Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 54, Issue 6
Displaying 1-44 of 44 articles from this issue
  • Jiro Mizushima, Kanefusa Gotoh
    1985 Volume 54 Issue 6 Pages 2061-2064
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    An improved theory is proposed to remove a defect of the existing nonlinear stability theory in the problems of subcritical parallel flows. Basic idea is to treat the fundamental mode and the mode of basic-flow distortion impartially. A couple of amplitude equations have been derived corresponding to the Landau equation for the system of single fundamental mode. The theory should be applied to the flows characterized by the spectra of the amplification rate in the linear theory having some comparable extreme values for both modes.
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  • Yoshiomi Kondoh
    1985 Volume 54 Issue 6 Pages 2065-2068
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Numerical results for various types of equilibria in the partially relaxed, minimum-energy states are presented. It is shown that there exists a maximum point of available beta-value in the Screw-pinch type with relatively low current density without the pitch minimum. The available beta-value for the reversed-field-pinch becomes larger in the partially relaxed states dominated by the helical tearing modes with higher toroidal mode numbers.
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  • Minoru Tanaka
    1985 Volume 54 Issue 6 Pages 2069-2072
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Short-range order in the rapidly quenched states of Lennard-Jones liquid (argon) and simple liquid metal (rubidium) both simulated by the molecular dynamics method is compared with each other. The pair and the triplet distribution functions show typical amorphous structures in both of the states, and obey a law of corresponding states with the mean atomic distance as a scaling parameter. The self-diffusion constant D during the rapid-quenching process seems also to obey a law of corresponding states with the depth of the minimum of the pair potential as another scaling parameter. These similarities suggest that the local arrangement of atoms in an amorphous state of monatomic substance is determined by a common principle irrespective of the nature of interatomic pair potentials.
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  • J. Lakshmana Rao, Asako Kawamori, Katsumi Miyazaki, Keisuke Suzuki
    1985 Volume 54 Issue 6 Pages 2073-2076
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Optical absorption spectrum of Cu2+ ions doped in ammonium bromide(acidic) has been studied in the temperature range from 300 K to 173 K. From the observed spectrum, it is concluded that Cu2+ is incorporated interstitially. An abrupt blue shift or about 100 cm−1 is observed at 232 K at the position of the band maximum assigned to the transition 2A1g2Eg and this is attributed to the ordering of coordinated water molecules. It is suggested that the divalent copper ion has a fourfold bromine coordination associated with two neutral water molecules at the first neighbor NH4+ sites along [001] direction.
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  • Yoshikazu Suzumura
    1985 Volume 54 Issue 6 Pages 2077-2080
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    By use of the method in the previous paper [J. Phys. Soc. Jpn. 53 (1984) 3918], we study the Anderson localization in a one-dimensional half-filled extended Hubbard model with randomness. A transition from localization into delocalization takes place as the attractive interaction for superconductivity increases. It is shown that the effect of localization on singlet superconductivity (SS) is stronger than that on triplet superconductivity (TS) due to the large quantum fluctuation of TS compared with that of SS.
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  • Masao Yamamoto
    1985 Volume 54 Issue 6 Pages 2081-2083
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    In zinc, a compensated metal, the excitation of helicon wave has been observed in as low magnetic field as 2 kOe for the field direction along [0001] by the magnetic breakdown. The propagation of wave exhibits the spin splitting of quantum oscillation. From the analysis of the data it has been confirmed that the oscillation is associated with the ‘needle’ of electron Fermi surface and the absolute value of the effective g factor has been ascertained as 175.
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  • Keizo Murata, Madoka Tokumoto, Hiroyuki Anzai, Hiroshi Bando, Gunzi Sa ...
    1985 Volume 54 Issue 6 Pages 2084-2087
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Low temperature phase diagram of β-(BEDT–TTF)2I3 as a function of pressure (P) is determined by resistivity measurement. The superconducting transition temperature (Tc) rises from 1.1–1.5 K (P=0 kbar) to around 7.4 K (P=1.3 kbar) and decreases to 1.2 K (P=7 kbar). We propose that two kinds of superconducting states exist in this salt and that ambient pressure gives two stable states which have Tc’s of around 8 K as well as around 1.3 K. The upper critical field, Hc2, along the c*-axis is also presented.
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  • Toshihiro Yoshioka, Yûichi Tazuke
    1985 Volume 54 Issue 6 Pages 2088-2091
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Magnetization and ac-susceptibility of polycrystalline FexTiS2 are measured. For x<0.38, a maximum in the ac-susceptibility is found and no spontaneous magnetization is observed. These behaviours indicate spin-glass like freezing. On the other hand, ferromagnetic properties are found for 0.38≤x≤0.42. The present results are discussed from the point of view that the compounds are the competing spin system having both ferromagnetic and antiferromagnetic interactions. Magnetic phase diagram is presented as a function of x.
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  • Hidetoshi Fukuyama
    1985 Volume 54 Issue 6 Pages 2092-2095
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    The effect of Anderson localization on the weak ferromagnetism has been examined in the weakly localized regime by extending to dirty systems the self-consistent renormalization theory of spin fluctuations developed so far for clean systems. The result indicates that the relative change of the Curie temperature due to disorder can be appreciable for weak ferromagnets with low Curie temperatures.
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  • Toshiya Nagahama, Michihiro Kobayashi, Yuichi Akahama, Shoichi Endo, S ...
    1985 Volume 54 Issue 6 Pages 2096-2099
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Three components of dielectric constant along three principal crystal axes in black phosphorus are determined for the first time. Two of them are obtained from far-infrared interference spectra for thin cleaved samples. The remaining one is determined by analyzing far-infrared absorption peaks observed in p-type sample at 1.4 K, which are ascribed to optical transitions from the acceptor ground state to its excited states.
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  • Masato Yoshimori, Hiroyuki Watanabe
    1985 Volume 54 Issue 6 Pages 2100-2103
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Energy spectra of accelerated protons at flare sites are derived by comparing the observed ratios of the 4.44 MeV gamma-ray line fluence to the 2.22 MeV gamma-ray line fluence with the calculated ratios. The proton spectra derived for the 1981 Apr. 1, 1981 May 13, 1981 Oct. 15 and 1982 June 6 disk flares do not much vary from flare to flare, and are in agreement with average proton spectra observed in interplanetary space within the errors. It implies that both the protons which produce gamma-ray lines at the Sun and those which escape from the Sun are probably accelerated by the same mechanism.
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  • Akira Nakamura
    1985 Volume 54 Issue 6 Pages 2105-2109
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    We present a generalization of the cylindrical KdV equation. The new equation has been shown to be completely integrable soliton equation. We have found the exact explode-decay soliton solutions to the equation. The soliton is written by the Bessel function. This agrees with the previous conjecture that the 2+1 dimensional explode-decay solitons are always written by the special function such as Bessel function.
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  • Youji Yamashita
    1985 Volume 54 Issue 6 Pages 2110-2121
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    By making use of the transport theory, the emergence-angle-dependent energy losses of high energy ions are calculated. It is emphasized that we must take into account the scattering by the atomic electrons as well as the nucleus to discuss the scattering-angle-dependent energy loss in a single collision with the target atom. The treatment of the problem is devided into the following three cases; a) large atomic number case of the target material (for example copper), b) medium (aluminum, etc.) and c) small (beryllium, etc.). The dependence on foil thickness and emergence angle of the theoretical value of the emergence-angle-dependent energy loss agrees well with the experimental results.
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  • Kazuo Takayanagi, Takashi Wada
    1985 Volume 54 Issue 6 Pages 2122-2131
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    The resonant rotational energy transfer of the type M(J=1)+M(J=0)→M(J=0)+M(J=1) has been studied theoretically. M(J) is a linear polar molecule with the rotational quantum number J. The impact-parameter PRS (Perturbed Rotational State) and the impact-parameter CC (Close-Coupling) methods are applied. The straight-line trajectory and the pure dipole-dipole interaction are assumed. Validity of these simplifying assumptions is discussed. It is found that the energy transfer cross section becomes very large at low collision velocities and that it increases rapidly as the velocity decreases. The results are applicable to any identical linear polar molecules as long as the basic assumptions stated above are valid. For HF+HF, the theoretical prediction is compatible with the recent experimental findings by Vohralik and Miller at the collision energy 0.15 eV.
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  • Shigeo Kida
    1985 Volume 54 Issue 6 Pages 2132-2136
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    A class of three-dimensional periodic flows of an incompressible viscous fluid with high symmetry in space is proposed to be used for numerical simulation of large Reynolds number flows in order to increase the effective resolution. Information for a single component of the velocity in a domain of 1/64 in volume of a periodicity box is sufficient to describe the whole velocity field. Necessary memory therefore may be reduced to 1/192 of that required for a general non-symmetric periodic flow.
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  • Kazuhiro Tsuboi, Yuko Oshima
    1985 Volume 54 Issue 6 Pages 2137-2145
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Interaction of two dimensional vortex blobs with finite core, particularly their convective merging, is investigated numerically by the use of the discrete vortex method, in which each vortex blob is replaced by a group of a number of point vortices. The numerical experiment is performed for the two cases. One is the interaction of two identical vortex blobs, and the other is the interaction of three vortex blobs with the same strength, where two of them have a like-signed circulation and the rest has the opposite. The results clarify the process of convective merging of two like-signed vortices and the effect of the third opposite-signed vortex to the merging.
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  • Mitsuru Yamagiwa, Toshinori Michishita, Masao Okamoto
    1985 Volume 54 Issue 6 Pages 2146-2154
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    We study time evolution of electron distribution function with a long tail during applying of lower hybrid waves for the purpose of effective current sustainment. We solve numerically two dimensional Fokker-Planck equation combining with the quasi-linear diffusion effects due to both the applied lower hybrid waves and the excited plasma waves of ω=ωpe cos Θ.
    We find that the plasma waves excited due to the resonances with electrons near above the thermal velocity play an important role of a recovery of the flat tail against the destroy of it due to the Coulomb collisions; the quasi-linear diffusion effects are strengthened in the velocity region of the inverse Landau damping.
    We discuss the possibility of the effective current sustainment making use of this mechanism.
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  • Kiyomitsu Suzuki
    1985 Volume 54 Issue 6 Pages 2155-2159
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Two dimensional equilibria of field reversed configuration with plasma outside the separatrix is investigated. By numerical calculation, it is found that the separatrix (ψ=0) becomes spindly as βs (beta ratio on the surface ψ=0) increases. Remarkable is that the surface ψ=0 becomes an open surface and no more the separatrix as βs increases beyond a critical value, and furthermore, that only axially uniform configurations are obtained when βs is greater than a second critical value. Existence of the critical values of βs can be explained also with use of a long thin plasma model and a condition of axial force balance which takes into account the plasma outside the separatrix. The critical values obtained with this model well agree with the two dimensional numerical results as well as radii of the plasma both at the center plane and at the ends of vessel.
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  • Katsuji Chiyoda
    1985 Volume 54 Issue 6 Pages 2160-2162
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    A stability analysis against the interchange mode of the Hill vortex model in a field-reversed configuration is made by use of the result of Bernstein and others. A stability condition is given. The equilibrium configuration considered here is found to be unstable to the interchange mode.
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  • Masayoshi Taguchi, Takeshi Miyazaki, Shobu Kaneko
    1985 Volume 54 Issue 6 Pages 2163-2167
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    The stability of axially symmetric force-free equilibrium plasma is investigated. As a model of the flux conserver, a toroidal vessel with a rectangular cross section is considered. The radii of the inner and the outer walls of the vessel are denoted by Ri and R, and the height h. The plasma is shown to be stable for the ideal magnetohydrodynamic perturbations when hR<(hR)*, and unstable when RiR<0.11 and (hR)*<(hR)<(hR)+. The values of the critical ratios (hR)* and (hR)+ are evaluated as a function of RiR.
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  • Moriji Mizoguchi
    1985 Volume 54 Issue 6 Pages 2168-2183
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Experimental results by NMR are most powerful to determine the microscopic electron ordering structure of magnetite. In a previous paper, we determined the fundamental electron ordering structures by arranging the Fe3+ ions which were characterized by the assortment of the nearest neighbour cations. In this paper, we divide the fundamental electron ordering structures into unit patterns, which correspond to the resonance lines, and construct a new structure by mixing and jointing again these unit patterns. The new model is a twinning structure, x-y twin, of two kinds of the “normal” electron ordering patterns. The structure is fundamentally bundle structure and is possibly a layer structure which is formed by layered twin boundaries. This model gives good agreement with the NMR results even in the intensity ratio of the resonance lines and with the extinction rule of the diffraction spots. The newly proposed structure is a key to the solution of many strange behavior of magnetite at low temperature.
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  • Yoshiyuki Morioka, Koshiro Toriumi, Tasuku Ito, Akira Saito, Ichiro Na ...
    1985 Volume 54 Issue 6 Pages 2184-2189
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Crystals of K3Fe(CN)6 undergo a second-order phase transition accompanied by a soft mode at about 130 K. The crystal structures of the room- and low-temperature phases have been determined by X-ray diffraction. Crystals of the room-temperature phase are monoclinic with space group P21c, a=7.058(1), b=10.426(1), c=8.401(1) Å, β=107.31(1)° and Z=2 at 293 K. Those of the low-temperature phase are monoclinic with space group P21n, a=14.021(2), b=10.401(1), c=8.339(2) Å, β=107.21(1)° and Z=4 at 100 K. Final R values were 0.029 for 1591 observed reflections and 0.027 for 2642 observed reflections for the room- and low-temperature phases respectively. With a transition from room- to low-temperature phase, [Fe(CN)6]3− anions displace by about 0.1 Å along the b axis. A soft mode is considered to be a translational lattice mode of [Fe(CN)6]3− anions which has a wave vector a*⁄2 in the room-temperature phase.
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  • Hiroaki Kamioka, Yoshio Sumino
    1985 Volume 54 Issue 6 Pages 2190-2193
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Temperature variation of the attenuation in indium has been measured by the pulse transmission method in the temperature range from 120 to 183°C through the melting temperature of 156.4°C. The frequency of sound was 1 MHz. The value of attenuation in solid phase just below the melting point was 0.154 neper/cm, and that in liquid phase just above the melting point was 0.123 neper/cm. At the melting point, a large absorption of ultrasonic wave was seen and its value amounted to 0.273 neper/cm in the melting process and 0.539 neper/cm in the solidification process. The increase of the attenuation at the melting point may be due to the Rayleigh scattering, which is appreciable in the mixed state of the liquid and the suspending crystallites.
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  • Motoyuki Tanaka, Takeshi Kawabe
    1985 Volume 54 Issue 6 Pages 2194-2203
    Published: June 15, 1985
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    Phase transitions of a spin-one Ising model with positive biquadratic interaction are investigated using a Monte Carlo method for a square lattice in comparison with the molecular-field results obtained from a two-sublattice model. Phase diagrams characterizing phase transitions of the model are presented for representative values of energy parameters and compared with those obtained from the molecular-field theory and other theories. It is shown that there exist no successive phase transitions as predicted from the molecular-field theory for any value of energy parameters we dealt with. Multicritical points on phase boundaries are estimated from the data to give reasonable values compared with those of other theories.
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  • Hideo Hama
    1985 Volume 54 Issue 6 Pages 2204-2209
    Published: June 15, 1985
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    The effects of a magnetic field on the nematic-smectic A phase transition in liquid crystals are investigated within the framework of McMillan’s molecular field theory. It is shown that the tricritical point (TCP) can appear on the nematic-smectic A phase boundary as the magnetic field increases. The phenomenological de Gennes formula under the magnetic field is also derived from the molecular field theory. The critical value of the magnetic flux density inducing the TCP is estimated to be of about 500 T for TBBA. It is also pointed out that an electric field of about 500 kV/cm can induce a TCP as well, which might be attainable experimentally under favorable conditions.
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  • Isao Harada, Koichi Takasaki
    1985 Volume 54 Issue 6 Pages 2210-2217
    Published: June 15, 1985
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    The phase diagram of the square-lattice ANNNI (axial next nearest-neighbor Ising) model in an external field is calculated by the interface method of Müller-Hartmann and Zittartz. In the ANNNI model, next nearest-neighbor interactions are assumed to be antiferromagnetic whereas others take both ferromagnetic and antiferromagnetic values. The stability of various commensurate phases predicted for the ground state are examined against the formation of an interface separating two different regions, each consisting of one of the degenerate ground states. The phase diagrams display different commensurate phases having no common boundary between them so that the critical temperature is zero on the multiphase boundaries. For a certain set of parameters, the phase diagram is favorably compared with the Monte Carlo result obtained by Rujan and co-workers.
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  • Koji Honma, Keiichi Iida
    1985 Volume 54 Issue 6 Pages 2218-2228
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Specific heat capacities of “superionic conductor” Ag chalcogenides have been measured mainly for Ag2TexS1−x in the temperature range, 120–520 K. There is no indication of α-β transition except for x=0.1. Instead, a very broad peak of heat capacity is found at about 210 K for x=0.2–0.6. Using the method that H. Wiedersich and W. V. Johnston [J. Phys. Chem. Solids 30 (1969) 475] applied to RbAg4I5 and assuming that the structure of Ag2TexS1−x is α-Ag2S or α-Ag2Te-like, the excess heat capacity can be explained fairly successfully as the transition of Ag+ ions between two or more types of sites.
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  • Hirohide Nakamatsu, Yuko Azuma, Hirohiko Adachi, Shichio Kawai
    1985 Volume 54 Issue 6 Pages 2229-2237
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    The electronic structure and bonding character of β-LiAl has been studied by a molecular cluster model to clarify the electronic effects on the Li diffusion. The interactions of Li–Li, Li–Al and Al–Al are discussed using the Mulliken population analysis. It is found that the Li–Al and the Al–Al bonds are relatively strong, compared with the Li–Li one. The Li–Al bond is considered unfavorable for the Li diffusion. A formation of Li vacancy causes a redistribution of electron density which effectively contributes to the stabilization of the system. It is also found that the electron distribution in the Li–Al bond changes into a favorable one for the Li diffusion when the vacancy is formed.
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  • Tsuneya Ando, Hideo Aoki
    1985 Volume 54 Issue 6 Pages 2238-2249
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    The electron localization in the two-dimensional system in strong magnetic fields is investigated by the finite-size scaling method. The scaling function numerically obtained for macroscopically long systems shows that the single-parameter scaling is invalid. The inverse localization length, α, is shown to have a power law dependence on energy around the center of the Landau level, EN, with α(E)∝|EEN|s. For short-range scatterers, the critical exponent, s, is found to be close to 2(4) for N=0(1) Landau level, while the localization is much stronger for long-range scatterers.
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  • Sadao Takaoka, Kazuo Murase
    1985 Volume 54 Issue 6 Pages 2250-2256
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    The plasma frequencies (ωp) of epitaxially grown bismuth film on BaF2 are determined from the far-infrared reflectivity as a function of film thickness (d). With decreasing d, ωp increases at first and then decreases abruptly near d=100 A. This is considered as a sign of semimetal-semiconductor transition caused by the quantum size effect. The temperature dependences of ωp and its damping factor are also measured with various d. The cyclotron mass of the electron band increases with decreasing d. To explain these experimental results, the strain effects of the film due to the lattice mismatch between the film and the substrate have to be taken into account.
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  • Hiromichi Ebisawa, Hidetoshi Fukuyama, Sadamichi Maekawa
    1985 Volume 54 Issue 6 Pages 2257-2268
    Published: June 15, 1985
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    Our former investigation for the effects of localization on the superconducting critical temperature of thin films are extended to much dirty cases where τ−1>>ωD, ωD being the Debye frequency, but still in the weakly localized regime, i.e. h⁄(2πEFτ)<1, EF and τ being the Fermi energy and the life time, respectively. The depression of the critical temperature to the first order in h⁄(2πEFτ) is shown to be proportional to the inverse of the film thickness, 1⁄d, i.e. to the sheet resistance (Remark: Graphics omitted.), in the wide range of the thickness within the present region of interest where \sqrthDkBT>>d>>l, D being the diffusion constant, T the temperature and l the mean free path. The proportionality factor depends on the details of the interaction processes among electrons.
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  • Harukazu Igarashi
    1985 Volume 54 Issue 6 Pages 2269-2278
    Published: June 15, 1985
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    The isotropic quantum Heisenberg antiferromagnet at T=0 is studied using the renormalization group method for perturbation expansion of the Dyson-Maleev spin wave model in the inverse of the spin size S. The exponent η which characterizes the correlations as ⟨s(r)s(0)⟩∼(1⁄r)d−1+η is given in powers of ε as η\simeq−2ε2. The result does not agree with that of now-linear σ-model in two dimension.
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  • Masatoshi Arai, Yoshikazu Ishikawa, Humihiko Takei
    1985 Volume 54 Issue 6 Pages 2279-2286
    Published: June 15, 1985
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    The spin correlation in a reentrant spin glass of 79FeTiO3-21Fe2O3 has been studied by neutron scattering from a single-crystal. The spin correlation parallel and perpendicular to the c-axis has been separately discussed. It has been found that the squared Lorentzian type spin correlations between perpendicular components develop below the ferromagnetic transition temperature. The reentrant spin glass transition temperature defined as the temperature where the magnetization starts to decrease has been found to correspond to the temperature where the parallel (transverse) components appear and the system is devided into large domains with the canted spin structure.
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  • Shigeru Takagi, Hiroshi Yasuoka
    1985 Volume 54 Issue 6 Pages 2287-2292
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    The temperature dependence of the magnetic susceptibility and the magnetization curve in the ground state of a nearly ferromagnetic itinerant electron system TiBe2 are discussed based on the unified theory of spin fluctuations developed by Moriya and Takahashi. (1) A maximum in χ(T) at around 10 K and the Curie-Weiss law of χ(T) above about 30 K, and (2) a maximum in MH and a good linearity of the Arrott plot under higher fields at low temperatures can be explained consistently with semi-quantitative success by using a model density of states introduced by taking account of the results of band structure calculations.
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  • Takafumi Kita, Yukito Tanabe
    1985 Volume 54 Issue 6 Pages 2293-2303
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    The line shapes of the optical transition (Remark: Graphics omitted.) of Cr3+ in GdAlO3 are calculated. All the local exchange interactions around the Cr3+ ion, including Gd3+–Gd3+ ones, are taken into account to determine the eigenstate of the 4A2 state and of the 2E state. Possible mechanisms for the transition are considered and selection rules are obtained for each mechanism. From the comparison of the theoretical curves with the experiments, the magnitudes of the Cr3+–Gd3+ exchange integrals are predicted to be −1.0 cm−1 for the 4A2 state and −0.55 cm−1 for the 2E state. The agreement between the theory and the experiment is fairly good.
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  • Takafumi Kita, Yukito Tanabe
    1985 Volume 54 Issue 6 Pages 2304-2310
    Published: June 15, 1985
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    The ground configuration of Gd3+ spins with a Cr3+ spin at an Al3+ site is investigated theoretically by treating spins as classical axial vectors. It is found that the eight nearest-neighbour Gd3+ spins around the Cr3+ spin align ferromagnetically or antiferromagnetically, according as the maximum of the molecular field on each Gd3+ site which is caused by the Cr3+–Gd3+ exchange interaction is larger or smaller than that caused by the six Gd3+–Gd3+ ones. The result is interesting in connection with the spectrum of Cr3+ in GdAlO3 below TN=3.9 K.
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  • Prem Chand, G. C. Upreti
    1985 Volume 54 Issue 6 Pages 2311-2316
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    The EPR of Mn2+ in NH4Br single crystals has been studied at X-band in the temperature range from 573 K to 77 K. At room temperature, an isotropic spectrum (spectrum-I) comprising a sextet superimposed on a broad line is observed. On heating the crystal up to 400 K the sextet disappears due to explulsion of Mn2+ impurity from the crystal. On lowering the temperature, the isotropic spectrum-I disappears about at 230 K and a new spectrum (spectrum-II) appears below this temperature. The spectrum-II is highly anistropic and unusual and is believed to be due to very large zero field splitting of Mn2+. Spectrum-I is attributed to Mn2+ ions substituting for NH4+ with charge compensating NH4+ vacancies far away from Mn2+. The transformation of spectrum-I into spectrum-II is attributed to the structural transformation of NH4Br.
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  • Mitsuhiro Motokawa, Chiaki Uyeda, Akihiro Otsuka, Muneyuki Date, Rober ...
    1985 Volume 54 Issue 6 Pages 2317-2322
    Published: June 15, 1985
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    Impurity spin resonance of Mn2+ in antiferromagnetic FeF2 is observed at ν=0.891 and 2.53 THz (λ=0.337 and 0.119 mm, respectively) by using a pulsed high magnetic field up to 400 kOe. The residual linewidths of the local mode obtained at 4.2 K are respectively 3±0.6 and 1.6±0.6 kOe. These are explained by magnon-phonon interaction at neighboring Fe2+ spin site to which the wave function of the local mode spreads out.
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  • Yukikuni Akishige, T\={o}ru Fukatsu, Masakazu Kobayashi, Etsuro Sawagu ...
    1985 Volume 54 Issue 6 Pages 2323-2328
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Temperature dependence of the dielectric constant and the ac conductivity of Fe3O4 single crystal has been studied below the Verwey point of 122 K in a frequency range from 10 Hz to 10 kHz. Dielectric relaxation phenomena have been found in two temperature ranges: one appears around 30 K–50 K and the other occurs below 20 K. The former has frequency dependence of ac conductivity described by the relation, σac∝ωs (s≤1); the latter is accompanied with the formation of a space-charge layer. Some discussions about the origin of the dielectric relaxation are given.
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  • Teruo Yokoyama, Michihiro Kobayashi
    1985 Volume 54 Issue 6 Pages 2329-2336
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    Pressure dependence of photoluminescence and absorption spectra in AgBr1−xClx (x=1.0, 0.6 and 0.15) is investigated, using a diamond anvil cell with N2 as pressure medium in order to generate good quality of hydrostatic pressure at 1.5 K. Pressure coefficients of self-trapped exciton states in AgCl, AgBr0.4Cl0.6 and that of free exciton state in AgBr0.85Cl0.15 are determined. After initial self-trapped exciton disappears at high pressures, new emission bands are found to appear in AgCl and AgBr0.4Cl0.6. These phenomena are ascribed to pressure-induced phase transition of excitons without accompanying a change of crystal structures.
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  • Hatsuo Hayashi, Satoru Ishizuka, Kazuyoshi Hirakawa
    1985 Volume 54 Issue 6 Pages 2337-2346
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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    Excitable membranes respond irregularly to a periodic stimulation with proper stimulus parameters. Because irregular firing is macroscopic, it seems that irregularity is caused by other factors besides microscopic membrane noise. The responses of the repetitively firing Onchidium pacemaker neuron to a sinusoidal current stimulation were investigated. The irregular responses are classified into three kinds of chaotic oscillation: chaos, intermittency and random alternation. 1/2- and 1/1-harmonic responses bifurcate to chaos via intermittency and random alternation respectively. Harmonic and chaotic responses alternate with each other with increasing frequency of stimulation and with smaller amplitude. Nonlinear factors, threshold and refractory period, are concerned with hyperbolicity of chaotic responses.
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  • Fumiaki Kanô
    1985 Volume 54 Issue 6 Pages 2347-2358
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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    A simple model of small globular proteins is studied for an examination of a diffusion-collision mechanism in a folding and unfolding transition. The model consists of two structural domains. Hydrogen bondings and hydrophobic interactions are considered. The stability of proteins depends on the balance between these noncovalent interactions. The dependences of these interactions on temperature are different. Results obtained here are in good agreement with the experimental data on the temperature dependence of specific heats and kinetic rate constants.
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  • Mototada Kobayashi, Toshiaki Enoki, Hiroo Inokuchi, Mizuka Sano, Akihi ...
    1985 Volume 54 Issue 6 Pages 2359-2360
    Published: June 15, 1985
    Released on J-STAGE: May 29, 2007
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  • Mitsuhiro Nambu
    1985 Volume 54 Issue 6 Pages 2361-2362
    Published: June 15, 1985
    Released on J-STAGE: June 01, 2007
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