Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 59, Issue 8
Displaying 1-50 of 59 articles from this issue
  • Shigeru Sasabe
    1990 Volume 59 Issue 8 Pages 2607-2609
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    The effect of nonradiative bound energy is investigated on the quantum charged harmonic oscillator. We find that the bound energy does not prevent the motion of the oscillator; the motion is undamped, and is still harmonic.
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  • Koh Wada, Naotoshi Watanabe
    1990 Volume 59 Issue 8 Pages 2610-2613
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    The critical exponent ν of correlation length is calculated on the basis of the coherent anomaly method (CAM) by using the pair, the cactus-square and the square approximations of the cluster variation method (CVM) in the D (≥2)-dimensional cubic lattice of the Ising model. These simple analytical approximations give good values of critical exponent ν and critical temperature in the two- and three-dimensional lattices. However, further consideration is needed to determine a critical dimension in the D-dimensional Ising model by the CAM.
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  • Toshikazu Kurihara, Shoichiro Tanigawa
    1990 Volume 59 Issue 8 Pages 2614-2616
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    The result of thermal equilibrium measurements of aluminum and aluminum dilute alloys was reported. We applied the high precision measurements of the Doppler broadened lineshapes of annihilation radiations to pure aluminum and aluminum based dilute alloys (Al-0.50 at.%Li and Al-0.50 at.%Mg). A typical temperature dependence of the lineshape parameter was observed in pure aluminum. On the other hand, a drastic increase in the lineshape parameter near melting point was observed in the dilute alloys, contrary to the result reported by Hashimoto et al. (J. Phys. F 14 (1984) 879).
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  • Hidetoshi Fukuyama, Kazuhiro Kuboki
    1990 Volume 59 Issue 8 Pages 2617-2620
    Published: August 15, 1990
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    The effect of gauge fields representing the local constraints and the phase fluctuation of the bond order parameters are investigated for the fluxless state which was recently proposed by Nagaosa and Lee as a possible model for high Tc oxides. If the system is clean, both spin susceptibility and NMR rate, (T1T)−1, are found to be essentially independent of temperature, whereas in a dirty case, the latter increases in proportion to the inverse temperature.
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  • Yukio Okwamoto, Shu-ichi Nagasawa
    1990 Volume 59 Issue 8 Pages 2621-2623
    Published: August 15, 1990
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    A one-body problem on the triangular lattice is solved in the presence of a fictitious magnetic field which produces a quarter of a flux quantum through each triangle. Then it is shown explicitly that the fractional quantum Hall wave function for a ground state of the s=1⁄2 triangular lattice antiferromagnet is equivalent to a variational singlet wave function written by a pair of determinants which are made out of eigenfunctions of the one-body problem.
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  • Takehiko Mori, Hiroo Inokuchi, Hatsumi Mori, Shoji Tanaka, Masashi Osh ...
    1990 Volume 59 Issue 8 Pages 2624-2626
    Published: August 15, 1990
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    Anisotropy of thermoelectric power of a series of organic metals (BEDT–TTF)2MHg(SCN)4 [M=K, Rb, and NH4] is measured and compared with a simulation based on the two-dimensional tight-binding band calculation.
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  • Daijiro Yoshioka
    1990 Volume 59 Issue 8 Pages 2627-2630
    Published: August 15, 1990
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    Pressure dependence of the transition temperature of the high-Tc Cu-oxide superconductors strongly suggests the importance of the apical oxygen. By an assumption that the distance between the CuO2 plane and the apical oxygen governs the transition temperature, displacement of the apical oxygen below Tc is verified through the phenomenological Ginzburg-Landau theory. The magnitude of the displacement is estimated, and compared with various experiments.
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  • Hideki Yoshizawa, Hiroshi Mori, Kazuma Hirota, Masayasu Ishikawa
    1990 Volume 59 Issue 8 Pages 2631-2634
    Published: August 15, 1990
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    We have demonstrated that a two-dimensional triangular lattice antiferromagnet with spin=1/2 LiNiO2 reveals ferromagnetic short-range spin correlations in forward scattering below TN1∼240 K, unlike other two-dimensional trianglar lattice antiferromagnets. The intensity of diffuse scattering in the forward direction appears below TN1, and monotonically increases as the temperature is lowered, then shows a sharp divergence at TN2∼35 K. The present results suggest that a frozen spin pattern with the ferromagnetic short-range correlation similar to the spin glass phase is realized at the low-temperature phase below TN2. In contrast, no appreciable intensity was detected around the (1/3, 1/3, n) positions, being consistent with early studies.
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  • Tomobumi Mishina, Fumio Sasaki, Yasuaki Masumoto
    1990 Volume 59 Issue 8 Pages 2635-2638
    Published: August 15, 1990
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    We have observed microsecond decay of bleaching and anomalous induced absorption in staggered alignment type-II AlxGa1−xAs/AlAs ternary alloy multiple-quantum-well structures. In a microsecond time scale, the time evolution of bleaching was almost the same as that of type-II photoluminescence. The induced absorption, which occurs immediately after the photoexcitation, was observed at the low-energy tail of the exciton. These results indicate an interlayer Γ-X scattering process and suggest the resultant spatial redistribution of carriers.
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  • Kozo Okada, Yasuhiro Seino, Akio Kotani
    1990 Volume 59 Issue 8 Pages 2639-2642
    Published: August 15, 1990
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    The role of the Cu 4s band in the Cu 2p-XPS of Nd2−xCexCuO4 is investigated on the basis of the impurity Anderson model. The model consists of the impurity Cu 3d shell and the conduction and valence bands formed from the O 2p and Cu 4s bands under the tight-binding approximation. Because of the symmetry of the crystal, the 3d states couple weakly to the Cu 4s band so that the effect of the 4s band on the Cu 2p-XPS is very small in general. However, in the case where the 4s band is lower by a few eV in energy than that estimated by the first-principle calculation, the 4s state is important in the electron doping process in Nd2−xCexCuO4 because the doped electron enters this state.
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  • Yasunori Yamazaki, Kenro Kuroki, Ken-Ichiro Komaki, Lars H. Andersen, ...
    1990 Volume 59 Issue 8 Pages 2643-2646
    Published: August 15, 1990
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    The spectrta of electrons emitted in the forward direction from antiproton and proton bombardments on carbon foils have been studied for projectile energies from 500 to 750 keV. Our main observation is that at the electron energy where the well-known convoy peak is observed for proton impact, the spectrum for equivelocity antiprotons is smooth, showing no indication of a deep anticusp. However, around 50 eV below the electron energy where the cusp is observed for proton impact, we have observed a small peak for antiproton impact. The energy and the relative intensity of the bump are found to be consistent with those predicted for electrons released from a wake-riding state.
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  • Yoshiko Okada, Shinsuke Watanabe, Hiroshi Tanaca
    1990 Volume 59 Issue 8 Pages 2647-2658
    Published: August 15, 1990
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    The behaviour of solitary wave has been studied numerically in periodic Toda lattice which has alternate Toda potentials with different parameters. In the numerical calculation, due to deviations from the ideal Toda lattice, the solitary wave decreases in propagation, trailing ripple oscillation behind it. Yet, the stability of the waves depends on the lattice parameters. A narrow solitary wave compared with the lattice constant can propagate stably in the periodic lattice under our special condition. The validity of the K-dV approximation is examined concerning the velocity and width of a small amplitude solitary wave. The duality of nonlinear lattice is also discussed.
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  • Kazuhiro Fukushima, Tomoji Yamada, Taichi Yazaki, Hirokazu Fujisaka
    1990 Volume 59 Issue 8 Pages 2659-2666
    Published: August 15, 1990
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    A new type of intermittency associated with the transition from uniform to nonuniform chaos in a coupled electronic circuit is studied by means of the fluctuation spectrum theory. The time series are constructed by taking the n-th power of original experimental data obtained near the intermittent transition point. The intermittent behavior is enhanced as the power n is increased. Two types of scaling laws are found for the fluctuation spectra σ(α)’s.
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  • Junji Suzuki, Yasuhiro Akutsu, Miki Wadati
    1990 Volume 59 Issue 8 Pages 2667-2680
    Published: August 15, 1990
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    Presented is a new approach to the study of one dimensional quantum spin systems at finite temperature. The approach is based upon a general structure of solvable models; the Yang-Baxter equation and the Bethe ansatz equation, and in addition the evaluation of finite size corrections. Provided that the ground state is constructed by the Bethe ansatz method, exact low temperature expansions of physical quantities are given without further assumption.
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  • Sumiyoshi Fujiki, Makoto Katori, Masuo Suzuki
    1990 Volume 59 Issue 8 Pages 2681-2687
    Published: August 15, 1990
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    The coherent-anomaly scaling property of the susceptibility for the Ising model is investigated using the Tanoji (a Chinese character which means a rice field) and cube cluster-approximations in the cluster-variation method on the square and simple cubic lattices, respectively. Estimates of the critical temperature and critical exponent are improved considerably by the inclusion of these high-level cluster-variation approximations in the coherent-anomaly extrapolation. It is also found that the dimensionality of the basic cluster is sensitive to the evaluation of critical exponents in higher dimensions.
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  • Tôru Sakai, Minoru Takahashi
    1990 Volume 59 Issue 8 Pages 2688-2693
    Published: August 15, 1990
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    The S=1 XXZ spin chain is studied by the finite-size scaling and phenomenological renormalization-group technique up to N=16. It is found that a two-dimensional Ising-model-type transition exists at λ=1.188±0.007, and a Kosterlitz-Thouless-type transition exists at λ=−0.01±0.03. It agrees with Haldane’s conjecture completely.
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  • Arvind Sharma, S. D. Sharma
    1990 Volume 59 Issue 8 Pages 2694-2699
    Published: August 15, 1990
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    In case of odd-odd nuclei, near magic numbers, there are found inverted sequences as well as few rotational members. In order to explain the unique feature of the spectra of odd-odd nuclei, we have applied modified form of rotational-vibrational model with two parameters A and B. It is found that level orders in inverted as well as in rotational sequences are very well reproduced on the basis of this model. In case of inverted spin sequences, the sign of B is found to be positive. The ratio of BA is ≈10−2 as compared to its value of the order of 10−3 in case of even-even & odd—A nuclei. We infer that pair correlations are responsible for these invertions. The simple model applied here worked well to predict these inverted spectra.
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  • Masanori Wakasugi, Takayoshi Horiguchi, Wei Guo Jin, Hidefumi Sakata, ...
    1990 Volume 59 Issue 8 Pages 2700-2713
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    Isotope shifts and hyperfine structures in 28 optical transitions for 28 stable isotopes of Nd, Sm, Gd and Dy were measured by means of the atomic-beam laser-spectroscopy. The nuclear parameter λ was obtained from the isotope shift measurement for all the stable nuclei with the improved accuracy. The λ values were analyzed by using the Fermi distribution for the nuclear charge density. As a result, the diffuseness at the nuclear surface or the hollow depth near the center of nucleus in the charge distribution depends on the neutron number. The values of δ⟨r2⟩ and also δ⟨r4⟩ were determined. It is shown that λ is a good probe into the systematic change of the nuclear charge distribution.
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  • Yukio Kaneda
    1990 Volume 59 Issue 8 Pages 2714-2726
    Published: August 15, 1990
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    The force on a Brownian particle moving at a small but finite velocity in an incompressible fluid is studied on the basis of equations governing fluctuating hydrodynamics. A nonlinear Langevin equation for a spherical Brownian particle with an explicit fluctuation-dissipation relation depending on the motion of the particle is derived.
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  • Mitsunori Fukutoku, Nobuaki Ikuta
    1990 Volume 59 Issue 8 Pages 2727-2741
    Published: August 15, 1990
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    Detailed flight behaviour of electrons in a Reid ramp model gas under DC electric field is calculated by the flight time integral (FTI) method. The results are very accurate and are in good agreement with those of previous papers. A new function to judge the convergence to equilibrium distribution is presented. The transport coefficients derived from transport functions, energy and momentum balance equations and the validity of the formula commonly appearing in the two-term analysis are discussed.
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  • Kazuhiro Urata
    1990 Volume 59 Issue 8 Pages 2742-2757
    Published: August 15, 1990
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    The influence of the unperturbed shear flow on the nonlinear evolution of the tearing mode is studied. In the case of single helicity, the shear flow activates the unstable mode which finally saturates to a rigid rotor state. In the case of multiple helicity, a variety of flow patterns is created depending on parameters, and always forms the current bubble soon after the collapse of the 3/2 magnetic island.
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  • Jiro Todoroki
    1990 Volume 59 Issue 8 Pages 2758-2775
    Published: August 15, 1990
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    Analytic expression for the longitudinal adiabatic invariant is derived for general magnetic configuration. The orbit loss is evaluated to determine the outermost loss-free surface. Geometrical factor of the neoclassical transport coefficients in 1⁄ν regime in helical torus is calculated by using the longitudinal adiabatic invariant. The dependence of the particle confinement upon the geometrical parameter is investigated; and the improvement by the inward shift of the plasma is quantitatively clarified.
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  • B. Bhattacharyya, Tsuguhiro Watanabe, Kyoji Nishikawa
    1990 Volume 59 Issue 8 Pages 2776-2781
    Published: August 15, 1990
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    General expressions for the ponderomotive force as a second-order average force acting on a single charged particle is derived in the form of a potential force. The result is valid for arbitrary spatial structure of the ambient static magnetic field. Sum of the resulting drift flux and the second-order magnetic flux due to the induced magnetic moments of the particles is found to agree with the second-order averaged flux calculated by the cold fluid model.
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  • Yukiharu Ohsawa
    1990 Volume 59 Issue 8 Pages 2782-2789
    Published: August 15, 1990
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    Ion orbits in a large-amplitude magnetosonic wave are studied numerically and analytically. The orbits are classified into three basic types. In the first type, ions pass through the wave without reflection and do not gain much energy. In the second type, they are reflected once and are accelerated in the direction of the wave normal. In the third type, they are reflected several times and are accelerated in the direction parallel to the wave front. Conditions for these types of reflection are discussed and the energies of accelerated ions are evaluated.
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  • Yukihiro Shimoi, Hideo Fukutome
    1990 Volume 59 Issue 8 Pages 2790-2803
    Published: August 15, 1990
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    The crystal structure of As2S3 has degeneracies of two kinds as shown in a previous paper. By inserting locally other possible degenerate structures to a ground state, valence alternation pairs (VAP) can be generated as soliton like defects. The degeneracies concerning the arrangement of lone pairs and the directions of interhelix covalent bonds lead, respectively, to the generations of the VAPs of C1–C3 and P2–P4 types. We calculate the structures and formation energies of the VAP’s by using a valence force field model. The formation energy of a VAP is large in multilayered crystal but much reduced in a single layer suggesting its easy production in amorphous regions. Production of VAP’s induces changes of the layer structure in a surrounding region.
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  • Yukio Noda, Shingo Uchiyama, Koumei Kafuku, Hirofumi Kasatani, Hikaru ...
    1990 Volume 59 Issue 8 Pages 2804-2810
    Published: August 15, 1990
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    Structure analysis of K3H(SO4)2 was performed by X-ray diffraction experiments in order to study the hydrogen bond character in connection with the geometrical isotope effect. Crystal data at room temperature were obtained as a=9.777(1)Å, b=5.674(1)Å, c=14.667(4)Å, β=102.97(2)° and the space group A2⁄a, Z=4. The hydrogen bond length ROO determined from the positional parameters was 2.493(1)Å which was close to but still longer than the so called critical bond length rc. The electron density of split hydrogen atoms was observed on a differential Fourier map. It is concluded that the hydrogen atoms take the disordered state at room temperature and the distance between hydrogen atoms RHH is approximately 0.65 Å. The possibilities for the existence both of the low temperature phase and the high temperature prototype phase are discussed.
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  • Jun-ichi Igarashi
    1990 Volume 59 Issue 8 Pages 2811-2819
    Published: August 15, 1990
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    A mechanism of crystal distortion under high pressure is discussed in solid normal hydrogen. The strong interaction between the lattice vibration and the degenerate rotational states on orthohydrogens is treated in a form similar to the cooperative Jahn-Teller effect. The crystal field due to the local distortion can be very large under high pressure, leading to continuous decrease of the axial ratio, ca, from its ideal value of the hcp structure with increasing pressure at room temperature, in agreement with the recent experiments. Isotope effects are also discussed. The first order transition of the distortion is predicted as a function of temperature.
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  • Hisao Jichu, Tamifusa Matsuura, Yoshihiro Kuroda
    1990 Volume 59 Issue 8 Pages 2820-2830
    Published: August 15, 1990
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    The electronic states in the CuO2-layer have been studied by using the p-d model with the help of the auxiliary boson method for treating the local electronic correlation properly. What have been found are: at sufficiently low temperature the electronic states form coherent bands, whose width and intensity are strongly depending upon number of doped carriers (more significantly for holes than electrons) and the p-d charge transfer energy. In particular, when the number of doped-holes nh is small, a new band form around the Fermi level inside the energy gap and its width and intensity are proportional to nh. Even then the Fermi surface is still determined by the total number of unpaired electrons which are mainly of the localized d-electrons.
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  • Yoshio Kuramoto, Kazumasa Miyake
    1990 Volume 59 Issue 8 Pages 2831-2840
    Published: August 15, 1990
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    A quantum mechanical phenomenology for heavy-fermion systems is formulated. The effective Lagrangian for low-energy excitations contains a localized spin-fluctuation part which is coupled with an itinerant fermion part. Each part represents the dual nature of strongly correlated f electrons. The coupling parameter is fixed by comparison with the Fermi-liquid theory for the Anderson model. The comparison also fixes the localized spin-fluctuation spectrum. As an advantage over the Fermi-liquid description the present model takes into account the RKKY interaction and non-linear effects of spin polarization. A formula for the magnetic equation of state is derived which is applicable to the metamagnetism and weak antiferromagnetism in heavy-fermion systems.
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  • Shugo Suzuki, Yutaka Toyozawa
    1990 Volume 59 Issue 8 Pages 2841-2847
    Published: August 15, 1990
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    The ground-state properties of the low-density electron system with the short-range electron-phonon interaction is investigated theoretically in connection with the self-trapping of an electron. The energy change of the system due to lattice distortions is calculated with the use of Fumi’s theorem and the coherent potential approximation. It is shown that the itinerant electrons and the self-trapped electrons coexist in a certain range of the parameters.
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  • Izuru Umehara, Yoshiko Kurosawa, Nobuyuki Nagai, Makoto Kikuchi, Kazuh ...
    1990 Volume 59 Issue 8 Pages 2848-2855
    Published: August 15, 1990
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    The magnetoresistance and the de Haas-van Alphen (dHvA) effect in CeSn3 have been measured in the field up to 150 kOe and at temperature down to 0.45 K. The magnetoresistance does not show a tendency to saturate in all field directions. This result claims that CeSn3 is a compensated metal with an equal carrier concentration of electrons and holes, and electron and hole Fermi surfaces possess no open orbits. In contrast to an uncompensated metal LaSn3, the 4f electrons in CeSn3 become itinerant electrons. This is consistent with the dHvA data which are almost explained by the modified Fermi surface model based on the result of band calculation where the 4f electrons are treated the same as the usual s, p, d conduction electrons.
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  • Ry\={o}en Shirasaki, Yasushi Wada
    1990 Volume 59 Issue 8 Pages 2856-2864
    Published: August 15, 1990
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    New electronic localized states are analytically determined around a soliton. One of them has the energy lower than the bottom of the valence band and the other higher than the top of the conduction band. They are induced by the acoustic component of the order parameter in the first order Hamiltonian with respect to the ratio between the lattice constant and the soliton width. Usual perturbation procedure is vastly modified to obtain the states. Their energies agree fairly well with numerical simulation works, which have first indicated these levels.
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  • Ko Sugihara, Koji Kobayashi, Hisashi Oshima
    1990 Volume 59 Issue 8 Pages 2865-2874
    Published: August 15, 1990
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    Thermoelectric power (TEP) of first-stage non-magnetic graphite acceptor intercalation compounds drops rapidly to a negligibly small value below 7 K. In contrast to the non-magnetic GICs, the magnetic compounds such as first-stage FeCl3- and CoCl2-GICs exhibit much larger TEP, which is expected to be due to the magnon drag effect. This prediction is confirmed theoretically in this article. The present calculation is carried out for CoCl2-GIC, since its magnetic properties have been extensively studied. The dispersion relation for the long wavelength magnons is phonon-like. This is due to the 2D-character of the spin system. By solving the coupled Boltzmann equation for carriers and magnons the magnon drag TEP is calculated and the calculated temperature dependence is proportional to T at low temperatures, which is consistent with the measurement. The calculated value has the same order of magnitude as the observed one.
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  • Ko Sugihara, Akio Ono, Yoshihiro Hishiyama
    1990 Volume 59 Issue 8 Pages 2875-2883
    Published: August 15, 1990
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    The magnetic field dependence of the thermomagnetic tensor components βxx and βyx for a high quality kish graphite specimen is studied in the temperature range 1.5–15 K with application of the field up to 0.1 T. β is a more fundamental quantity than thermoelectric power. βxx shows a negative dip at 3.8 K and a sharp peak at 11 K in zero magnetic field. With application of magnetic field the temperatures for the dip and peak change in complicated ways. The peak disappears when a filed of 0.1 T is applied. βyx is negative and decreases with increasing temperature. At temperatures below 4 K βxx shows a positive peak at a field around 0.01 T in the field dependence. The previous theory for the anomaly of βxx around 4 K is extended to the case with magnetic field. The observed behavior for βxx in weak field region is ascribed to the trigonal band warping effect.
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  • Hideo Yoshioka, Yosuke Nagaoka
    1990 Volume 59 Issue 8 Pages 2884-2892
    Published: August 15, 1990
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    We calculate magnetic field dependence of the conductance of a ballistic quantum wire, a finite section of which is subjected to magnetic field. It is shown that the conductance is quantized and oscillates as changing magnetic field. The quantization results from the change in the number of subbands with changing magnetic field and the oscillation results from the Aharanov-Bohm interference due to edge states. We discuss the characteristics of these phenomena qualitatively.
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  • Yoshiyuki Ono, Akira Terai
    1990 Volume 59 Issue 8 Pages 2893-2904
    Published: August 15, 1990
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    Real time dynamics of a moving charged soliton in polyacetylene is studied numerically by using Su-Schrieffer-Heeger’s model. An electric field is introduced to the system through a time dependent vector potential which can be included into the Hamiltonian through the Peierls substitution of the phase factor to the transfer integral. Several interesting properties of the moving soliton are obtained, e.g., the Brownian-like motion of the soliton due to the soliton-phonon interaction, the saturation of the soliton velocity, the saturation velocity being independent of the applied electric field strength, while the time needed to attain the saturation velocity is, roughly speaking, linearly dependent on the logarithm of the applied field.
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  • Tôru Moriya, Yoshinori Takahashi, Kazuo Ueda
    1990 Volume 59 Issue 8 Pages 2905-2915
    Published: August 15, 1990
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    Spin fluctuations in antiferromagnetic and nearly antiferromagnetic two dimensional (square lattice) itinerant electron systems, as a possible model for high Tc superconductors, are investigated by using the self-consistent renormalization theory. The electrical resistivity and the nuclear spin relaxation rate due to the spin fluctuations in the normal state are calculated. The results in the nearly antiferromagnetic regime as applied to high Tc oxides seem to explain the experimental results both in their temperature dependence and in their orders of magnitudes. By using the same spin fluctuations we discuss superconductivity due to the spin fluctuation mechanism within a weak coupling theory. The order parameter is shown to have B1g or A2g symmetry and the critical temperature is evaluated to be of the right order of magnitude.
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  • Hiromi Otsuka
    1990 Volume 59 Issue 8 Pages 2916-2921
    Published: August 15, 1990
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    Using the quantum Monte Carlo simulation technique for the lattice fermion systems, we study the charge susceptibility of the two-dimensional Hubbard near the half-filled band. Lattice sizes up to 6×6 and inverse temperatures up to 6t(t: hopping parameter) are studied. We find that the behavior of the charge susceptibility is strongly dependent on the electron concentration at low temperature: the charge susceptibility is suppressed at the half-filled band, while it is considerably enhanced in non-half-filled band cases by the electron correlation. The above behavior of the charge susceptibility is quite similar to the recent Bethe-Ansatz result for the one-dimensional Hubbard model.
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  • Ichiro Hiromitsu, Jun Takeuchi, Takashi Ito
    1990 Volume 59 Issue 8 Pages 2922-2930
    Published: August 15, 1990
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    Magnetic properties of fluoro-aluminum phthalocyanine (AlPcF) film doped with tetracyanoethylene (TCNE) are studied by ESR. A strong pressure dependence is observed: At 760 Torr an antiferromagnetic transition takes place at 175±3 K, while, in vacuum, no magnetic transition is observed. DC conductivity does not have any pressure dependence. An X-ray diffraction study indicates that a pressure dependence of interlayer distance inside the film is a structural origin of the pressure dependence of the magnetism. A resonance mechanism of a charge transfer between AlPcF cation radical (Remark: Graphics omitted.) and TCNE anion radical (Remark: Graphics omitted.) is proposed in order to explain an interchain magnetic coupling.
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  • Yoshinori Takahashi, Hirokazu Tsunetsugu
    1990 Volume 59 Issue 8 Pages 2931-2940
    Published: August 15, 1990
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    Single hole propagation doped into a quantum antiferromagnet is studied taking into account the effect of finite exchange interaction up to the first order among antiferromagnetic spin background. Both even and odd moments of the hole density of states are evaluated. The results of the lower order moments suggest the existence of the string effect, which favors the hole localization in the small concentration region.
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  • Tosizumi Aoki
    1990 Volume 59 Issue 8 Pages 2941-2946
    Published: August 15, 1990
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    The thermodynamic properties of the square lattice Heisenberg antiferromagnet are investigated on the basis of the study of spin-wave excitation in previous paper [T. Aoki: J. Phys. Soc. Jpn. 59 (1990) 706]. The susceptibility and specific heat are calculated and compared with the results from other studies. The calculation of correlation function in the previous paper is reexamied and partly corrected. From this the existence of long-range order is shown and its amplitude is estimated. The agreement with numerical study is good. Our formula for inverse correlation length is compared with the recent neutron-scattering data of La2CuO4. If we choose J=1100 K, good agreement is obtained at low temperatures.
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  • Naoshi Suzuki
    1990 Volume 59 Issue 8 Pages 2947-2955
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    Magnetic excitations in the field-induced ferromagnetic states of hexagonal singlet-ground-state magnet RbFeCl3 are studied on the basis of the dynamical correlated-effective-field theory. It is shown that transition to a fan state (Hc) or to a cone state (H⁄⁄c) with decreasing field and/or temperature is driven by softening of a magnon mode at the K point in the Brillouin zone. The obtained softening behavior of the K magnon mode can explain qualitatively the temperature and field dependences of the NMR relaxation time T1 of Rb observed by Goto et al. It is also shown that the magnon mode originating from the single-ion excitation between the single-ion excited states for Hc can be observable by inelastic neutron scattering measurements for moderately high temperatures and strong fields.
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  • Hirofumi Wada, Masayo Hada, Keiichi N. Ishihara, Masayuki Shiga, Yoji ...
    1990 Volume 59 Issue 8 Pages 2956-2962
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    The low temperature specific heat of nearly and weakly ferromagnetic Y(Co1−xAlx)2 with 0≤x≤0.18 is studied between 1.4 K and 6.5 K. The results show an enhancement of the electronic specific heat coefficient, γ, around the critical concentration for ferromagnetism. A strong upturn in the CT vs T2 curve at low temperatures is observed for x≥0.09. The origin of this upturn is discussed in terms of different models so far proposed.
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  • Kenji Sumiyama, Yasuhiro Hirose, Yoji Nakamura
    1990 Volume 59 Issue 8 Pages 2963-2970
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    X-ray diffraction and magnetization have been measured for Fe1−xAlx alloys produced by facing target type DC sputtering. The bcc phase is obtained for x=0–0.65, the amorphous phase for x=0.7–0.9 and the fcc phase for x=0.9–1.0 on water-cooled (WC) substrates, while the bcc phase is obtained for x=0–0.55, the amorphous phase for x=0.65–0.95 and the fcc phase for x=0.95–1.0 on liquid-nitrogen-cooled (LNC) substrates. With increasing x, the average magnetic moment decreases and become zero at about x=0.5 for the alloys on WC substrates and at about x=0.65 for the alloys on LNC substrates. At low temperatures, spin glass characteristics are observed for x=0.3–0.7 in the alloys on WC substrates and for x=0.45–0.7 in the alloys on LNC substrates. These results indicate that the chemically random phases are more stabilized at the lower substrate temperature.
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  • Hiroyuki Shiba, Masao Ogata
    1990 Volume 59 Issue 8 Pages 2971-2975
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    The stability of the chiral spin state, which was proposed for the two-dimensional frustrated antiferromagnet on the square lattice, is critically examined by taking the local constraint into account. It is shown that the chiral spin state is relatively high in energy, suggesting it to be unstable. The instability of the flux state against the antiferromagnetic order is also demonstrated in this connection.
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  • Yoshihiro Yamada, Hiroyuki Nakamura, Yoshio Kitaoka, Kunisuke Asayama, ...
    1990 Volume 59 Issue 8 Pages 2976-2985
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    The 93Nb NMR and magnetization have been measured to investigate the nature of weak antiferromagnetism in the hexagonal C-14 Laves phase compound, NbFe2. The temperature and magnetic field dependence of the magnetization and nuclear spin-lattice relaxation time, T1, confirmed that an antiferromagnetic transition occurs at low fields and is easily suppressed by fields above 6 kOe. An analysis of T1 shows that both the ferro- and antiferromagnetic spin fluctuations coexist in this system and that the ferromagnetic component is dominant at high fields. The coexistence of two components of the spin fluctuation may be related to the anomalous temperature dependence of the magnetic susceptibility at high temperatures. The analysis of NMR spectra suggests that the magnetic structure at the ordered state is of the spin density wave type giving rise to a large distribution of hyperfine field.
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  • Kazuo Nakanishi
    1990 Volume 59 Issue 8 Pages 2986-2994
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    Nonlinear terms with respect to the magnetization are added to the free energy of the axial next-nearest neighbor Ising (ANNNI) model. Mean field calculations are made to investigate the phase diagram for both zero and nonzero magnetic fields. It is found that the nonlinear terms give a temperature dependent modification to the coupling constants of the conventional ANNNI model; this effect brings about a new phase transition. The nonlinear effect on the transition line between the ferromagnetic and modulated states under magnetic fields is also studied. A comparison is made between the theory and the phase diagram of CeBi in this context.
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  • Yoshihiro Ishibashi, Shinji Tanaka, Vladimir Dvo\v{r}ák
    1990 Volume 59 Issue 8 Pages 2995-2997
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    The low-temperature transition in K2Ba(NO2)4 is analyzed using a Landau-type thermodynamic potential function, and it is found that the low-temperature phase must be monoclinic if the transition is induced by the instability of a mode at k0=(1⁄2, 1⁄2, 1⁄2) of the Pbam phase.
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  • Takehisa Yoshinari, Toru Ebihara, Izumi Kotani, Yasushi Sato, Akira Su ...
    1990 Volume 59 Issue 8 Pages 2998-3002
    Published: August 15, 1990
    Released on J-STAGE: May 29, 2007
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    A new optical absorption band was found at the peak energy of 17 kcm−1 (590 nm) besides the Cl2 band (22.5 kcm−1=445 nm) in (CnH2n+1NH3)2MnCl4 (n=1, 2, 3) irradiated with X-rays at 15 K. The absorption intensity of the new band increases with the X-ray dosage in proportion to that of the Cl2 band. The intensity thermally decreases in two steps at temperatures around 50 K and 80 K accompanying the decrease of Cl2 band. The absorption band can not be bleached by the 590 nm light (17 kcm−1) at 15 K. The band is assigned to an electron center where an electron is trapped at the ammonium head in the neighborhood of a Cl vacancy.
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  • M. Staikova, M. Georgiev
    1990 Volume 59 Issue 8 Pages 3003-3011
    Published: August 15, 1990
    Released on J-STAGE: June 01, 2007
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    Electron transfer rates from excited F centers (F*) to nearby ground-state F centers (F0) via bound polarons are calculated using a semicontinuum model electronic potential in a two-mode coupling. The rate depends on the F*F0 separation through the corresponding dependence of the off-diagonal electron-phonon matrix element. Averaging over the F*F0 pair separations for a random F center distribution, concentration dependences are derived of intrinsic F center photoluminescent efficiencies in all f.c.c. alkali halides. In particular, the KCl result appears to agree fairly well with experimental concentration-quenching data.
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