Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 64, Issue 6
Displaying 1-50 of 52 articles from this issue
  • Koji Hukushima, Koji Nemoto
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 6 Pages 1863-1865
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    We propose a new technique to evaluate the maximum eigenvalue of the Hermite matrix, λmax , and the exponent at the spectrum edge, α , by using the forced oscillator method. This method is applied to the interaction matrix of the three-dimensional ± J EA model and we obtain λmax=4.49± 0.01 and α =0.22± 0.02.
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  • Kazunori Sato, Norio Konno
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1866-1869
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    We study the successional models which include two phases in successional sequences, sun trees and shade trees, where replacement from the former to the latter occurs only between nearest-neighbor trees in the two-dimensional lattice space. Both the successional model (Durrett and Swindle, Durrett and Schinazi, and Durrett) and the epidemic model (Sato et al.) are special cases of our model. This model is analysed by Monte Carlo simulations with comparison between mean-field approximation and pair approximation which considers only nearest-neighbor interactions. The results show that the model parameter α, which represents the degree of transition from a vacant site to a shade tree, affects the steady state of the population.
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  • Shin Horikawa, Akio Nakahara, Tomoo Nakayama, Mitsugu Matsushita
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1870-1873
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Fourier analysis has been applied to density waves of granular material (sand) which flows through a pipe. We let sand flow from a hopper through a vertical glass pipe due to gravity. The flow appeared intermittent, reminiscent of a chain of traffic jams on a crowded highway, over the length of the pipe except for the uppermost part where the sand flowed smoothly and homogeneously from the hopper. The FFT power spectra were found to change from a rather structureless form to a stable power-law form of 1/fα with α ~= 1.5 as we varied the measuring position from the hopper down to the pipe end. This result shows the occurrence of self-organized critical density waves in granular material flow through a pipe.
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  • Kohtaro Orito, Masatomo Sato, Haruyuki Irie
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1995 Volume 64 Issue 6 Pages 1874-1876
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    It is well known that the nonlinear Rossby wave equation has a dipole vortex solution, the so-called modon, in the short-wavelength regime. For a steady state in the long-wavelength regime, we find an appropriate variable transformation to express the potential vorticity in conservation form, and obtain a nonlinear Schrödinger equation for the stream function. It is found by numerical analysis that the equation has a monopole vortex solution for small separatrix radius.
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  • Hiori Kino, Hidetoshi Fukuyama
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 6 Pages 1877-1880
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The nature of the metal-insulator (MI) transition of α -(ET)2I3 has been studied theoretically. The effect of the on-site Coulomb interaction has been investigated at absolute zero within the Hartree-Fock approximation. If the Coulomb interaction exceeds some critical value, charge transfer occurs between different stacks and antiferromagnetic spin ordering is stabilized one-dimensionally along one stack, which results in the MI transition. It is also argued that this MI transition will lead to spin-Peierls-like distortion making the ground state nonmagnetic. Hence the present theoretical results offer a possible explanation for the intriguing feature of the MI transition of the title material.
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  • Takeharu Okuno, Shinji Kawaji, Takahiro Ohrui, Tohru Okamoto, Yuka Kur ...
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 6 Pages 1881-1884
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Breakdown of the quantum Hall effect due to current has been measured in specially designed samples with width ranging from 3 to 60, μ m made from five different GaAs/AlGaAs heterostructure wafers at 0.5, K in magnetic fields B up to 6, T. Critical current at the onset of the breakdown is proportional to the sample width irrespective of electron mobility between 13.5 and 27, m2/Vs. The critical Hall electric field at the breakdown for quantized Hall plateaus with a given even plateau quantum number is proportional to B3/2 and does not depend on the electron mobility of the sample.
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  • Shinya Yamaguchi, Hirohisa Taniguchi, Hidenori Takagi, Takahisa Arima, ...
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 1885-1888
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Magnetotransport properties have been investigated for metallic crystals of La1-xSrxCoO3 (x=0.20 and 0.30) with perovskite structure. Around the ferromagnetic transition temperature (Tc), fairly large negative magnetoresistance (MR) has been found. The magnitude of the MR is proportional to square of the magnetization above Tc and appears to be enhanced as the metal-insulator compositional phase boundary is approached. The results are discussed in terms of the double exchange mechanism.
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  • Ryuji Abe, Masakiyo Horioka, Izumi Sakumiya, Takayoshi Horio
    Subject area: Dielectric properties and materials.
    1995 Volume 64 Issue 6 Pages 1889-1891
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Dielectric dispersion of supercooled diethyleneglycol has been measured in the frequency range from 0.1, kHz to 1, GHz. Universal scaling behavior and its breakdown at a certain critical temperature Ta are observed, which is similar to the results reported earlier for other supercooled systems. Significantly, the dielectric dispersion disappears completely above Ta and appears again below the melting point as already observed for trimethyleneglycol. This fact suggests that such peculiar behavior of dielectric dispersion occurs generally for molecules which have centersymmetric structures.
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  • Yutaka Mooritomo, Yoshinori Tokura, Tomoyuki Mochida, Akira Izuoka, Ta ...
    Subject area: Dielectric properties and materials.
    1995 Volume 64 Issue 6 Pages 1892-1895
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Dielectric properties have been investigated for proton-deuteron mixed crystals of 5-bromo-9-hydroxyphenalenone with strong intramolecular hydrogen bonds. The fully deuterated compound shows two successive structural transitions, { i.e.}, incommensurate (IC) transition (TIC -- 37, K) and lock-in transition (TC -- 20, K). With increasing proton concentration (x), both of the critical temperatures decrease and the transitions disappear at xIC -- 0.65 and xC -- 0.25, respectively. This observation suggests that intramolecular tunneling motion of the protons significantly influences the structural phase transitions via the molecular tautomerization process.
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  • Yuji Shimada, Akio Nakahara, Mitsugu Matsushita, Tohey Matsuyama
    Subject area: Biophysics.
    1995 Volume 64 Issue 6 Pages 1896-1899
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Spatiotemporal patterns formed by a bacterial colony of Proteus mirabilis on an agar plate were observed. About half or one hour after the colony spread over the entire surface of the agar medium in a petridish, various patterns including target and spiral patterns appeared. They are very similar to those seen in other dissipative systems, such as chemical oscillations and electrohydrodynamic convective systems. Microscopic observations revealed that the collective motion of bacterial cells is responsible for the formation of these spatiotemporal patterns.
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  • Tetsu Yajima
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 6 Pages 1901-1909
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Integrable equations derived from the derivative nonlinear Schrödinger equation by the gauge transformation are considered. The Lax pairs and the solutions of them are studied. In addition, a set of equations which have multiple components is proposed. Their solutions are expressed as products of localized functions which have different velocities, amplitudes and widths. They have time-depending internal structures and show non-symmetric envelopes.
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  • Masato Hisakado, Miki Wadati
    Subject area: Mathematical methods in physics.
    1995 Volume 64 Issue 6 Pages 1910-1916
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    We consider a nonlinear DNA model which has discontinuities of the mass distribution and spring constant distribution. Incident, reflected and transmitted waves are described by the nonlinear Schrödinger equations on different coordinates. Fission and reflection of a soliton due to the discontinuity are explicitly shown. Implications of the results to DNA dynamics are discussed.
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  • Sigeo Yomosa
    Subject area: Classical and quantum physics: mechanics and fields.
    1995 Volume 64 Issue 6 Pages 1917-1935
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Dynamical features of solitary excitations in DNA are studied under the assumption that the most relevant modes to lead a locally open state are nonlinear collective modes of base rotations. Some remarks and reconsiderations are given about the expression of the H-bonding potential between complementary bases. Extended Hamiltonian is formulated by introducing the coupling interactions between rotational motions and longitudinal and transverse vibrational motions into a plane base-rotator model. In the continuum limit the double sine-Gordon equations and the soliton solutions which can be attributed to the open state are obtained. The energy and the length of the open configuration theoretically estimated are in same order with the values inferred from H-D exchange measurements. Number of solitons in a DNA with length of 105 base pairs is estimated to be about 4 at physiological temperatures.
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  • Hidetoshi Konno, Peter S. Lomdahl
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1936-1944
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Classification of statistics for a generalized birth-death stochastic process is studied with the use of the system size expansion method. Clarified is the physical and mathematical nonlinear structure which gives sub-Poissonian statistics in nonequilibrium open systems. It is also shown that sub-Poissonian statistics is ubiquitous in nonequilibrium open systems.
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  • Takao Yamamoto
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1945-1954
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The vicinal surface is well described by the terrace-step-kink model below the faceting temperature. On the basis of this model, the statistical-mechanics of the surface is transformed to the one-dimensional free-fermion system. On the other hand, rough surfaces including the vicinal surface are also expressed by the capillary-wave model. The two pictures of the vicinal surface are quite different, but we successfully derive the capillary wave description with the ''correct stiffness tensor'' from the free-fermion description by the bosonization technique. We show that the low-energy fluctuation of the terrace-step-kink model can be expressed by the capillary-wave picture in the sense inclusive of the anisotropic properties.
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  • Hiroaki Nakamura, Naomichi Hatano, Minoru Takahashi
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1955-1966
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The finite-size scaling function of the magnetization of the ferromagnetic Heisenberg chain is argued to be universal with respect to the magnitude of the spin. The finite-size scaling function is given explicitly by an analytical calculation in the classical limit S=∞ . The universality is checked for S=1/2 and 1 by means of numerical calculations. Critical exponents are also obtained. It is concluded that this universal scaling function originates in the universal behavior of the correlation function.
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  • Yoshihiro Nishiyama, Naomichi Hatano, Masuo Suzuki
    Subject area: Statistical physics and thermodynamics.
    1995 Volume 64 Issue 6 Pages 1967-1979
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    A ground-state phase transition of the antiferromagnetic Heisenberg ladder model is investigated by means of the exact-diagonalization method. A hidden-order correlation is defined for characterizing the ground state. The critical point and the exponent ν are estimated accurately with the use of the hidden-order correlation. The relevance of the resonating-valence-bond theory to the present system is also discussed by inspecting hidden orders and the elementary excitation.
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  • Ho–Young Kwak, Hyup Yang
    Subject area: Acoustics.
    1995 Volume 64 Issue 6 Pages 1980-1992
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Sonoluminescence (SL), the phenomenon of light emission associated with the collapse of bubble oscillating under ultrasonic pressure field has been studied by solving the conservation equations for the gas inside bubble analytically. Heat transfer in the liquid layer adjacent to the bubble wall has also been considered in this analysis. It has been found that the gas behavior is neither adiabatic nor isothermal for a bubble under ultrasound conditions. In this analysis, the launch condition and the Hugoniot curve for the shock propagation have been identified, and the shock duration of 2.7 to 17, ps, which is comparable to experimental result, has been obtained with the use of a similarity solution for converging spherical shock. For SL, the gas temperature after the shock focusing has been found to be 7000, K-- 44000, K, depending on the equilibrium bubble radius and the driving amplitude of ultrasound. It has also been found that the heat flux at bubble collapse is as large as 47, GW/m2, which could be more than enough to cause an explosion of an explosive crystal.
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  • Osamu Sano, Kiyomi Kutsumi, Norio Watanabe
    Subject area: Fluid dynamics.
    1995 Volume 64 Issue 6 Pages 1993-1999
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    An experimental and theoretical study is made on the translational oscillation of a mercury drop in a horizontally placed petri dish filled with HNO3 solution, where solid state K2Cr2O7 is dissolved from a certain fixed position. The latter diffuses gradually into the former solution, so that almost steady spatial distribution of K2Cr2O7 with concentration c is achieved. When the mercury drop is exposed to the solution where both c and gradc are small, it is pulled toward a higher c region. On the other hand when it reaches a very high c region, it undergoes stronger chemical reaction accompanied by a cloud of precipitation and recedes toward lower c region. This process is repeated and the oscillatory motion is established. Hydrodynamical analysis taking account of the non-uniform distribution of surface tension associated with chemical reaction is given to explain this phenomenon.
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  • Akio Fukuyu
    Subject area: Fluid dynamics.
    1995 Volume 64 Issue 6 Pages 2000-2011
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    To find a possible dynamical mechanism to lead to finite time singularity formation in three dimensional inviscid flow, the interaction of two vortex filaments with different strength is examined. It is observed by the numerical simulations using the Biot-Savart's law that when a weak vortex filament approaches to a strong straight filament, weak one winds round to strong one while the latter stays almost straight if the difference of the strength of two filaments is large. Due to the induced velocity of weak wound filament the strong filament is stretched efficiently at the middle point of it. A simple model for the winding process is examined.
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  • N. Reggiani, P. H. Sakanaka
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1995 Volume 64 Issue 6 Pages 2012-2017
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The hamiltonian character of the perturbed magnetic field lines of a confined plasma let them be described by an area-preserving map. We use the fractal diagrams to analyse the destruction of the magnetic field lines of a Reversed Field configuration, when its magnetic configuration is described by a Generalized Standard Map. The fractal diagrams show that the dynamics of the magnetic surfaces is very dependent on the kind of magnetic perturbation, mainly on the number of modes of the perturbative spectrum.
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  • Reiji Sugaya, Hideyuki Tachibana, Hirobumi Yamashita, Kouji Miyake, Ak ...
    Subject area: The physics of plasmas and electric discharges.
    1995 Volume 64 Issue 6 Pages 2018-2035
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Experimental and theoretical studies of electron heating and energy transport due to nonlinear Landau damping of electrostatic waves in an electron beam-plasma system immersed in a magnetic field were performed. Electron heating occurs by quasi-linear electron Landau damping of Trivelpiece-Gould mode induced explosively by nonlinear Landau damping of the slow space charge wave of the electron beam. It is predicted theoretically that the electron heating is caused by the energy transfer from the electron beam, and that the small axial drift of plasma electrons is generated by the momentum transfer from the electron beam. The energy transport by this drift can be balanced with the diffusion and the heat conduction, and this can maitain the large axial inhomogeneity of the electron temperature and density.
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  • Mieko Toida, Yukiharu Ohsawa
    Subject area: The physics of plasmas and electric discharges.
    1995 Volume 64 Issue 6 Pages 2036-2046
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The ion dynamics in perpendicular nonlinear magnetosonic waves in a plasma containing two ion species is studied through theory and simulation using a one dimension, electromagnetic particle code with full ion and electron dynamics; in the simulations the density of heavier ions was set to be 10
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  • Takashi Fujikawa, Masaru Yimagawa, Takafumi Miyanaga
    Subject area: Structure of liquids and solids; crystallography.
    1995 Volume 64 Issue 6 Pages 2047-2068
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    In this work we have developed a new approach based on Brouder's Lie group formulas to include both spherical wave correction and anharmonic vibration effects, which is not limited to isotropic systems. We apply partial summation technique to get a plane wave part which does not disappear even for large kR limit, and a spherical wave part which disappears for that limit. The former part has just the same cumulants as those used for plane wave EXAFS formulas, however, the latter cannot be reduced to the ordinary cumulants and is closely related to the correction factor due to thermal vibration derived by Rennert within the harmonic approximation. The plane wave part already includes spherical wave effects of photoelectron scattering. Numerical calculations for K-edge EXAFS show that spherical wave thermal factors give rise to different phase from plane wave part, which can give peak shift in Fourier transformed EXAFS spectra. The polarization dependence is also discussed.
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  • Katsuaki Kodama, Hideshi Fujishita, Hiroshi Harashina, Satoshi Taniguc ...
    Subject area: Structure of liquids and solids; crystallography.
    1995 Volume 64 Issue 6 Pages 2069-2073
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Structural parameters of BaCo1-xNixS2(0 ≤ x ≤ 1) with quasi two-dimensional electrons have been determined by the X-ray Rietveld method. This sulfide exhibits the Mott transition with varying x. The interatomic distance between Co/Ni and S(1) at the apex site of a Co1-xNixS5 square-pyramid increases with x, which is consistent with the electronic configuration (3d3z2-r2)1+x of Co/Ni ions. The structural data of BaCo0.9Ni0.1S1.85 show that the sulfur vacancies are within (Co/Ni)S planes.
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  • Masateru Tadakuma, Keisuke Tajima, Genta Masada
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1995 Volume 64 Issue 6 Pages 2074-2080
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The time evolution of the first order magnetic phase transition of cycloidal-cone spiral magnetic structure in Er single crystal has been investigated by means of the X-ray diffraction technique. The phase transition has been observed through the discontinuous change of the c lattice parameter accompanying the transition. The appreciable time delay (incubation time) for the development of the stable magnetic phase has been detected systematically, which can be interpreted by the nucleation and growth theory including the effect of the long range strain force. Experimental results also indicate that the mosaicness of the single crystal sample may affect the kinetic behavior of the phase transition.
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  • Daisuke Hamuro, Yohtaro Ueno
    Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
    1995 Volume 64 Issue 6 Pages 2081-2091
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    By means of the Monte Carlo twist method, we examine the universality of the following critical properties of the equilibrium crystal shape in the discrete Gaussian (DG) model and restricted solid-on-solid (RSOS) model: c1) a finite curvature jump at the roughening temperature TR, c2) the profile of a facet with a singularlity at the facet edge for T < TR, and c3) the radius of the facet near TR proportional to exp(-a/ 1-T/TR). We obtain the following results with the help of some results obtained analytically. The DG and RSOS models have TR=1.44 ± 0.02 and 1.60 ± 0.05, respectively. c2) is universal for these models. For the DG model c1) well agrees with the exact result of the body-centered SOS model, whereas for the RSOS model it is almost equal to twice the latter. Finite-size-scaling for c3) is excellent for the DG model, while it is consistent but inconclusive for the RSOS model.
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  • Takeshi Nakanishi, Tomi Ohtsuki, Motohiko Saitoh
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 6 Pages 2092-2099
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Electronic states of a two-dimensional tight-binding lattice with finite size in the presence of both uniform electric and magnetic fields are studied. Numerical solutions for eigenenergies are presented. The magnetic subbands at zero electric field known as the Hofstadter butterfly are modified by the electric field and the eigenenergies for high electric fields are represented by the Stark ladder states associated with each of the magnetic subbands. When the electric potential drop across the system becomes comparable to the bandwidth of zero field, the density of states becomes the pyramid shape with steps, the steps being induced by the finiteness of the lattice. The influence on the density of states by the change of the direction of the electric field is also discussed.
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  • Susumu Okada, Susumu Saito
    Subject area: Electron states in condensed matter.
    1995 Volume 64 Issue 6 Pages 2100-2105
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    We study the electronic structure of C78 and that of C78-graphite cointercalation compound. First we show the electronic structure of five isomers of C78. Their geometric structures have been optimized by an empirical model potential and their electronic structure has been calculated using the tight-binding model. The C2v-symmetry C78, a major isomer experimentally extracted, is found to have a considerably deep lowest unoccupied state. Using this C2v C78, we design a stage-1 C78-graphite cointercalation compound. Its electronic structure calculated with the tight-binding model shows that the deep lowest unoccupied state of the C2v C78 causes charge transfer from a graphite sheet to C78. Although the material is formed with only carbon atoms, C78-graphite cointercalation compound is the hole doped graphite intercalation compound.
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  • Makoto Kuwabara, Yoshiyuki Ono
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 6 Pages 2106-2117
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The activation energy of a charged soliton pinned by a dopant ion is numerically studied as a function of the dopant concentration. To investigate this problem, use is made of Su-Schrieffer-Heeger's model modified to involve the long-range potential due to the dopants. The dopants are assumed to form a regular lattice even in the low concentration region. The activation energy is defined by the energy difference between a state where the soliton is pinned by a dopant and another state where the soliton locates at a mid point between neighboring dopants. It is shown that the activation energy decreases rapidly with increase of the dopant concentration. It is also found through introducing the effect of the intrachain electron-electron interactions that the soliton width is one of the essential factors in determining the activation energy. The threshold electric field for the depinning of the charged soliton from a dopant is also numerically investigated by dynamical simulations. As expected from the results of the activation energy the threshold field decreases rather rapidly as the concentration increases.
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  • Sakae Todo, Kiiti Siratori, Shigeyuki Kimura
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 6 Pages 2118-2126
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Electrical conductivity and Hall effect were measured for the high temperature phase of Fe3O4 single crystals with different stoichiometry, in an external magnetic field up to 27, kOe. It was confirmed that the transport properties do not depend so much on stoichiometry, in contrast to the low temperature phase. Temperature dependence of the conductivity and magnetoresistance as well as extraordinary Hall coefficient which changes sign at 650, K indicate that not only 3d electrons of Fe ions in the B site but also of those in the A site and/or 2p electrons of O ions contribute to the transport above 400, K. Below 250, K, extraordinary Hall coefficient is proportional to ρ0.5. The results of the present experiments are discussed in connection with previous reports. Formation of large polarons below 250, K is suggested.
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  • Ki–ichi Nakamura
    Subject area: Electronic transport in condensed matter.
    1995 Volume 64 Issue 6 Pages 2127-2137
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    A computer simulation using particles was performed to investigate the mechanism for the noisy acoustoelectric voltage oscillations in dc-current-driven piezoelectric semiconductors. It is demonstrated clearly that the noisy voltage oscillations are due to the successive occurrence of the electron avalanche transfer where bunches of electrons trapped in the troughs of piezoelectric potential associated with the acoustic phonons amplified from the thermal background escape simultaneously into other troughs. The time series analysis suggests that the oscillations are not random noise but low-dimensional chaos.
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  • Hiroki Onoe, Akihiko Sumiyama, Masahito Nakagawa, Yasukage Oda
    Subject area: Superconductivity.
    1995 Volume 64 Issue 6 Pages 2138-2143
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The thickness of the Meissner region ρ in Au of Au-clad Nb wire has been measured down to 50, mK, in order to investigate the superconductivity in a normal metal induced by the proximity effect. The magnetic field dependence of ρ and the Josephson critical current IC through a SNS junction made of an Au-clad Nb wire have been also measured to estimate the coherence length ξN in Au. Above 150, mK, ρ and ξN increase in proportion to T-1, and are independent of the mean free path lN in Au. Although Au is in the clean limit (lN > ξN), these results can be qualitatively interpreted by the dirty limit theory with a modification using ξN derived in the clean limit.
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  • Hiroshi Kageyama, Kazuyoshi Yoshimura, Masaki Kato, Koji Kosuge
    Subject area: Superconductivity.
    1995 Volume 64 Issue 6 Pages 2144-2146
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Hole concentration, h, was determined by using the coulometric titration technique for the powdered samples of La2-xSrxCuO4+δ (0 ≤ x ≤ 0.02) annealed in flowing 1, atm N2 and 1, atm O2. From the temperature dependence of magnetic susceptibility we found that the Néel temperature, TN, decreases steeply with increasing h and that TN(h) can be fitted in the following expression TN(h)/TN(0)=1- {h/hc}n where TN(0), hc and n are constants. This power-law dependence might be explained by finite size scaling theory.
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  • Hijiri Kito, Susumu Isida, Masaru Suzuki, Jun Akimitsu, Shunji Takekaw ...
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2147-2151
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Velocities and attenuations of longitudinal sound waves were measured at 100, MHz for a single crystal of non-stoichiometric ErFe2O4-δ , along the ‹ 0, , 0, , 1› and ‹ 1, , 1, , 0› axes in the hexagonal frame, below 300, K. At room temperature, velocities were 5.22× 103 and 5.49× 103, m/s along the ‹ 0, , 0, , 1› and ‹ 1, , 1, , 0› axes, respectively. These values correspond to the elastic constants of C11=1.94× 1012, dyne/cm2 and C33=1.75× 1012, dyne/cm2. Slight softening was disclosed along the ‹ 0, , 0, , 1› axis at around 240, K. Correspondingly, a large peak was observed in the attenuation. These anomalies are attributed to the emergence of two-dimensional spin ordering in this crystal at this temperature. On the contrary, no anomaly was detected along the ‹ 1, , 1, , 0› axis at around 240, K, with rather high attenuation level almost independent of temperature. This absence of anomalies was discussed on the existence of three kinds of magnetic domains. Development of the correlation of Er spins was suggested below 30, K.
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  • Shoji Ishida, Shinpei Fujii, Shoei Kawhiwagi, Setsuro Asano
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2152-2157
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Electronic structures of Heusler alloys Co2MnZ (Z=sp elements) were calculated to search half-metallic compounds. In this paper, it will be shown that stoichiometric compounds Co2MnZ are half-metallic when Z is Si and Ge. Considering the effect of Z atom on the band structure, we can predict that there are half-metallic compounds in nonstoichiometric compounds Co2MnZ1-xZx' and that the position of the Fermi level is adjustable in the energy gap of the minority-spin state by changing the composition x.
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  • Noriko Tanemura, Yoshikazu Suzumura
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2158-2165
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The fluctuation around the molecular field of the spin density wave (SDW) state has been examined by calculating the collective modes and the spectral weight as a function of arbitrary strength of the repulsive on-site interaction, U, for a one-dimensional system with the half-filled band. The transverse mode is well described by the spin wave for both the small U and the large U and takes the spectral weight which is dominant compared with that of the longitudinal mode for the large U. The temperature dependence of the static magnetic susceptibility is calculated for both the longitudinal and transverse cases.
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  • Naoshi Suzuki, Junichi Makino
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2166-2174
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Effects of magnetic fields on the magnetic excitation of hexagonal singlet-ground-state magnet CsFeCl3 are studied on the basis of the dynamical correlated-effective-field theory. First, the single-ion anisotropy energy D and the intrachain (interchain) exchange integral J1 (J2) are determined so as to reproduce the observed magnon energies of particular k-points at T=5, K: D=14, cm-1, J1=2.59, cm-1 and J2=-0.14, cm-1. The value of D is almost the same as that of RbFeCl3, but the magnitudes of J1 and J2 are smaller than those of RbFeCl3. The calculated field dependence of the magnon energies at the Brillouin zone center agrees well with the experimental data obtained by ESR measurements. The magnetic excitation of CsFeBr3 with antiferromagnetic intrachain exchange interaction is also calculated and the results are compared with those of CsFeCl3.
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  • Kazuko Inoue, Yoji Nakamura, A. V. Tsvyashchenko, L. Fomichiva
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2175-2182
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The temperature dependence of magnetic susceptibility and magnetization of metastable C14-RMn2 (R=Y, Gd, Tb, Dy and Yb), synthesized at high pressures, has been measured. YMn2 is an itinerant paramagnet over the whole range of temperatures. GdMn2, TbMn2 and DyMn2 are ferromagnetic at low temperatures, while their susceptibilities beyond TC obey the Curie-Weiss law. YbMn2 is a paramagnet down to 4.2, K whose susceptibility suggests antiferromagnetic interactions. These magnetic properties are discussed together with those of other stable C14-RMn2. Similary to stable C14- and C15-RMn2, the appearance of local magnetic moments of itinerant 3d Mn electrons of C14-RMn2 at low temperatures are determined by the Mn--Mn distance. The Mn atom has a magnetic moment for light rare earths, whereas no moment for heavy rare earths. The critical substance for the onset of Mn moments is TbMn2.
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  • Koji Hukushima, Koji Nemoto
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2183-2190
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    We study the spin dynamics of the 3D± J Ising model in high temperatures. The spin autocorrelation function can be expressed in terms of the eigenvalues of the interaction matrix in the high temperature limit. We obtain the true asymptotic behavior by evaluating the eigenvalues and find that the short time behavior is well described by the stretched exponential law.
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  • Koji Honda, Hideyuki Sato, Yuji Aoki, Satoru Araki
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2191-2197
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    One of the authors (S.A) has first reported that Co/Ag is one of rare examples in MBE-grown multilayers which show the magnetoresistance (MR) oscillations as a function of non-magnetic layer thickness, while an important contribution from a granular-like component has been pointed out recently. In order to investigate the basic mechanism of the large MR in this system, we made a precise comparison of the zero-field cooled and the field cooled curves both in the resistivity and the magnetization. A scaling relation between the extraordinary Hall resistivity and the magnetoresistance has also been investigated. Some cooperative interaction between the interlayer coupling and the granular-like component is found to be important.
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  • Hideto Imai, Hirofumi Wada, Masayuki Shiga
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2198-2202
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The specific heat measurements of YMn2 and Y0.97Sc0.03Mn2, which exhibit giant spin fluctuatuions in the paramagnetic state, were carried out in the temperature range of 13, K to 300, K. The spin fluctuation contribution to the specific heat Cm was estimated by subtracting the phonon and electronic parts. The magnetic entropy Sm was deduced from Cm. Above 120, K, where the the effect of the antiferromagnetic transition vanishes, the entropy curves of two compounds coincide each other, indicating that in the paramagnetic state, YMn2 has the same amplitude of spin fluctuations as Y0.97Sc0.03Mn2. The absolute value of the entropy was also discussed taking account of results of neutron scattering measurements.
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  • Ko–ichi Hiraki, Yoshiaki Kobayashi, Toshikazu Nakamura, Toshihir ...
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1995 Volume 64 Issue 6 Pages 2203-2211
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The antiferromagnetic state of the title compound has been investigated by the measurements of 1H-NMR lineshape and nuclear spin-lattice relaxation rate, T1-1, on a single crystal sample. Below the Nèel temperature, TN -- 6.7, K, the resonance line was observed to split into three pairs of peaks. The angular dependence of the lineshape has revealed the magnetic structure of this compound; i) the antiferromagnetic moments are localized at Cu2+ sites and are regularly ordered with a three-fold periodicity along the stacking c-axis; ii) the easy axis is in the ab-plane and the c-axis is the hard axis; iii) a model of the three dimensional arrangement of the magnetic moments well explaining the experimental results is proposed.
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  • Yukio Tagawa, Naoshi Suzuki
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 6 Pages 2212-2224
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    Optical absorption spectra associated with non-linear excitations in halogen-bridged mixed-valence Pt complexes Pt-X (X=Cl, , Br, , I) are investigated theoretically on the basis of the one-dimensional single-band Peierls-Hubbard model. The expressions for the zone-center phonon frequencies in the CDW state are derived by calculating the second order expansion coefficients of the adiabatic potential. Then, the parameters in the model Hamiltonian are determined by utilizing the observed values of the energy gap, the halogen displacement and the frequencies of the zone-center phonons. The optical absorption spectra associated with the non-linear excitations such as solitons and polarons are calculated, and the origins for the three lines of photo-induced mid-gap absorption observed in each Pt-X are assigned as follows. In Pt-Cl all the three lines are due to polarons. In Pt-Br and Pt-I, on the other hand, two of the three lines are due to polarons, but the remaining one is due to charged-solitons.
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  • Satoshi Tanaka, Haruhiko Ogasawara, Kozo Okada, Akio Kotani
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1995 Volume 64 Issue 6 Pages 2225-2232
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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    The 4d → 2p X-ray emission spectra (XES) of Ce2O3, Pr2O3 and Dy2O3 have been calculated with an impurity Anderson model with the full multiplet couplings, following the Kramers-Heisenberg formula in the second order optical process. Experimental results have been well reproduced with this model by using a constant value for the 4d core hole lifetime damping Γ (4d) in the case of Ce2O3 and Pr2O3, while in the case of Dy2O3 it is necessary to take into account the term dependence of Γ (4d), which is consistent with the previous theoretical analyses of 4d X-ray photoemission spectra. It was also shown that both the spin-orbit couplings of the 4d core level in the final state and the 4f level in the initial state are key factors to cause the branching ratio in the Lγ line larger than that in the Lβ line. The phase matching of the wave functions between the intermediate and final states smears out the hybridization effect in the 4d → 2p XES in Ce2O3 and Pr2O3.
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  • Michiaki Matsukawa, Katsushi Hashimoto, Noriyuki Yoshimoto, Masahito Y ...
    Subject area: Thermal properties of condensed matter.
    1995 Volume 64 Issue 6 Pages 2233-2234
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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  • Yutaka Kaneko
    Subject area: Transport properties of condensed matter (nonelectronic).
    1995 Volume 64 Issue 6 Pages 2235-2236
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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  • Kitomi Tsutsumi, Shigeru Takayanagi, Masayasu Ishikawa, Toshiyuki Hira ...
    Subject area: Superconductivity.
    1995 Volume 64 Issue 6 Pages 2237-2238
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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  • P. Reed
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2239-2240
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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  • Hiroshi Yoshie, Toru Kojima, Masahide Hoshino, Yasushi Amako, Hiroyuki ...
    Subject area: Magnetic properties and materials.
    1995 Volume 64 Issue 6 Pages 2241-2242
    Published: June 01, 1995
    Released on J-STAGE: October 01, 1999
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