Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 62, Issue 12
Displaying 1-50 of 51 articles from this issue
  • Masataka Mizushima
    1993 Volume 62 Issue 12 Pages 4159-4162
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    A binary star system, which has a mutual orbiting rotational speed of ωb, produces a time-dependent anisotropy of space at an observer. The equation of geodesic deviation shows that the resulting anisotropy of space gives rise to a gravitational force between two mirrors, which form an interferometer, and that force is proportional to ωb2 times the anisotropy of space. Because 2π⁄ωb is of the order of days or years, the rigidity kmo of the interferometer, where k is the force constant of a nongravitational force that supports the mirrors and mo is the reduced mass of the mirrors, is much larger than ωb2. The amplitude of the vibrational motion of the interferometer with frequency ωb (in terms of its equilibrium length) is given by (ωb2⁄(km0)) times the anisotropy of space. On the other hand, if we rotate the interferometer with an angular speed of ω of 1 radian/s or more, we can make kmo2, in which case the factor (ωb2⁄(kmo)) disappears, and the rotating interferometer will be useful as a detector of the gravitational waves due to binary star systems.
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  • Norio Kawakami
    1993 Volume 62 Issue 12 Pages 4163-4166
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    An integrable model for SU(ν) electrons with inverse-square interaction is studied for the system with confining harmonic potential. We develop a new description of the spectrum based on the renormalized harmonic oscillators which incorporate interaction effects via the repulsion of energy levels. This approach enables a systematic treatment of the excitation spectrum as well as the ground-state quantities.
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  • Yoshihiro Ishibashi
    1993 Volume 62 Issue 12 Pages 4167-4170
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The wave number (k)-dependence of the average thermodynamic potential density F(k) in the incommensurate phase is discussed, especially in the vicinity of zero wave number. In the case of incommensurate phases such as in NaNO2, (dF⁄dk)k=0=0.
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  • Lianjun Wu, Nobuyoshi Hosoito, Noriaki Nakayama, Teruya Shinjo
    1993 Volume 62 Issue 12 Pages 4171-4173
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    A series of Co/Au(001) superlattices were prepared on GaAs(001) single-crystal substrates using an electron beam deposition method in an ultrahigh vacuum. X-ray diffraction spectra were measured with the scattering vector normal to the film surface, and diffraction peaks from the Co/Au(001) superlattices were observed throughout the entire measured range from low-angle to high-angle. For samples with noninteger numbers of atomic planes in one Co/Au bilayer unit, in the intermediate range (2θ: 20°∼31°) X-ray diffraction peaks indexed from the low angle side did not merge with those satellite peaks indexed from the Co/Au(002) fundamental peak in the high-angle range. This observation indicates a high crystalline quality for Co/Au(001) superlattices with a negligible fluctuation in layer thicknesses and a coherent interface structure.
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  • Shin-ichi Kimura, Yasuhiko Sato, Fumitaka Arai, Kenichi Katoh, Mitsuo ...
    1993 Volume 62 Issue 12 Pages 4174-4177
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    Reflectivity spectra of R3Au3Sb4 (R=La, Ce) polycrystals were measured in the photon energy range from 5 meV to 40 eV at 6, 78 and 297 K. A narrow energy gap was observed for both materials. In La3Au3Sb4, it was seen that the energy gap of about 150 meV is an indirect one. The absorption due to the direct and allowed transition was observed around 0.7 eV. These results are consistent with the calculated band structure. In Ce3Au3Sb4, it was seen that the energy gap of about 70 meV is a direct one. The gap is considered to consist of the occupied 4f state and the unoccupied 5d state.
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  • Eiji Hashimoto, Yoshitake Ueda, Hirofumi Tamura, Takao Kino
    1993 Volume 62 Issue 12 Pages 4178-4181
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Measurements have been made on the residual electrical resistivity in single crystals of high-purity aluminum (RRR\simeq50000) at 4.2 K. The samples were cut from single-crystal plates with {110} surfaces. The axes of the samples were oriented parallel with the principal axes ⟨100⟩, ⟨111⟩ and ⟨110⟩. The results show strong anisotropy, previously not predicted for a normal metal with cubic symmetry. The resistivity increases in the order of the ⟨110⟩, ⟨111⟩ and ⟨100⟩ directions; the value along ⟨100⟩ is significantly larger than those of the other two directions.
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  • Bunjyu Shinozaki, Takasi Kawaguti, Yasunobu Fujimori
    1993 Volume 62 Issue 12 Pages 4182-4185
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The excess conductance σ′ and the magnetoconductance Δσ due to superconducting fluctuations have been measured at temperatures near superconducting transition temperature Tc of aluminum films. The data are analysed in terms of a current theory of the Maki-Thompson (MT) correction of which final expressions for σMT′ and ΔσMT depend on the electron mean free path l but not on the electron phase-relaxation time. Experimental results agree well with the sum of the AL (Aslamazov-Larkin) term and the present MT term. The value of l obtained by a best fit to the data on Δσ is reasonable. However, it increases with increasing temperature.
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  • Meiro Chiba, Kazuhiro Ohara, Yoshitami Ajiro, Takeshi Morimoto
    1993 Volume 62 Issue 12 Pages 4186-4189
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    133Cs NMR experiment has been performed on CsCuCl3 at 4.2 K under the applied magnetic field parallel to the crystal c-axis. An anomalous spectrum has been observed at the critical field of 11.19 T, where the magnetization jump was detected previously. At the critical field, the spectrum is abruptly cut off with no hysteresis for the sweep direction of the magnetic field. The critical field is independent of the operating frequency of the NMR experiment. The result can be explained by the theoretical model of the field-induced transition due to the quantum spin fluctuation in the one-dimensional ferromagnet with S=1⁄2.
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  • Koichi Kindo, Tadashi Shibata, Tetsutaro Inoue, Yoshinori Haga, Takash ...
    1993 Volume 62 Issue 12 Pages 4190-4193
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    A clear de Haas-van Alphen (dHvA) oscillation has been found in LaP doped with 2 atomic percent of Ce under a pulsed field up to 30 Tesla (T) at liquid helium temperature. The oscillation is superimposed on the paramagnetic saturation curve of Ce which does not show the Kondo effect. The Fourier spectrum of the magnetization curves gives an extremal cross-sectional area of the Fermi surface of 0.01 Å−2, which is about a half-value of CeP. The ground state of the Ce atom is investigated by electron spin resonance (ESR) and a nearly isotropic g-value of 1.37 is obtained, in agreement with the theoretical expectation for Γ7, while the g-value of field-cooled CeP is 2.93 which is close to that of Γ8. The discrepancy is discussed using the neutron diffraction data.
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  • Hiroyo Ono, Katsumi Irokawa, Akio Miyazaki, Masaru Komukae, Toshio Osa ...
    1993 Volume 62 Issue 12 Pages 4194-4197
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    Dielectric constants of a NaNH4(SO4)1−x(SeO4)x·2H2O system along the c axis under stress-free and clamped conditions were measured in a temperature range from −210°C to 30°C. Examinations of the pyroelectric current were also carried out. The dielectric constants under stress-free and clamped conditions followed the Curie-Weiss law above the phase transition temperature. It was therefore suggested that the phase transition of the NaNH4(SO4)1−x(SeO4)x·2H2O system is caused predominantly by dielectric instability. A phase diagram of the NaNH4(SO4)1−x(SeO4)x·2H2O system was established from the results of dielectric measurements. It was found that the phase transition temperature of the NaNH4(SO4)1−x(SeO4)x·2H2O system exhibits a minimum value of −200°C at x=0.3. The space group in the ferroelectric phase of NaNH4SO4·2H2O was identified to be P21 from the phase diagram.
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  • Yan Wang, Yasunori Tominaga
    1993 Volume 62 Issue 12 Pages 4198-4201
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Depolarized low-frequency Raman spectra of aqueous solutions of L-ascorbic acid and its isomer D-araboascorbic acid as a function of concentration have been investigated in the frequency region from −250 cm−1 to 250 cm−1 at 30°C. The reduced χ″(\barν) spectrum, which corresponds to the imaginary part of the dynamical susceptibility, due to the dynamical structure of water in aqueous solutions, was analyzed with the superposition of one Cole-Cole-type relaxation mode and two damped harmonic oscillator modes. The effect of L-ascorbic acid on the dynamical structure of water is different from the effect of D-araboascorbic acid.
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  • Kazuhiro Hikami, Miki Wadati
    1993 Volume 62 Issue 12 Pages 4203-4217
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    One-dimensional quantum particle system with SU(ν) spins interacting through inverse square interactions is studied. We reveal algebraic structures of the system: hidden symmetry is the U(ν)≅SU(ν)⊗U(1) current algebra. This is consistent with the fact that the ground state wave function is a solution of the Knizhnik-Zamolodchikov equation. Furthermore we show that the system has a higher symmetry, which is the w1+∞ algebra. With this W algebra we can clarify simultaneously the structures of the Calogero type (1⁄x2-interactions) and Sutherland type (1⁄sin2x-interactions). The Yangian symmetry is briefly discussed.
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  • Tohru Morita
    1993 Volume 62 Issue 12 Pages 4218-4223
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The diagrammatical approach to the exact solution of two-dimensional Ising model, developed for the system with spin 1/2 and 1, is extended to be applicable to the Ising model of spin S greater than 1/2. The exact solution for the system on the square lattice and other lattices with non-crossing interactions is obtained only when the spin is half an odd integer, and the interaction between two spins sj and sk is expressed as −Jjkφj(sjk(sk) in terms of one paramater Jjk and odd functions φj(s) and φk(s) of s satisfying |φj(s)|=|φk(s)|=1 for s=−S, −S+1, …, and S. The exact solution on the honeycomb lattice is obtained for all S, for the cases when the interactions divided by the temperature are expressed in terms of S+1⁄2 or S parameters.
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  • Hideo Shioda, Yohtaro Ueno
    1993 Volume 62 Issue 12 Pages 4224-4232
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    By applying our Monte Carlo twist method we study the Q=6 general clock model with next-nearest-neighbor interactions Vnn in two dimensions (d=2). By estmating the stiffness exponent ψ we find in some range of Vnn an ordered phase of very soft rigidity with ψ close to 0.1 less than d−1 (highest rigidity). This is a counterpart in d=2 of the incompletely-ordered phases (IOPs) with ψ\simeq1.2 already found in the same model in d=3 with Vnn=0 which has two kinds of IOPs (IOP1 and IOP2). Further analyses including the profiles of twisted states indicate that this phase is the IOP2 where a set of three adjacent states are dominant and well mixed. The phase diagram obtained looks very similar to that of the d=3 model except that the IOP1 cannot be found within the range of our study.
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  • Masahiro Nakagawa
    1993 Volume 62 Issue 12 Pages 4233-4239
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    A new method is proposed to evaluate the fractal dimensions of the self-affine data whose power spectra are in accord with a power law. It is on the ground of the logarithmic divergence of the moment of the power spectrum. From a crossover point of the logarithmic behaviour, a critical exponent of the moment can be obtained and related to the fractal dimension. A practical application involves an evaluation of the fractal dimensions of such self-affine data as vowels. As a result of the analyses of the critical behaviour of their moments, those dimensions are found to range over 1.60∼1.71.
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  • Il-Tong Cheon
    1993 Volume 62 Issue 12 Pages 4240-4242
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Effects of the opaqueness of metallic plates have been investigated on the energy shift of the γ-ray absorbed by the nucleus placed between two parallel plates.
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  • Jae-Tack Jeong, Moon-Uhn Kim
    1993 Volume 62 Issue 12 Pages 4243-4254
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Two-dimensional slow viscous flow around a finite vertical plate above a plane wall is investigated based on the Stokes approximation. The flow at infinity is a simple shear flow parallel to the plane wall and/or the plane wall translates parallel to itself. A formal expression for the flow is obtained by solving a three-part Wiener-Hopf equation. By evaluating the formal expression, streamline patterns for typical cases are presented and the flows near the edges of the plate are discussed. Force and moment exerted on the plate are also calculated.
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  • Tawhida S. Basha, A. Abbas
    1993 Volume 62 Issue 12 Pages 4255-4261
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    This paper presents results of cylindrical single Langmuir probe measurements of the electron and ion densities in argon and helium glow discharge plasmas. The gas pressure veries from 5 to 150 Pa. The electron density is determined from the electron probe current at the space potential. The positive ion density is determined from the probe ion saturated current according to Bohm pre-sheath model as well as according to collisional Zakrzewski and Kopiczynski model. At basic pressures of 80 Pa and higher, good agreement is obtained, for both gases, between the electron and ion densities with both models. For basic pressures less than 80 Pa down to 5 Pa, satisfactory agreement between the electron and ion densities is achieved with Zakrzewski and Kopiczynski model where the destruction of the orbital motion of ions in the sheath is still considered.
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  • Gopalraja Praburam, Hiroshi Honda, Masao Sugawa
    1993 Volume 62 Issue 12 Pages 4262-4268
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Suppression of drift waves by the application of externally launched lower hybrid waves has been observed experimentally in an ion-beam plasma system. Suppression is due to ponderomotive force which upshifts the frequency of the drift wave, thus enhancing the Landau damping of electrons. A nonlocal theory incorporating the effect of the finite mode structure is given to explain these experimental results.
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  • Kimitaka Itoh, Sanae-I. Itoh, Atsushi Fukuyama, Masatoshi Yagi, Masafu ...
    1993 Volume 62 Issue 12 Pages 4269-4276
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Theory of the L-mode confinement in toroidal plasmas is developed. The Prandtl number, the ratio between the ion viscosity and the thermal conductivity is obtained for the anomalous transport process which is caused by the self-sustained turbulence in the toroidal plasma. It is found that the Prandtl number is of order unity both for the ballooning mode turbulence in tokamaks and for the interchange mode turbulence in helical system. The influence on the anomalous transport and fluctuation level is evaluated. Hartmann number and magnetic Prandtl number are also discussed.
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  • Shin’ichi Takeda, Masanori Inui, Shigeru Tamaki, Kenji Maruyama, ...
    1993 Volume 62 Issue 12 Pages 4277-4286
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The structure factors of liquid Te at 470°C and 570°C have been newly obtained by X-ray and neutron diffraction. A remarkable and clear difference has been found between X-ray and neutron diffraction results. The ion-electron correlation function and valence electron distribution were evaluated from this difference at two temperatures of 470°C and 570°C. The obtained electron charge distribution function shows two peaks at the distance around 0.80 Å and 1.70 Å just above the melting temperature of 470°C, which corresponds to the distribution of the lone pair electrons and the covalent bonded electrons around a central tellurium ion, respectively. At higher temperature of 570°C, a single peak is observed at the distance around 1.1 Å in the electron charge distribution function.
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  • Kenji Maruyama, Shigeru Tamaki, Shin’ichi Takeda, Masanori Inui
    1993 Volume 62 Issue 12 Pages 4287-4294
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    Using neutron diffraction data for liquid Se and Te, the Reverse Monte Carlo simulations have been performed. For liquid Se at the temperatures of 250°C and 350°C, the obtained structure mainly consists of two-fold coordinated chains, but about 30% of Se atoms have three-fold coordination and many Se3 triangles are observed. For liquid Te a large number of Te atoms have three-fold coordination and the structure of liquid is network-like, which is very different from that of liquid Se.
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  • Masanori Aoki, Shozo Takeno, A. J. Sievers
    1993 Volume 62 Issue 12 Pages 4295-4310
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Stationary anharmonic localized modes with eigenfrequencies appearing in the gap between the optic and acoustic frequency bands are studied for a one-dimensional diatomic lattice with hard or soft quartic anharmonicity. A systematic analytical scheme using the lattice Green’s function method combined with the rotating-wave approximation and its improved version is developed on the one hand, and extensive numerical experiments have been made on the other. The eigenfrequencies and profile functions of anharmonic gap modes are obtained both analytically and numerically. Good quantitative agreement between the theoretical result and the experimental ones is obtained for both of the gap modes due to the hard and soft quartic anharmonicity. It is shown that the spatial localization of the latter is much more pronounced than that of the former.
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  • Akira Onodera, Boris A. Strukov, Alexander A. Belov, Sergei A. Taraski ...
    1993 Volume 62 Issue 12 Pages 4311-4315
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    Thermal and dielectric properties of LaBGeO5, a new ferroelectric with a stillwellite-type structure are investigated. The specific heat, Cp, shows one clear anomaly (ΔS=0.114 R) at 802.5 K. The basic thermodynamic parameters are determined on the basis of the Landau theory. However, an additional hump in Cp was found in a different sample just above Tc. This dependence on samples is confirmed by the measurements of dielectric constants. The appearance of the new intermediate phase may be caused by some impurities or defects. The Rhodes-Wohlfarth plot suggests that the nature of the phase transitions is of the displacive-type.
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  • Masayuki Hasegawa
    1993 Volume 62 Issue 12 Pages 4316-4330
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    A self-consistent theory of freezing which is applicable to systems interacting through long-ranged potentials is presented. It consists of a new formulation of the modified weighted-density approximation (MWDA) based on the idea of the thermodynamic perturbation approach, in which the potential is split into a short-range (reference) part and a long-range part. The MWDA is used separately for the excess free energy of the reference system and the remaining contribution due to the long-range part of the potential. When applied to the one-component plasma, the theory yields results which are in reasonable agreement with the simulation data. It also provides a possible explanation for the reason why the usual approach, in which the solid is mapped onto a single effective liquid, fails for systems with long-ranged potentials.
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  • Shin-ichi Kimura, Fumitaka Arai, Takashi Suzuki, Mikihiko Ikezawa
    1993 Volume 62 Issue 12 Pages 4331-4337
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Reflectivity spectra of a magnetic semiconductor material Gd2S3 (=Gd3−xVxS4, where V denotes vacancy and x=1⁄3) have been measured in the energy range from 2 meV to 40 eV at 9, 20, 77 and 300 K. From the comparison between the optical conductivity and the photoelectron spectra, the energy position and the shape of the occupied and the unoccupied electronic states were obtained. Above 77 K, this material showed a metallic reflectivity spectrum, but an energy gap of about 7 meV opened on the Fermi level below 20 K. The origin of the nonmetal-metal transition was concluded to originate from the creation of a magnetic polaron state.
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  • Norikazu Tomita, Atsushi Ikawa, Hideo Fukutome
    1993 Volume 62 Issue 12 Pages 4338-4351
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Effects of the on-site electron-electron Coulomb interaction U on bond alternation in the one dimensional half filled Hubbard model are studied by the resonating Hartree-Fock method. Two kinds of SDW neutral solitons SA0 and SB0 exist in a bond alternated lattice which are centered at a long bond and a short bond, respectively. SA0 enhances but SB0 suppresses the alternating bond order (ABO) due to bond alternation. Quantum fluctuations in the ground state involve more SA0’s than SB0’s because the former has lower energy than the latter with increasing bond alternation so that they enhance the ABO in the true ground state and consequently the bond alternation. The spin and singlet pair correlation functions show that electrons tend to make singlet pairs on nearest neighbor short bonds even from small U’s and small bond alternations.
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  • Mitsuo Kataoka, Terutaka Goto
    1993 Volume 62 Issue 12 Pages 4352-4363
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The de Haas-van Alphen (dHvA) oscillations of the magnetostrictions and the elastic constants are investigated theoretically. The electron band with orthorhombic symmetry is treated in the effective mass approximation. For ωsτ<<1 with the sound-wave angular frequency ωs and the electron life time τ, Landau orbitals are formed in a deformed metal without affecting local ion motions. In this static approximation to the ion motion, the free energy of the electron-lattice system is calculated as a function of strains. This free energy reveals the acoustic dHvA oscillations and proves that their amplitudes strongly depend on both the direction of an applied magnetic field and the strain mode. It is emphasized that the present acoustic dHvA effect can be a good probe into the electronic properties of metals such as the Fermi surface and the electron-lattice coupling.
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  • Jun Ogura, Tetsuro Saso
    1993 Volume 62 Issue 12 Pages 4364-4372
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Static and dynamic properties of a magnetic impurity in insulators with a small energy gap are investigated by the poor man’s scaling, 1⁄N expansion, the self-consistent perturbation method within the non-crossing approximation (NCA) and the quantum Monte Carlo (QMC) method. It is shown that the ground state of the magnetic impurity changes from the singlet to multiplet when the gap increases, as in the case of the magnetic impurity in a BCS superconductor, although there is a different feature compared to the latter. Critical value of the gap Ec is found to be EcTK=2.0 by 1⁄N expansion and NCA, while EcTK≈0.4∼0.9 by QMC, where TK denotes the Kondo temperature. It is found by the poor man’s scaling that Ec is enhanced (reduced) by the enhanced (rounded) gap-edge.
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  • Toshikazu Nakamura, Tokutaro Komatsu, Gunzi Saito, Toshihito Osada, Se ...
    1993 Volume 62 Issue 12 Pages 4373-4385
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The electrical resistivity measurements for the novel organic superconductor κ-(BEDT–TTF)2Cu(CN)[N(CN)2] (Tc=11.2 K) [BEDT–TTF represents bis (ethylenedithiolo)tetrathiafulvalene] under pressure or in high magnetic field were studied. Several physical parameters, such as the superconducting transition temperature (Tc), the depressibility of Tc with pressure (−dTc⁄dP), the residual resistance ratio (RRR), the upper critical field (HC2), and the effective Ginzburg-Landau mass anisotropy between perpendicular and parallel to the conducting plane (m⁄⁄m), are determined. They are discussed in comparison with those of other κ-type organic superconductors with Tc above 10 K; κ-(BEDT–TTF)2Cu(NCS)2 and κ-(BEDT–TTF)2Cu[N(CN)2]Br. A simple relation was observed between these parameters (Tc, −dTc⁄dP and RRR) and the dimensionality of the electronic structures of these superconductors.
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  • Keisuke Nakazawa, Kazuya Suzuki, Toshiaki Enoki, Ko Sugihara, Seiji Mi ...
    1993 Volume 62 Issue 12 Pages 4386-4392
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The c-axis resistivity ρc which indicates a metallic temperature dependence was measured in stage 1 and 2 potassium-hydrogen-graphite intercalation compounds (KH-GICs) in the temperature range of 1.5–300 K below 15 kbar. The pressure effect on ρc suggests a hopping conduction process for the c-axis transport mechanism, which is governed by the number of conduction paths and the transfer integral across the intercalate layer. The magnitudes of ρc in stage 1 and stage 2 compounds are mainly dominated by the number of their impurity and defects concentrations in the conduction paths.
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  • Koji Kobayashi, Ko Sugihara, Hisashi Oshima, Takuro Tsuzuku
    1993 Volume 62 Issue 12 Pages 4393-4397
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    Thermoelectric power in c-direction (Sc) of highly oriented pyrolytic graphite (HOPG) exhibits a sharp negative dip around 20–30 K. This anomaly is ascribed to the phonon drag thermoelectric power (Sp) related to the out-of-plane vibration and Sp is calculated in close relation to the mechanism of c-axis conduction. Major contribution to Sc comes from Sp which can provide a qualitative explanation of the observed results.
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  • Makoto Matsui, Wataru Sasaki
    1993 Volume 62 Issue 12 Pages 4398-4406
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Annealing processes have been studied in thermal-neutron irradiated, heavily arsenic-doped, n-type germanium crystals with initial donor concentrations of 3.24×1018, 3.32×1018 and 5.20×1018 cm−3 by measuring the resistivity and the Hall effect after isochronal annealings. The concentration of conduction electrons, the resistivity and the Hall mobility recover stepwise at essentially the same annealing temperatures for the three quantities and different samples. In the Hall mobility recovery, “reverse” annealing is observed over an annealing-temperature range from 250 to 320°C for all samples, in contrast to monotonic recovery of the carrier concentration and the resistivity. The reverse annealing is interpreted as being due to dissociation of vacancy-arsenic complexes formed in the preceding annealing process.
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  • Hideki Futagawa, Noboru Miura, Koji Yamada, Norihiko Kamata, Akira Kow ...
    1993 Volume 62 Issue 12 Pages 4407-4413
    Published: December 15, 1993
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    We have observed a novel feature in the hot-electron magnetophonon resonance in n-type germanium at pulsed high magnetic fields up to 40 T. In the longitudinal magnetophonon resonance, the resonance peaks appear as either maxima or minima depending on the difference in the effective mass between the initial and final states of the intervalley scattering by phonons. The results are interpreted in terms of the mobility change of conduction electrons at the resonance.
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  • Takashi Hotta
    1993 Volume 62 Issue 12 Pages 4414-4425
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The origin of superconductivity in cuprate oxide systems is studied from the first principle starting with the d-p model Hamiltonian. We derive the Dyson-Gor’kov equations which include the second order terms with respect to Coulomb repulsion U between d-electrons both in normal and anomalous self-energy parts, and solve them completely in due consideration of full momentum and energy structures in the equations. We obtain the superconducting transition temperature Tc by treating both the attractive interaction and the damping effect on an equal footing. As a result, it is shown that d-wave superconductivity is possible under a suitable condition, though Tc is suppressed by the damping effect. The possibility of obtaining high Tc by including higher order terms in U is discussed in connection with the experimental results on Tl-systems.
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  • Hiroaki Kadowaki, Toshikazu Ekino, Hiroshi Iwasaki, Toshiro Takabatake ...
    1993 Volume 62 Issue 12 Pages 4426-4437
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Successive phase transitions in the Kondo compound CePtSn are studied by neutron scattering experiments on a single-crystalline sample. Antiferromagnetic phase transitions are observed at TN=6.2 K and TM=3.8 K, which are second and first order transitions, respectively, in accord with the previous specific heat measurement. The magnetic structure is a single-Q type Snν=aνeik·Rn+aν*e−ik·Rn with incommensurate modulation vectors k=0.466b* and 0.418b* in the low (T<TM) and intermediate (TN<T<TM) temperature phases, respectively. The polarization vectors aν cannot uniquely be determined from scattering intensities, and thus those which reproduce the intensities are selected using a maximum entropy method. In the low-temperature phase, the polarization vectors have a, b and c components, and the root mean square of the moment is mrms=0.84±0.08 μB (mrmsa=0.72, mrmsb=0.31, mrmsc=0.29 μB) at T=2 K. In the intermediate-temperature phase, the polarization vectors have a and c components, and mrms=0.60±0.06 μB (mrmsa=0.56, mrmsc=0.22 μB) at T=4.8 K.
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  • Kenji Nakajima, Kazuyoshi Yamada, Syoichi Hosoya, Tomoya Omata, Yasuo ...
    1993 Volume 62 Issue 12 Pages 4438-4448
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Inelastic neutron magnetic scattering experiments were performed from the well characterized single crystal of La2NiO4.00 (TN=328 K) to study the spin-wave excitations in this system. The large energy gaps are observed at the two dimensional zone center, namely 15.7 meV for the out-of-plane mode, and 4.1 meV or 7.9 meV below or above 70 K for the in-plane mode respectively. Combined with the higher energy scans carried out by the spallation neutron source, the whole dispersion relation was determined, which follows a linear spin-wave model. It provides the microscopic parameters of nearest neighbor exchange interactions in plane, two anisotropy energies corresponding to the out-of-plane and in-plane modes, respectively, 28.7±0.7 meV, 1.26±0.12 meV and 0.10±0.02 meV at 10 K. The scattering intensities also nicely follow the linear spin-wave model at the lowest temperature. The results are discussed with the previous experiments on the spin dynamics of La2CuO4.
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  • Jun-ichi Igarashi
    1993 Volume 62 Issue 12 Pages 4449-4457
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    We calculate the spin-wave dispersion and the sublattice magnetization up to second order in the 1⁄S expansion for the antiferromagnetic Heisenberg model with nearest-neighbor (J1) and second-neighbor (J2) couplings on a square lattice. The corrections to the linear spin-wave theory for the spin-wave dispersion and the sublattice magnetization grow large when the frustration increases. The expansion seems to converge asymptotically well for J2J1<0.35, leading to quantitative estimates for both quantities. The corrections are positive for J2J1<0.4, making the Néel ordered state more stable than what the linear spin-wave theory predicts. When J2J1 exceeds 0.4, the second-order corrections grow very large with negative sign.
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  • Shingo Aoyama
    1993 Volume 62 Issue 12 Pages 4458-4466
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Electrical resistivity is calculated on the basis of the effective nuclear Hamiltonian above and below the nuclear ordering temperature Tc. The conduction electrons are scattered by the nuclear spins mediated by the f-electrons through the s-f exchange interaction and the hyperfine interaction. By the short range order, the resistivity increases or decreases from the value of the non-interacting nuclear spin system depending on the sign of the RKKY interaction and the size of kF. In low temperatures the resistivity is calculated by the spin wave approximation. The T-dependence reflects the crystal field anisotropy through the dispersion relation of the spin wave. It is shown also that the aspherical Coulomb interaction, which works sometimes to the resistivity at high temperatures, is not effective in this low temperature region.
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  • Hitoshi Ohta, Seisaku Imagawa, Mitsuhiro Motokawa, Eiji Kita
    1993 Volume 62 Issue 12 Pages 4467-4473
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    The dependences of the resonance fields and the FMR absorption intensities of Fe/MgO multilayered films on the thickness of the Fe layer have been obtained by the submillimeter wave FMR using the pulsed magnetic field up to 15 T at 4.2 K. The magnetic anisotropy of each film, which is determined by the frequency dependence of the FMR with the aid of the results of the magnetization measurements, can explain the angular dependence of the FMR completely. The dependence of FMR absorption intensity on the thickness of Fe layer, however, turned out to be rather different from the results of the magnetization measurements.
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  • Mamoru Mekata, Nariyasu Yaguchi, Takeo Takagi, Tsukasa Sugino, Setsuo ...
    1993 Volume 62 Issue 12 Pages 4474-4487
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Magnetic ordering in a rhombohedrally stacked triangular lattice antiferromagnet, CuFeO2 was investigated on powder and single crystals by measurements of neutron diffraction, magnetic susceptibility, Mössbauer effect together with Monte Carlo simulations. CuFeO2 was found to exhibit transitions at TN1=16±0.5 K and TN2=11±0.5 K. The low temperature phase has an orthorhombic magnetic unit cell with collinear moments along the c-axis, whereas the intermediate temperature phase is a partially disordered phase with a monoclinic magnetic unit cell where 1/5 of moments remain paramagnetic. The Monte Carlo simulations for the Ising spin tiangular lattice antiferromagnet can reproduce the observed successive transition in the case of the exchange parameters 4J3<2J2J1<0. This combination of exchange parameters gives an account for the stability of the collinear magnetic structure in CuFeO2.
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  • Hiroko Aruga Katori, Atsuko Ito
    1993 Volume 62 Issue 12 Pages 4488-4502
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Systematic studies of a random mixture FexMn1−xTiO3 with competing exchange interactions have been made by low-field dc-magnetization measurements. Typical behavior characterizing a spin-glass transition is observed in the samples with intermediate Fe concentrations. The samples with Fe- and Mn-rich concentrations undergo the transition to the antiferromagnetic phase, and the samples with certain concentrations reenter into the reentrant spin-glass phase at low temperatures. From these results, the concentration versus temperature phase diagram is determined. In FexMn1−xTiO3 the characteristic properties of the spin-glass and reentrant spin-glass appear strongly, that is because FexMn1−xTiO3 is a magnetically condensed system with strong frustration. The magnetic properties observed in the antiferromagnetic phase of this system have clarified that the spin configuration is quite different from those in ordinary antiferromagnets.
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  • Mitsuo Wada, Yasuharu Yamashita, Akikatsu Sawada, Yoshihiro Ishibashi
    1993 Volume 62 Issue 12 Pages 4503-4510
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The dielectric dispersion in the ferroelectric Li2−xNaxGe4O9 (x≈1) single crystals has been measured in the frequency range from 120 Hz to 10 MHz around the transition temperature TC=109 K. The Debye-type dispersion was observed in the MHz region. The relaxation time increases abruptly as TC is approached from above, which shows the critical slowing-down of dielectric response. The relaxation time is 1.5×10−8 sec at 0.5 K above TC. The softening of the optical phonon has not been observed by Raman scattering measurement. The ferroelectric phase transition of Li2−xNaxGe4O9 (x≈1) is the typical order-disorder one. The origin of the polydispersive nature and the sample dependence of the relaxation time are discussed.
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  • Kazuo Gesi
    1993 Volume 62 Issue 12 Pages 4511-4515
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The effect of hydrostatic pressure on the phase transitions in the deuterated crystal Ca2Ba(C2D5COO)6 (DDBP) has been studied by dielectric measurements in a temperature and pressure range of 170 K\lesssimT\lesssim360 K and p\lesssim650 MPa. The resultant p-T diagram is compared with that of the normal compound Ca2Ba(C2H5COO)6 (DBP). A marked deuteration effect is seen for the pressure-induced ferroelectric Curie temperature (the IV–V boundary); the deuteration causes almost parallel depress of the boundary by about 10 K. The deuteration effects are discussed in connection with those of Ca2Sr(C2H5COO)6 and Ca2Pb(C2H5COO)6.
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  • Vadim. F. Aguekian, Yu A. Stepanov, Ichirou Akai, Tsutomu Karasawa, Te ...
    1993 Volume 62 Issue 12 Pages 4516-4521
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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    The exciton spectra of SnO2 single crystals with the low and high concentrations of the oxygen vacancies (OV) are investigated. The series of luminescence lines adjacent to the lowest free exciton states (the excitons localized by the isolated OV and OV clusters) increases superlinearly with the optical excitation level. It is shown that the luminescence spectra of SnO2 can be described as the zero-phonon and one LO-phonon assisted anihilation of the free and localized excitons. The shape of LO-phonon replicas of the free exciton luminescence corresponds to Maxwellian distribution of the excitons which have the effective temperature significantly higher than the lattice temperature in the case of pulse excitation level 106–107 W/cm2.
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  • Z. J. Li, K. L. Yao, Z. An, Z. G. Li
    1993 Volume 62 Issue 12 Pages 4522-4526
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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    Seven localized vibrational modes have been found for the soliton in trans-(CH)x for a two-dimensional extension of the SSH model that includes the bond-bending term, the Hubbard interaction and the electrostatic pinning. Three of them are infrared active, and they can be used to interpret the three observed infrared absorption lines at 500 cm−1 (or 900 cm−1), 1260 cm−1 and 1370 cm−1.
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  • Biswanath Rath, K. Patnaik
    1993 Volume 62 Issue 12 Pages 4527-4528
    Published: December 15, 1993
    Released on J-STAGE: June 01, 2007
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  • Riki Kawashima, Takayoshi Saitoh, Hiroshi Isoda
    1993 Volume 62 Issue 12 Pages 4529-4530
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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  • Yousuke Tanaka, Kazuyuki Watanabe
    1993 Volume 62 Issue 12 Pages 4531-4532
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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  • Mitsuru Sugisaki, Masaru Eguchi, Osamu Arimoto, Kaizo Nakamura, Makoto ...
    1993 Volume 62 Issue 12 Pages 4533-4534
    Published: December 15, 1993
    Released on J-STAGE: May 29, 2007
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