pseudo energy gap of Δ=28, K in CeRhSb are almost two times larger than those of CeNiSn (D=140, K and Δ=14, K), respectively. Below 0.4, K and 0.8, K for CeNiSn and CeRhSb, respectively, the T1T=const. behavior has been commonly observed in the two compounds, indicative of the presence of a residual density of states at the Fermi level. Impurities and/or imperfection in the samples easily mask the intrinsic V-shaped structure of the energy gap at very low temperatures.
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  • Fuminao Shimizu, Takayuki Anzai, Hiroshi Sekiguchi, Masaaki Takashige, ...
    Subject area: Dielectric properties and materials.
    1994 Volume 63 Issue 2 Pages 437-440
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Single crystals of K2ZnI4 with monoclinic Sr2GeS4 structure prepared by theBridgman method were investigated through DTA and dielectric measurements. Ferroelectric activity was found below 270, K, where the b-direction dielectric constant showed a sharp peak. The spontaneous polarization measured by the pyroelectric charge method was 0.32, μ C/cm2 at 100, K. The dielectric constant also showed a small stepwise anomaly around 190, K.
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  • Masaru Kasahara, Pho Kaung, Toshirou Yagi
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1994 Volume 63 Issue 2 Pages 441-444
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The linewidth of the internal mode ν 2 of SO42- ion of the antiferroelectric K3D(SO4)2 shows the anomalous broadening with lowering temperature near the phase transition point. The broadening is well explained by a mechanism resembling the motional narrowing phenomenon in the nuclear magnetic resonance theory. The characteristic time of the motion of deuteron in a hydrogen bond is estimated to be on the order of 10-13, s.
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  • Takao Yoshinaga, Tsunehiko Kakutani
    Subject area: Mathematical methods in physics.
    1994 Volume 63 Issue 2 Pages 445-459
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    In order to examine solitary and E-shock waves in a resonant system between long and short waves, a reduced set of ordinary differential equations (ODEs) are considered by a simple traveling-wave transformation. It is then shown that analytical solutions can be obtained systematically by means of the modified Hirota's method. A variety of numerical solutions including oscillatory solitary and E-shock waves are also found for various values of the parameters. In particular, characteristic properties of the solutions are examined for the case when the ODEs hold the Painlevé property. In this connection, integrability of the original partial differential equations (PDEs) in the nearly integrable region is discussed together with the Lyapunov exponent for the soliton-like solutions.
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  • E. V. Krishnan
    Subject area: Mathematical methods in physics.
    1994 Volume 63 Issue 2 Pages 460-465
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Travelling wave solutions for two nonlinear diffusion equations have been found by a direct method. A new equilibrium solution has been found for the diffusion equation ut=(u2)xx+u(u-1)(α-u) and also a singular solution when α=0 in the equilibrium state using the properties of elliptic functions.
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  • Fei Zhang, Yuri S. Kivshar, Luis Vázquez
    Subject area: Mathematical methods in physics.
    1994 Volume 63 Issue 2 Pages 466-471
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Sotiton-impurity interactions in the systems where the topological solitons (kinks) possess internal oscillatory modes are studied analytically and numerically. Taking the well-known φ4 model as a particular but rather general example, we demonstrate that the kink can resonantly pass two (or more) localized impurities due to excitation and deexcitation of its internal mode.
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  • H. Khushnood, A. R. Ansari
    Subject area: Specific reactions and phenomenology.
    1994 Volume 63 Issue 2 Pages 472-477
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The characteristics of short-short and short-long rapidity gap correlations in 50GeV π --nucleus and 400, GeV proton-nucleus interactions have been investigated. Thedependence of the characteristics of clusters on the multiplicity of grey particles, Ng, has also been studied. The results reveal that the behaviour of the rapidity gap correlations and the average cluster size are not only independent of the size of the target nucleus but also do not depend on the identity and energy of the impinging hadron. However, the increasing value of the parameter R with increasing value of Ng and the energy of the projectile indicates the dominance of the short-short rapidity gap correlations over the short-long correlations.
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  • Katsufusa Shoda, Osamu Sasaki, Kunikazu Takeshita, Tsutomu Taniuchi, H ...
    Subject area: Nuclear reactions and scattering: specific reactions.
    1994 Volume 63 Issue 2 Pages 478-484
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Energy distributions of π + electroproduced on 6Li, 9Be and 28Si were measured at the electron energy of about 200, MeV. The photon difference method was applied to these (e, , π +) spectra in order to extract the (γ, , π +) cross sections. Present results and previously obtained data show considerable contribution from several discrete levels of the residual nuclei. The spin-isospin flip giant resonance in residual nuclei could be studied up to about 20, MeV residual excitation except in 6Li which showed a small quasi-free and/or continuum contribution. In 9Be and 28Si, the present results show giant resonances in the residual nuclei with a width of about 15, MeV in the gross shape.
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  • Hiroshi Tanaka, Ludwig Boesten, Kunizo Onda, Osamu Ohashi
    Subject area: Atomic and molecular collision processes and interactions.
    1994 Volume 63 Issue 2 Pages 485-492
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Elastic electron scattering spectra of C60 in the vapor phase were recorded from 1 to 11.5, eV and scattering angles from 30° to 90°. Electron energy loss spectra are given for a loss from 1 to 55, eV at impact energies of 50 and 100, eV (5°). They confirm the known optically allowed transitions and resolve the ≈ 6, eV π -electron plasmon-peak at least into four steps at 5.8, 6.1, 6.3, and 6.5, eV. A small peak of width 2, eV has been found at 28.3, eV, the position of the “σ +π -plasmon” in solid films. Vibrational excitations were recorded at 7, eV for angles from 20° to 60° with a resolution of 34, meV and show two peaks at 0.06 to 0.11, eV and at 0.15 to 0.20, eV both of which contain optically forbidden transitions. The elastic DCS at 7, eV and a scattering angle of 30° is estimated to be of order 5× 10-14, cm2/sr.
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  • Kazuo Sasaki, Ryou Ohya
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 2 Pages 493-499
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Solitary-wave solutions are obtained numerically for the nonlinear Schrödinger equation with some additional terms, which describes the forced oscillation of certain surface waves on a fluid in a channel that is driven sinusoidally with time in a horizontal direction. The conditions on the drive amplitude and frequency necessary for the existence of solitary waves are determined.
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  • Noboru Takimoto, Shinzi Yamamura, Kunio Funayama
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 2 Pages 500-509
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    A discussion is given on a 1/f filter, which outputs a 1/f noise as a response to the white noise. It is shown theoretically and experimentally that, under proper conditions, an incompressible viscous fluid serves as the 1/f filter. Stimulated by the previous finding due to Mandelbrot et al. that the earth's pole motion involves the 1/f noise, a spherical shell enclosing a fluid is set in rotation about its diameter by a fluctuating external torque with the white spectrum, and its angular velocity is measured. It is found that, under the conditions predicted by the theory, the angular velocity involves the 1/f noise.
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  • Akio Fukuyu, Taxpolat Ruzi, Akimitsu Kanai
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 2 Pages 510-527
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The response of Hill's vortex to a small three dimensional disturbance is examined. The perturbed field is expanded by the spherical solid harmonics Ynm and a system of equations for the evolution of the expansion coefficients is obtained. It is shown that these equations are closed for each azimuthal number m. In a case of axisymmetric distortion, Moffatt and Moore (1978) showed that if the initial disturbance is such as to make the vortex prolate spheroidal, rotational fluid is detrained, forming a thin spike at the rear stagnation point, and if the vortex is initially oblate, irrotaional fluid is entrained there. When the initial distortion is not axisymmetric, numerical results for m=2 show that a peak of initial surface elevation moves downstream toward the rear stagnation point forming a spike-like structure.
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  • Jun Sang Park, Jae Min Hyun
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 2 Pages 528-535
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Time-dependent motions of a compressible fluid in response to an abrupt rotation of the cylindrical container are considered. Concern is directed to the case of a rapidly-rotating cylinder; the reference Ekman number, E, is very small and the peripheral Mach number M≈ O(1). Numerical solutions to the complete Navier-Stokes equations are secured to appraise the relative importance of the major dynamical ingredients in the flow process. These endeavors are complementary to earlier works which demonstrated the global evolution of the dominant velocity component. The magnitudes of the terms of the azimuthal momentum equation are evaluated to enable specific comparisons of the dynamics effects involved. At high Mach numbers, the oscillatory behavior of the main flow is shown to be attributable to thermo-acoustic modes. The radial density stratification is strengthened as the Mach number increases; because of this, the fluid in larger portions of the cylinder interior experiences rarefaction and cooling. The consequence turns up in the form of retardation of the overall spin-up process as M increases.
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  • Nobuaki Ikuta, Hiroaki Gotoda, Ryuichi Yokoyama
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1994 Volume 63 Issue 2 Pages 536-545
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Electron velocity distribution and transport properties under an electric field have been analysed by the Boltzmann equation giving the flow-in rate with a scalar number of the momentum transfer collision frequency ν m(v). This is equivalent to treat electrons as if they are isotropically scattered with ν m(v) in spite of the fact being anisotropically scattered. Maintaining the momentum transfer cross section constant with the change of anisotropy in the elastic scattering, the validity of such pseudo-isotropic analyses has been examined by the extended FTI method assuming a simple model anisotropy. The results show that the transverse diffusion coefficient take erroneous values in the usual pseudo-isotropic analyses so far conveniently used.
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  • Yoshiomi Kondoh, Yasuo Hosaka, Jia–Ling Liang, Ritoku Horiuchi, ...
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1994 Volume 63 Issue 2 Pages 546-557
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Functional dependence of relaxed states of magnetohydrodynamic (MHD) plasmas on profiles of resistivity η is derived approximately as μ 0j//~= √ μ 0α /2η B for parallel components to B, by using a general self-organization theory based on dissipative structures due to selective dissipations associated with higher eigenmodes for dissipative dynamic operators. Typical results of three-dimensional simulations for resistive MHD plasmas with both “nonuniform η ” and “uniform η ” are shown to compare with the theoretical result. Comparison between the theoretical and the numerical results suggests that the attractor of dissipative structures in resistive MHD plasmas is given by \ abla× (η j)=(α /2)B and is reduced to \ abla× B=λ B in the case with the “uniform η ” and no pressure gradient.
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  • Yoshinori Tatematsu, Yasuhito Kiwamoto, Teruo Saito, Teruo Tamano
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 2 Pages 558-572
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Theoretical analyses are made on the structure of the potential distribution along open field lines in a plasma where the velocity distributions of particles are modified from Maxwellian to include Yushmanov-trapped components and temperature anisotropy. The considered particle species are warm electrons and ions flowing out of the system, secondary electrons flowing backward, and Yushmanov electrons trapped between a stronger side of the magnetic field and reflecting potential. The analyses show systematic variations in the potential profile with the change in the temperature anisotropy and the abundance of the Yushmanov-trapped particles. Moreover, the analyses predict measurable feed-back effects to the local heating for the plasma control.
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  • Mieko Toida, Yukiharu Ohsawa
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 2 Pages 573-582
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Investigations are made of nonlinear magnetosonic waves propagating perpendicular to a magnetic field in a multi-ion plasma. The magnetosonic wave is split into two modes in a two-ion plasma; low- and high-frequency modes. The frequency of the low-frequency mode tends to zero as the wave number k goes to zero. A KdV equation is derived for this mode by the conventional reductive perturbation method. The frequency of the high-frequency mode does not tend to zero as k→ 0. Using a new expansion scheme in which the amplitude ε is assumed to be much larger than (me/mi)1/2, where me/mi is a measure of electron-to-ion mass ratios, it is found that the nonlinear high-frequency mode can also be described by a KdV equation, although it has a finite cut-off frequency. This shows that KdV equations are not limited to the waves whose frequencies tend to zero as k→ 0.
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  • Haruhiko Takase
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 2 Pages 583-592
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The (1+2) dimensional (1-D in real space and 2-D in momentum space) relativistic Fokker-Planck code combined with the ray-tracing code has been newly developed for analyzing the lower hybrid current drive (LHCD) on tokamak plasmas. This numerical code calculates the 2-D MHD equilibrium, ray-tracing, and Fokker-Planck analyses self-consistently. The simulations have been carried out by using the code, and the results were compared with experiments on the lower hybrid current drive in JT-60. As a result, the obtained simulation results agreed with the experimental results on the current drive efficiency and the current density profile ( or the plasma internal inductance).
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  • Shoji Hirokawa, Tomoko Imasaka, Takasuke Matsuo
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1994 Volume 63 Issue 2 Pages 593-601
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    A system of planar rotators representing H2S and D2S molecules is investigated quantum-statistically, using the mean-field approximation based on an eight-sublattice model. The equilibrium molecular orientation is determined by competition among the dipole-dipole interaction between guest molecules, the host-guest interaction and the quantum kinetic energy. The system has a complex order parameter describing an average direction of dipoles. Both R1 and R3 structures and the effect of the depolarization field are studied. A comparison with experiment by use of theoretical phase diagrams gives: the low-temperature phase has the R1 structure with an antiferroelectric order of dipoles; the direction and arrangement of dipoles in equilibrium for H2S significantly differ from those for D2S because of the quantum nature of the rotational motion.
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  • Fusayoshi J. Ohkawa, Naoyuki Matsumoto
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 602-614
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The origin of the superexchange interaction is reexamined in order to clarify that it works even in metallic phases. The wellknown kinetic exchange process is nothing but the virtual exchange process of high-energy spin excitations between the lower and upper Hubbard bands. The mechanism for Cooper pairing between Gutzwiller's heavy electrons, whose band lies between the lower and upper Hubbard bands, by the superexchange interaction can be regarded as that by high-energy spin fluctuations. Because it can also be regarded as a kind of an excitonic mechanism using high-energy spin excitations, it is plausible that the superexchange interaction causes high-temperature superconductivity of Gutzwiller's heavy-electron liquids.
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  • Masafumi Tamura, Haruo Kuroda, Shinya Uji, Haruyoshi Aoki, Madoka Toku ...
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 615-622
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Analysis of the temperature and field dependence of the de Haas-van Alphen oscillations in an organic superconductor θ -(BEDT-TTF)2I3 is presented. The cyclotron masses are estimated to be 2.0me and 3.6me for slow and fast oscillations, respectively. The indication of magnetic breakdown effect is discussed in terms of the geometry of the Fermi surface. The result is compared with those of the infrared reflectance spectra and the empirical tight-binding band calculations.
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  • Shintaro Nakamura, Terutaka Goto, Satoru Kunii, Katsuhiko Iwashita, Ak ...
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 623-636
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Temperature dependence of the elastic constants in a series of rare earth hexaborides has been investigated by means of the ultrasonic method. The remarkable softening of the transverse C44 mode in PrB6, NdB6, DyB6 and HoB6 has been discussed in connection with the cooperative Jahn-Teller effect due to the CEF ground state degenerated by the quadrupolar moment. The low temperature behavior of C44 in CexLa1-xB6 compounds is presented to show the Kondo effect on the quadrupolar moment of Γ8 ground state. The anomaly of the bulk modulus CB in SmB6 is related to the valence fluctuation state in the system.
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  • Hitoshi Sumi, Atsuko Sumi
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 2 Pages 637-657
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Self-trapping (ST) of excitons (or electrons) interacting with phonons via short-range potentials depends strongly on the degree of freedom of their motion on the lattice. When excitons can move three-dimensionally, the self-trapped (S) state appears suddenly as a strongly-localized one when the coupling constant (g) exceeds a certain critical value. Free (F) states do not become unstable however large g is. When exciton motion is limited only in one dimension, excitons are always self-trapped and F states are unstable irrespective of the magnitude of g (≠ 0). The S state appears as a strongly-extended one in the limit of g→ 0, and its spatial extension decreases as g increases. For excitons mobile in two dimensions, there exist two critical values gc1 and gc2 (>gc1) of g: The S state appears suddenly as a strongly-localized one when g exceeds gc1, but F states become unstable when g exceeds gc2 although they are metastable for gc1c2.
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  • Taichi Terashima, Norimichi Kojima
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 658-673
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Incommensurate layer compounds (RES)xNbS2 are a new class of the intercalation compounds of NbS2; the x=1.2 and the x=0.6 compound have a stage-1 and a stage-2 structure, respectively. The results of the resistivity and the Seebeck coefficient measurements for several of them and the Pauli paramagnetic susceptibility of (LaS)1.2NbS2 are well interpreted with the rigid-band model by incorporating a large charge transfer from the intercalate RES layer to the host NbS2 layer. Large residual resistivities of the compounds are discussed in terms of the structural incommensurability. A logarithmic temperature dependence of the resistivity observed for the stage-2 compounds below -- 20, K is discussed in relation with the carrier localization. A fractional superconductivity has been observed for most of the samples below 2-- 6, K and its model based on the peculiar structure is proposed.
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  • Yasuhiro Iye, Ryuta Yagi, Noriaki Hanasaki, Seiichi Kagoshima, Hatsumi ...
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 674-684
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Angular dependent magnetoresistance oscillation (ADMRO) effect in α -(BEDT-TTF)2MHg(SCN)4 [M: K, , NH4] has been studied as a function of the polar and azimuthal angles of applied magnetic field with respect to the most conducting ac-plane. The ADMRO effects in these two structurally similar compounds are drastically different in their azimuthal angle dependence and oscillation waveform. While the ADMRO in NH4Hg-salt is of the standard type arising from a warped cylindrical Fermi surface, that in KHg-salt is a novel type to be attributed to an open Fermi sheet. Calculation based on a model recently proposed for a quasi one-dimensional system quantitatively reproduces the essential features of the anomalous ADMRO in KHg-salt.
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  • Tomi Ohtsuki, Yoshiyuki Ono, Bernhard Kramer
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 2 Pages 685-694
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The localization problem in a three dimensional tight binding system in the presence of a spatially random vector potential is investigated. The density of states exhibits tails of localized states that are induced by large regions in space where the vector potential is accidentally constant. In the center of the band the states are shown to be extended by investigating the system size dependence of the inverse participation number. The existence of a metal-insulator transition at a critical energy with non-vanishing density of states is demonstrated. The system size and energy dependent exponential decay length of the modulus of the Green's function satisfies a one-parameter scaling law. The value of the critical exponent is estimated, ν ≈ 1, which is different from those found previously for the disordered tight binding (Anderson) model with and without homogeneous magnetic field.
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  • Hijiri Kito, Jun Akimitsu, Fujio Izumi, Takashi Kamiyama, Hajime Asano
    Subject area: Superconductivity.
    1994 Volume 63 Issue 2 Pages 695-699
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The structure parameters of (La1-xCax)2CuO4 (x=0.05) with the K2NiF4-type structure were refined by Rietveld analysis of time-of-flight neutron powder diffraction data. This superconductor with a Tc of 24, K is orthorhombic at both room temperature and 18, K. From experimental results obtained by us and Fukuoka et al., we conclude that the relatively low Tc value for the superconductor is due to a low concentration of hole carriers introduced by Ca doping.
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  • Shigeki Ohsugi, Yoshio Kitaoka, Kenji Ishida, Guo–qing Zheng, Ku ...
    Subject area: Superconductivity.
    1994 Volume 63 Issue 2 Pages 700-715
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Results of extensive Cu NMR and NQR studies in the superconducting La2-xSrxCuO4 with x=0.075-- 0.24 have been presented. The rapid decrease of the nuclear spin-lattice relaxation rate, 1/T1, and the spin Knight shift below Tc confirm microscopically the existence of the superconducting phase with lower Tc than 38, K for 0.10 ≤ x ≤ 0.24. For x=0.10, magnetic anomalies emerge at low-T in some small parts of the sample, e.g. T-independent T1 and broadening of spectrum, having some relevance to the magnetic order in La2-xBaxCuO4 with x=0.125. For x>0.15, the T1T=const. behavior and the existence of the residual spin Knight shift far below Tc have revealed that the superconductivity is of a gapless type with a finite density of states at the Fermi level caused by the mixture of different structures, i.e. tetragonal and orthorhombic.
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  • Shuzo Kawarazaki, Yutaka Kobashi, Toshifumi Taniguchi, Yoshihito Miyak ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 716-725
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    We have carried out neutron diffraction experiments in order to study on the intermediate phase of the mixed system, U(Ru1-xRhx)2Si2, of URu2Si2 and URh2Si2, which are a heavy Fermion and a localized f-electron compounds, respectively. In the intermediate phase, the magnetic moment of the uranium atom has a normal magnitude but the ground state has a complex multi-Q-domain structure. The origin of this state is discussed on the basis of competing anisotropic interactions and randomness in them. An energy-based consideration is given to understand the variation of the magnetic structures in U(Ru1-xRhx)2Si2 and Ce(Ru1-xRhx)2Si2 sytems.
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  • Hiroyuki Kita, Andreas Dönni, Yasuo Endoh, Kazuhisa Kakurai, Nori ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 726-735
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The magnetic phase diagram of the heavy fermion superconductor UPd2Al3 (TN=14.3, K) has been determined in magnetic fields up to 5, Tesla by single crystal neutron diffraction experiments, which were performed at several temperatures above and below the superconducting transition at Tc=1.8, K. Observed magnetic intensities correspond to the magnetic structure with a field-independent magnetic propagation vector k=[0, , 0, , 1/2]. A magnetic field applied in the hexagonal a-b plane gives rise to domain reorientations, in addition rotates the direction of the ordered magnetic moments against a small anisotropy in the easy a-b plane, and makes the moment directions perpendicular to the field direction. This model allows a quantitative analysis of the observed field dependence of magnetic peak intensities. No superconductivity-induced changes of the antiferromagnetic order in UPd2Al3 are observed in our experiments. However, an anomaly detected in the temperature dependence of the zero-field sublattice magnetization for 11, K≤ T ≤ 14.3, K indicates a change in the magnetic structure of UPd2Al3.
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  • Hiroshi Amitsuka, Toshiro Sakakibara
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 736-747
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Specific heat C, electrical resistivity ρ, magnetization M and magnetic susceptibility χ have been measured for the dilute tetragonal heavy-electron compounds UxTh1-xRu2Si2 (x≤ 0.07), in the temperature range 100, mK≤ T≤ 360, K and in the magnetic fields H up to 55, kOe. Non-Fermi-liquid behavior with unusual lnT dependence of C, ρ and χ has been observed at the low temperatures: as the temperature is lowered below about 10, K, C/T and χ increase logarithmically, and ρ decreases logarithmically. Systematical variations of these quantities with uranium concentration indicate that the observed non-Fermi-liquid behavior is ascribed to the properties of a single U ion embedded in the Th site of the ThRu2Si2 metal. The magnetization curves M vs H/T indicate a strong uniaxial magnetic anisotropy along the tetragonal c-axis as well as a strong reduction of the 5f moment of U ions. A possible interpretation based on the recent developments of the S=1/2 two-channel Kondo model is given.
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  • Akira Yazaki, Keisuke Tajima, Yoshiei Todate, Syoïchi Tomiyoshi, ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 748-754
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Neutron paramagnetic scattering experiments have been made on antiferromagnets of RbMnF3 and Mn3Pt by means of Time of Flight (TOF) technique. The constant q mode data have been constructed by selecting the data points of the same q value from a set of TOF spectra. A simple Lorentzian scattering function has been assumed for the analysis and characteristic properties of the paramagnetic spin dynamics have been compared between these Heisenberg and metallic antiferromagnets.
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  • Tôru Sakai, Minoru Takahashi
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 2 Pages 755-761
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    We study the spin-1 antiferromagnetic Heisenberg chain under the three boundary conditions, which are the free, periodic and antiperiodic boundary conditions, by numerical diagonalization up to 16 sites. We checked that the lowest excitation caused by the domain wall, which is imposed by the boundary condition and breaks the long-range string order, yields the same energy gap under all the boundary conditions in the infinite length limit. It is also found that the ground state and the first excited state have the same density (about 3%) of domain walls due to the quantum fluctuation which reduces the string order parameter about 10% smaller than that of the VBS model in the ground state. The analysis of the mean distance between two domain walls suggests that domain walls due to the quantum fluctuation form a bound state in pairs and does not break the long-range string order.
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  • Hideki Watanabe, Eiichi Hirota, Akira Okada, Kouichi Hamada, Iwao Ishi ...
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 2 Pages 762-768
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    Ferromagnetic resonance (FRM) measurements were made on [Ni0.8Fe0.15Co0.05/Cu/Co] multilayers in order to observe the coupling between ferromagnetic layers across Cu spacer. The resonant fields vary oscillatory with Cu spacer thickness. The FMR results were analyzed by the resonant model of a magnetically coupled two-layer system. By using a modified RKKY theory for interlayer exchange interaction and FMR results, the coupling constant, J, was determined as a function of Cu spacer thickness. The resonant field can be predicted for Cu spacer thickness and are well compared to the experimental values. In samples of antiferromagnetic coupling, the resonance mode of the magnetization flopping were observed at small applied fields.
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  • Isayuki Horio, Xue–Zhi Zhou, Allan Henrry Morrish
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 2 Pages 769-774
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    The surface magnetic structure of γ -56Fe2O3 acicular particles with and without adsorbed Co2+ ions was investigated by coating with 57Fe2+ ions and then employing Mössbauer spectroscopy. The samples were characterized by chemical analysis, transmission electron microscopy, X-ray diffraction and magnetic measurements. The Mössbauer spectra at room temperature consisted of a sextet with broad lines with tails towards zero velocity. At 4.2, K in an applied field of 50, kOe the spin structure is non-collinear especially for the samples with the adsorbed cobalt ions.
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  • Yutaka Nakai
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 2 Pages 775-780
    Published: February 01, 1994
    Released on J-STAGE: October 01, 1999
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    About 90% of Sn atoms in β -Mn structure are found by means of neutron diffraction to occupy site II and neither antiferromagnetic long range order nor remarkable short range order was observable. By Mössbauer spectroscopy of 119mSn, the magnitude of the electric field gradient (EFG) decreases with an increase in Sn concentration. The EFG distribution functions are expressed by the sum of two Lorentz distributions. From the stable distribution analysis of internal field distributions, it becomes clear that the magnetic moments randomly freeze in the noncollinear manner.
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