Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 63, Issue 5
Displaying 1-50 of 52 articles from this issue
  • Atsushi Mori, Huzio Nakano, Kazumi Nishioka
    Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
    1994 Volume 63 Issue 5 Pages 1635-1638
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The diffuseness of the interface is investigated for the crystal-melt system by applying the previous thermostatistical theory of one of the present authors [H. Nakano: J. Phys. Soc. Jpn. 56 (1987) 641.] which gives the molecular theoretical expression for relevant parameters. By paying particular attention to such an expression for the inhomogeneity term in the free energy of the system as a function of the order parameter which indicates the crystallinity, the diffuseness is shown to decrease with the degree of inhomogeneity.
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  • Michiyasu Mori, Hidetoshi Fukuyama, Masatoshi Imada
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 5 Pages 1639-1642
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The spectrum of charge excitations, Im, N(q, , ω), has been evaluated near the Mott transition in the one-dimensional Hubbard model with a particular value of the Coulomb interaction. The present theory based on a continuum limit describes the smooth change between the Tomonaga-Luttinger liquid state with a q-linear mode and the Mott insulator with a charge gap, by considering Umklapp scattering. The charge susceptibility is seen to diverge proportional to the inverse of the doping rate as the Mott insulator state is approached, in agreement with Bethe-ansatz result. It is shown that the q region where the renormalization group theory and conformal field theory are valid becomes vanishingly small as the transition is approached.
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  • Yasuhiro Iye, Mark Baxendale, Vladimir Z. Mordkovich
    Subject area: Electronic transport in condensed matter.
    1994 Volume 63 Issue 5 Pages 1643-1646
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We have observed a new angular oscillatory magnetotransport phenomenon in the out-of-plane resistivity of stage 2 SbCl5-intercalated graphite. The phenomenon is similar in many respects to the one recently found in organic conductors, which is attributed to a semiclassical geometrical resonance effect inherent in a weakly corrugated cylindrical Fermi surface. Some deviations from the “standard” behavior are found.
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  • Yoshimasa Isawa, Masahiro Seko
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1647-1651
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We present a theoretical study of two small normal tunnel junctions connected in series and driven by a dc voltage source, using Keldysh's approach for the nonequilibrium state and taking the current continuity into account by adjusting the electrochemical potential μ in the island. The numerical results of the Coulomb Blockade of tunneling conductance show that the lowest order of the tunneling processes can explain the experimental results qualitatively when the tunneling resistance RT is large compared with the resistance quantum RQ=h/2e2.
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  • Masaaki Kontani, Hiroshi Ido, Hideko Ando, Takashi Nishioka, Yuuji Yam ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1652-1655
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We report magnetic susceptibility, electrical resistivity and specific heat measurements of single-crystal as well as poly-crystalline specimens of CeCuAl3 with the tetragonal BaAl4-type superlattice. The low-temperature specific heat C of either sample exhibits a peak at 2.3-- 2.8, K due to the antiferromagnetic transition, but even above the Néel temperature, C/T attains a large value of about 0.8, J/K2 mol-Ce, suggesting that CeCuAl3 is a heavy-fermion antiferromagnet. The observed anisotropic susceptibility is well fitted to the calculated one based on a single-ion crystalline field model.
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  • Masayuki Shiga, Hiroyuki Nakamura, Masakazu Nishi, Kazuhisa Kakurai
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1656-1660
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Polarized neutron scattering measurements have been performed on β-Mn and β-Mn0.9Al0.1 to study spin fluctuations. A large magnetic scattering peak at around Q=1.5, Å-1 was observed in the spectra obtained in the quasi-elastic condition, indicating the existence of strong spin fluctuations with antiferromagnetic correlation. The energy and Q spectra at 290, K exhibit nearly the same profiles and intensity for both samples. However, the energy spectra at low temperatures are quite different. For the pure β-Mn, the intensity decreases with decreasing temperature and the energy width remains as broad as at 290, K. For β-Mn0.9Al0.1, on the other hand, the intensity increases due to narrowing of the energy spectrum at low temperatures, implying a slowing down of spin fluctuations. These results are discussed in terms of a spin-liquid to spin-glass transition caused by Al substitution.
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  • Masatoshi Arai, Masaki Fujita, Katsunori Ubukata, Takahiro Bokui, Kiyo ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1661-1665
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Crystal structure and phonon dynamics up to 150, meV of the spin-Peierls material CuGeO3 have been investigated by neutron scattering experiments. We found a large lattice anomaly in the a-b plane, vertical to the one-dimensional antiferromagnetic spin chain, associated with additional diffraction peaks in the b*-axis at temperatures much higher than the spin-Peierls transition temperature. The phonon modes of the chain oxygens at 100, meV show consistent evolution with diffraction. Therefore, we conclude that the structural evolution of the chain oxygens in the a-b plane, which mediates the spin-spin interaction along the c-axis, drives the spin-Peierls transition.
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  • Masaaki Yamaguchi, Masayasu Ishikawa
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1666-1669
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Magnetic phase transitions in Cr2WO6, Cr2TeO6 and Fe2TeO6 were investigated from the measurements of magnetic susceptibility and specific heat. The magnetic susceptibility exhibited only broad maxima as a function of temperature around 80, K, 105, K and 240, K for Cr2WO6, Cr2TeO6 and Fe2TeO6, respectively, whereas the specific heat showed sharp peaks implying 3-dimensional long-range order at 45, K, 93, K and 206.5, K for the above compounds, respectively. The confusing aspect of these magnetic phase transitions is, however, reconciled with Fisher's notion by means of the temperature derivative of the susceptibility for simple antiferromagnets. Such results give evidence for important short-range low-dimensional magnetic correlations above the 3-dimensional ordering in these materials.
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  • Susumu Sasaki, Azusa Matsuda, C. W. Chu
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 5 Pages 1670-1673
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    This Letter reports on NMR studies of 13C in K3C60 above and below Tc with an applied field of 2.93, T. It is found that non-single-exponential recovery data can be fitted by two components and normalized to an identical shape. With T1 defined in this way, Fermi-liquid behavior is identified above Tc, and a broadened Hebel-Slichter peak observed below Tc is well explained by the Eliashberg theory with 2Δ(0)/kBTc=4.31. The possibility of strong electron correlation and the origin of the multi-exponential recovery are discussed.
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  • Yumi Shimoo, Fumiaki Shibata
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 5 Pages 1674-1676
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    A stochastic path integral theory of low field resonance and relaxation is developed. This theory is applicable to systems with several spins under time-dependent random perturbations. Moreover, the theory can be used for powder samples as well as single crystals. As an illustrative example, time evolution is calculated explicitly for a powder system composed of two spins.
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  • Kichizo Asai, Yoshitaka Ohkubo, Takuya Okada, Yasuo Yanagida, Yoichi K ...
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 Volume 63 Issue 5 Pages 1677-1680
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Hyperfine magnetic fields, Hhf, at 117In arising from 117Cd were measured in Fe3O4 by time-differential perturbed angular correlation (TDPAC) of 90--345, keV γ-rays through the intermediate 660, keV state (3/2+). The values of Hhf were found to be 123 and 138, kOe at 295 and 77, K, respectively. The present work is the frrst one which measured Hhf at 117In in magnetically ordered materials, and demonstrates the applicability of TDPAC of this nuclide in the field of magnetism.
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  • Hironobu Kasano, Hirotake Shigematsu, Hiroyuki Mashiyama, Yutaka Iwata ...
    Subject area: Dielectric properties and materials.
    1994 Volume 63 Issue 5 Pages 1681-1684
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Low-temperature phase transitions in Rb2ZnBr4 single crystal were reinvestigated by means of neutron and X-ray diffractions. Below 116, K some superlattice reflections appeared at the same position (h/2, , k/2, , 0) as in other members of Rb2ZnCl4 group crystals, where h and k denote the Miller indices in the normal phase (space group Pmcn). The temperature dependence of the integrated intensity of the superlattice reflection changed below 78, K. However, the anomaly around 50, K reported previously was not observed. Below 116, K an incommensurate phase as reported for K2ZnCl4 was not detected. The space group of phase between 78 and 116, K was directly confirmed to be C1c1 by the verification of extinction rules of X-ray diffraction.
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  • Mitsuyoshi Tomiya
    Subject area: Classical and quantum physics: mechanics and fields.
    1994 Volume 63 Issue 5 Pages 1685-1690
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We study Lie algebraic structure of the generalized parasupersymmetric quantum mechanics (GPQM). The GPQM was suggested by V. A. Rubakov and V. P. Spiridonov, 1) and proposed by us.2) The parasuperalgebra of the GPQM can be interpreted into the “supersymmetrization” of su(l+1) by the use of the pseudo-differential operator D-1. We also mentioned that the GPQM's can be also constructed by the “supersymmetrization” of the other Lie algebras, e.g. o(2l), o(2l+1), sp(2l).
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  • Naomichi Hatano
    Subject area: Statistical physics and thermodynamics.
    1994 Volume 63 Issue 5 Pages 1691-1697
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Methods of analyzing data of quantum Monte Carlo simulations with the negative-sign problem are studied. It is pointed out that naive data analyses yield an overestimated statistical error or a quite unstable result. Two proper ways of analyzing the data are presented.
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  • Yoshiki Hidaka, Kazurou Shimokawa, Tomoyuki Nagaya, Hiroshi Orihara, Y ...
    Subject area: Statistical physics and thermodynamics.
    1994 Volume 63 Issue 5 Pages 1698-1712
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    In the electro-hydrodynamic systems of nematic liquid crystals with free and rigid boundaries and a small aspect ratio, the pattern evolution process on applying the stepwise ac voltage was studied. The convective rolls appeared at the both lateral sides of the system, and evolved toward the center. It was found that the pattern is selected through the phase jump. The pattern in the free lateral boundary cell had more flexibility than in the rigid lateral boundary cell. The interactions between the two subsystems separated by free lateral boundary and the selection of the pattern were studied. It was found that the evolution and the selection of the pattern in a subsystem were affected by those in the other subsystem through the free boundary.
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  • Yasuo Udagawa, Hisashi Hayashi, Kazuyuki Tohji, Takanori Mizushima
    Subject area: Atomic spectra and interactions of atoms with photons.
    1994 Volume 63 Issue 5 Pages 1713-1720
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Resonant effect in X-ray Raman spectra of various copper(I) and copper(II) compounds was studied by using tunable X-rays from synchrotron radiation. Prominent excitation energy dependence in spectral shape as well as in intensity was observed and analyzed in terms of simple equations derived from Kramers-Heisenberg equation. Anomaly in spectral shape was observed for Cu(II) compounds and it is ascribed to existence/nonexistence of a vacant 3d orbital in Cu(II)/Cu(I) compounds.
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  • Abou El Magd A. Mohamed, Elsayed F. A. Elshehawey, Yusry O. El–d ...
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 5 Pages 1721-1737
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The weakly nonlinear electrohydrodynamic stability of fluid layer sandwiched between two semi-infinite fluids is investigated. The nonlinear theory of perturbation is applied for symmetric and anti-symmetric modes. The method of multiple scales is used to expand the various perturbation quantities to yield the linear and successive nonlinear partial differential equations of the various orders. The solutions of these equations are obtained. The application of the boundary conditions leads to two nonlinear Schrödinger equations. It is found that the presence of the tangential field plays a stabilizing role and can be used to suppress the instability of the system at a given wavenumber which is unstable linear stability. Numerical calculations show a global stability for certain wavenumbers. A local instability is also observed in the graphs. The field plays a dual role. It is observed that the change of the layer thickness redistributes the stable areas.
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  • Takashi Atobe, Mitsuaki Funakoshi
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 5 Pages 1738-1753
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Chaotic or regular motions of the fluid particles by the Stokes flow between two eccentric cylinders counter rotating alternately and of radius ratio 0.3 are investigated numerically and analytically. We examine the dependence of the motions on eccentricity ε, focusing on an equilibrium point of the Poincaré map of the particle position after every rotations. If both of the winding numbers of the cylinders are small, the area of the chaotic region is small and increases monotonically with ε, whereas when at least one of them is not small, this area is relatively large and takes a maximum at a certain ε. In the latter case, within a certain region of the winding numbers, the bifurcation of the equilibrium point from elliptic to hyperbolic type occurs at another value of ε=εb, resulting in the increase in the area for ε around εb. A perturbation analysis can roughly predict this region and the value of εb.
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  • Kimiaki Konno, Yoshi H. Ichikawa
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 5 Pages 1754-1757
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Two experiments of vortex filament done by Hopfinger et al. and Maxworthy et al. are analyzed with the integrable vortex equation with axial flow. It is found that, on the contrary to the case of Hasimoto soliton, the effect of the axial flow explains the group velocity and the phase velocity of vortex soliton for both experiments without contradiction. Momentum and angular momentum transport by vortex soliton is calculated.
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  • Naoko Tokugawa, Ryuji Takaki
    Subject area: Fluid dynamics.
    1994 Volume 63 Issue 5 Pages 1758-1768
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Mechanism of self-induced vibration of a superheated liquid drop, which is levitated on a hot-plate with a thin vapor sheet in between, is analyzed experimentally and theoretically. Temperature distribution of a liquid drop at the surface and inside has been measured, and found not to be constant, which suggests dominance of the surface tension fluctuation. A model is proposed, where the liquid drop is assumed to be a thin liquid layer, and the potential flow is assumed inside the layer. The flow in the thin vapor sheet is assumed to be a superposition of Hele-Shaw flow and Couette flow. Magnitude of the surface tension is assumed to vary, due to the contact of the peripheral region of the drop with heated air surrounding it. Analysis based on this model gives stable stationary vibration with finite amplitude. The obtained vibrational amplitude agrees with experimental data.
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  • Tae Hun Chung
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 5 Pages 1769-1774
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    A quantum mechanical description of the interaction of a gyrating free-electron in uniform magnetic field with a single-mode fully quantized electromagnetic field is presented. The interaction Hamiltonian including RWA terms are obtained for the linearly polarized and circularly polarized electromagnetic waves. And the normal mode frequency of the vibrations and eigenstates are calculated. Emission and absorption characteristics associated with cyclotron motion of an electron are also discussed.
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  • Reiji Sugaya
    Subject area: The physics of plasmas and electric discharges.
    1994 Volume 63 Issue 5 Pages 1775-1793
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The velocity space diffusion equation which describes a distortion of the velocity distribution function due to nonlinear wave-particle scattering (nonlinear Landau damping) of electromagnetic and electrostatic waves in a homogeneous magnetized plasma is derived from the Vlasov-Maxwell equations by perturbation theory. The velocity space diffusion equation is expressed by means of the tensors of four-order which are transformed into some simple and convenient forms. The transport equations describing energy and momentum transfer between waves and particles are expressed by nonlinear wave-particle coupling coefficients, and yield the conservation laws for total energy and momentum densities of waves and particles. These equations are greatly useful for analysis of particle acceleration and plasma heating induced by the nonlinear wave-particle scattering.
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  • Shin"ichi Takeda, Masanori Inui, Shigeru Tamaki, Kenji Maruyama, ...
    Subject area: Structure of liquids and solids; crystallography.
    1994 Volume 63 Issue 5 Pages 1794-1802
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The structure factor of liquid Mg has been obtained at 680°C by neutron diffraction with sufficient accuracy for the first time. The X-ray and neutron diffraction results indicate a clear difference, from which the electron density distribution and electron-ion correlation functions in liquid Mg have been evaluated.
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  • Yukio Noda, Itaru Tamura, Hironori Nakao, Ryuji Matsuo, Yoshihiro Kuro ...
    Subject area: Structure of liquids and solids; crystallography.
    1994 Volume 63 Issue 5 Pages 1803-1807
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Low temperature Weissenberg photograph of K3D(SO4)2(-- 92\associated with the phase transition. Three type superlattice reflectionswere found below Tc (77.5, K), ones at(0 {1em}± 1/2 {1em}± 1/2) V-point and others atlattice points (Z and Γ-points) violating the extinctionrule of the space group A2/a of the high temperature phase. Thediffuse scattering was observed above Tc around(0 {1em}1/2 {1em}1/2) type reflection. It was revealedthat the double q condensation occurred at the V-point and ones atthe Z and Γ-points were secondary order parameters. Theunit cell of the low temperature phase was determined asa× 2b× 2c, and the space group was A2.
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  • Nobuaki Toyoshima, Kazuo Harada, Hiroshi Abe, Ken–ichi Ohshima, ...
    Subject area: Structure of liquids and solids; crystallography.
    1994 Volume 63 Issue 5 Pages 1808-1813
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    With the use of the X-ray diffraction technique, we have observed temperature-independent extra diffuse scattering (EDS) close to Bragg reflections in the face centered cubic (fcc) phase of an In-23, at. scattering (TDS). The EDS is understood to originate from the intrinsic deformations in the specimen. No diffuse scattering due to precursor phenomena was detected in the diffraction pattern. An incubation time of more than several hours for which the crystal temperature was maintained at 256±0.02, K, its martensite start temperature Ms, was required to transform from the fcc structure to face centered tetragonal (fct) structure. The fcc structure was completely recovered from the fct structure on warming the crystal from a temperature below Ms back to room temperature.
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  • Yoshiyuki Shirakawa, Shigeru Tamaki, Takeshi Usuki, Kazumasa Sugiyama, ...
    Subject area: Structure of liquids and solids; crystallography.
    1994 Volume 63 Issue 5 Pages 1814-1820
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Neutron diffraction experiments have been carried out for molten CuCl--CuBr and AgBr--AgI systems along their liquidus curves. For molten CuCl--CuBr mixtures, the contraction of the interionic distance has been found. The concentration dependence of the result is consistent with that found in the magnetic susceptibilities for this system. Molten AgBr--AgI mixture shows an expansion of the interionic distance in their concentration dependence.
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  • Fuyuki Shimojo, Kozo Hoshino, Mitsuo Watabe
    Subject area: Structure of liquids and solids; crystallography.
    1994 Volume 63 Issue 5 Pages 1821-1827
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    An analysis of the second-order memory functions, N(k, , t) and Ns(k, , t), by the mode-coupling theory is presented for the density correlation function F(k, , t) and its self-part Fs(k, , t), respectively, of liquid sodium near the triple point. The results obtained by the theory are compared with those of our recent molecular dynamics simulation. It is shown that the mode-coupling theory can explain quantitatively the behavior of the self-part Ns(k, , t) in the wide range of wavenumber k, though there appear small discrepancies between the theoretical and the MD results only within a small interval 0.1-- 0.2, ps with increasing k. On the other hand, as for N(k, , t), though the results obtained theoretically for small k are in good agreement with those obtained by the MD simulation, we have observed significant discrepancies between the theoretical and the MD results for relatively large k. That is, the theoretical curves have unexpected humps which are not observed in the MD simulation.
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  • Seishi Yamamoto, Tomoko Hosokawa
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1994 Volume 63 Issue 5 Pages 1828-1834
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    X-ray diffuse scatterings are observed in cubic adamantane (C10H16) around X-points and Z-lines in the Brillouin zone boundary. The intensity of the diffuse maximum at the X-point increases with decreasing temperature. Diffuse intensity distribution is analyzed with the molecular field approximation in the Ising system. Cubic-tetragonal phase transition is explained by the instability of the orientational fluctuation with a wave vector q=(0, , 0, , 2π/a): X-point. Short-range interaction between the first neighbouring molecules plays a dominant role in this phase transition.
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  • Chikara Sugiura
    Subject area: Electron states in condensed matter.
    1994 Volume 63 Issue 5 Pages 1835-1847
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    With a two-crystal vacuum spectrometer equipped with beryl crystals, the Cu Lα emission spectra in fluorescence have been measured for selected copper compounds Cu2O, CuO, CuCl, CuBr, CuI, CuF2, CuCl2, CuBr2, CuF2·2H2O, CuCl2·2H2O and Cu3P, and alloys α-Cu+35 grouped into three classes. The first class comprises the spectra of alloys, which consist of a single broad band similar to that of Cu metal. The second class includes the spectra of monovalent copper compounds, which are composed of a prominent peak and its high- and low-energy structures. To the third class belong the spectra of divalent copper compounds, which consist of a strong peak accompanied with a characteristic dip and hump on the high-energy side. The Cu Lα emission bands of Cu2O, CuCl and CuBr are compared with available XPS spectra and theoretical Cu-3d-DOS.
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  • Richard Lang, Masuo Fukui
    Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
    1994 Volume 63 Issue 5 Pages 1848-1860
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    This paper is dedicated to the theoretical study of aluminum and silver bilayer systems submitted to an optical electromagnetic field. The bulk metallic layers are considered as neutral “jelliums” while the surface regions are modelled in terms of macroscopic as well as microscopic physics and they are referred to as “selvedges”. These contain within their boundaries all interface roughness and surface atomic inhomogeneities. Furthermore, since the charge neutrality of the bulk media is broken close to the surface, the selvedges will also contain static charge densities that have appeared in order to screen them. When the selvedges are submitted to an incident optical beam, they are considered to be polarised and therefore emit supplementary fields. These are calculated with the help of the Heaviside notation and as a function of the electric polarisation and the electronic charge density distribution. An hydrodynamic approach and therefore Euler's equation were adopted in this case to account for the electronic dynamics in the selvedge.
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  • Hiroshi Shimahara
    Subject area: Superconductivity.
    1994 Volume 63 Issue 5 Pages 1861-1870
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Magnon exchange mechanism of superconductivity is studied on the basis of the spin fermion model or a generalized Kondo lattice model, where the antiferromagnetic long range or short range order exists in the localized spins. We obtain the effective interaction and the gap equation taking into account the two magnon exchange interaction. The gap equation is solved just below the transition temperature in the quasi-two-dimensional cases. As a result, it is found that the triplet pairing superconductivity is favored for dilute fermion densities, while the singlet pairing is favored for high densities. The transition temperature is found to be very low for realistic parameters. The possibility that the superconductivity by the magnon exchange interaction is observed experimentally is discussed.
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  • Toru Moriya, Kazuo Ueda
    Subject area: Superconductivity.
    1994 Volume 63 Issue 5 Pages 1871-1880
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The spin fluctuation mechanism for the high temperature superconductivity in cuprates is investigated with a parametrization of the spin fluctuation spectra in terms of the self-consistent renormalization theory of spin fluctuations. The doping concentration dependence of the transition temperature in the best studied cuprates is explained in terms of the parameter values estimated from the normal state experiments. We find that the larger the amplitude and the energy spread of spin fluctuations, the higher Tc. In this context the cuprates have much favorable properties compared with some other antiferromagnetic spin fluctuation systems whose parameter values are estimated for comparison.
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  • Shinpei Fujii, Shoji Ishida, Setsuro Asano
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1881-1888
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We have performed energy-band calculations of X2Mn1-xVxSi (X=Fe and Co) at x=0, 0.25, 0.5, 0.75, 1.0. In ferromagnetic ordering, we obtain excellent agreement between calculated and experimental data for the magnetic moment per formula unit and the lattice constant, at each Mn content. We have obtained the result that state densities in Fe2Mn1-xVxSi have a large peak at the Fermi level, while they do not in Co2Mn1-xVxSi. We have also estimated Heisenberg exchange constants from total energy differences between ferromagnetic and antiferromagnetic orderings. The Curie temperature roughly calculated from the exchange constants increases from x=0 to x=0.5 and then decreases rapidly in Fe2Mn1-xVxSi, though it monotonically decreases from x=0 to x=0.75 in Co2Mn1-xVxSi. The behavior of calculated Curie temperatures in Fe2Mn1-xVxSi is consistent with the observed one.
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  • Makoto ISODA, Yoshinori Takahashi, Toru Sakai
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1889-1899
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    A microscopic model is proposed to describe magnetic properties of half-metallic f-electron systems. We explicitly take into account the energy gap in the conduction band and the intra-atomic exchange interaction between localized f-electrons and conduction eleictrons. Based on the model Hamiltonian, the temperature dependence of the magnetic properties are studied assuming the ferromagnetic ground state. The relative stability of ferromagnetic state against antiferromagnetic state is also discussed by perturbation expansion in terms of the hybridization between the conduction and the localized f-electron states. Some implications are given for UNiSn, which shows the transition from paramagnetic semiconductor to antiferromagnetic metal by lowering temperature.
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  • Kazuaki Iwasa, Masakazu Nishi, Hironobu Ikeda, Jun–ichi Suzuki
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1900-1907
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The magnetic structure along the axial direction in the layered antiferromagnets, Rb2MnF4 and Cs2MnF4, was studied under hydrostatic pressure by using neutron scattering techniques. These compounds revealed predominantly antiferromagnetic stacking of magnetic layers at ambient pressure below their Néel temperatures. Upon applying pressure, however, the stacking changed remarkably; the ferromagnetic stacking became dominant and antiferromagnetic stacking completely vanished. Besides these two dominant peaks, several small peaks, which correspond to longer-period stacking, were also observed. These results are qualitatively explained by taking the competing interplanar interactions into consideration.
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  • Takashi Kawashima, Akihide Oguchi
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1908-1915
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    We study magnetic behavior of a completely random dilute S=1/2 anisotropic Heisenberg antiferromagnet on the two-dimensional square lattice by using the coherent potential approximation. In the anisotropic Heisenberg model, the xy-anisotropy defined by Jp(z)/Jp(xy) is enhanced with increasing nonmagnetic impurities, where Jp(z) and Jp(xy) are the z and xy components of the coherent exchange constant, respectively. On the other hand, the isotropic Heisenberg model retains the isotropic nature for any impurity concentration. The critical concentration at the percolation threshold is obtained. The Néel temperature and the magnitude of the coherent exchange constant are calculated as a function of the impurity concentration.
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  • Seizo Watarai, Seiji Miyashita
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1916-1927
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Nature of ordered phases of Ising-like Heisenberg antiferromagnets on the hexagonal (layered triangular) lattice is investigated by making use of a Monte Carlo method and mean field analysis. Two phase transitions are found, which correspond to the orderings of the z-component and of the xy-components of the spins, respectively. The uniform magnetization along the easy axis is found in ordered phases with a concave curve as a function of the temperature and the spin configuration of the ordered phases is found to be a three-sublattice ferrimagnetic one. In the low temperature phase, the effect of the nontrivial degeneracy (NTD) of the ground state which is inherent to the present model is investigated. NTD causes a nontrivial enhancement of the fluctuation of the uniform magnetization in the hard plane. The magnetization processes in the ground state for fields along the x-axis are also studied.
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  • Shozo Takeno, Kazuko Kawasaki
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1928-1839
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    A theory of elementary excitations in Heisenberg ferromagnets with anisotropic exchange interactions is formulated without assuming the smallness of spin deviations from the ground state. This is done by using a path integral formalism in the SU(2) coherent state representation combined with the use of the stationary-phase approximation. Equations for spin-deviation field variables are solved in an approximate analytical form to show the existence by the intrinsic nonlinearity of mobile and immobile self-localized magnons in one- and d-dimensional cases, respectively. Discussions are given on their characteristic properties such as the energy eigenvalues lying below the linear spin-wave energy band, dispersion curves and localized-mode profiles. These intrinsic nonlinear modes can be considered as a natural extension of conventional (linear) spin waves to the nonlinear, soliton regime.
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  • Kaichi Saito, Susumu Matsuo, Hiroshi Nakano, Tsutomu Ishimasa, Masahir ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1940-1947
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The magnetization of a stable single-grained Al70Pd21Mn9 icosahedral quasicrystal has been investigated in the temperature region between 2 and 600, K below the magnetic field 80, kOe. The susceptibility yields a Curie constant 1.75×10-4, cgsemu·K/g, a Curie temperature -1.62, K, and a constant susceptibility contribution -0.25× 10-8 cgsemu/g. Magnetization curves at low temperatures suggest that only about 1 magnetic. The temperature dependence of the susceptibility above 300, K shows a positive T2 contribution, which has been first observed in magnetic quasicrystals and is considered to originate from a pseudogap in the electronic density of states at EF causing the stability. Temperature- and magnetic-field-dependencies of the electrical conductivity are well accounted for by a weak localization theory including spin and spin-orbit scattering. The agreement between the experimental data and the fitting is not improved by adding the diffusion channel contribution of electron-electron interaction effects.
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  • Seishi Takagi, Kenji Nakao, Kazumi Nakatsu
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1948-1960
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    The crystal structure and magnetic properties of an organic ion-radical salt, 1, 3'-diethyl-2, 2'-quinoselenacyanine-[TCNQ]2, are reported. The salt forms triclinic crystal in the space group P\overline{1} with a=14.180(3), b=17.689(2), c=8.244(1)Å, α =103.13(1), β =93.14(1), γ =70.06(1)° and Z=2. The spin-susceptibility of the salt shows two broad maxima near 45 and 195, K. A single ESR absorption line is observed for single crystals above 40, K and its linewidth strongly depends on the temperature and external magnetic field direction. On the contrary, two side lines due to an excited triplet state are observed below 40, K with a central line. These experimental results are discussed on the basis of the peculiar crystal structure of the salt.
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  • Tatsuo Kobayashi, Akihiro Kohda, Kiichi Amaya, Masakazu Ito, Hiroyuki ...
    Subject area: Magnetic properties and materials.
    1994 Volume 63 Issue 5 Pages 1961-1966
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Heat capacity and susceptibility measurements are performed down to 70, mK under magnetic fields in the Haldane-gap antiferromagnet (CH3)4NNi(NO2)3 (TMNIN). We have observed no magnetic long range order within our experimental range of the temperature down to 70, mK and the magnetic field up to 7, T. The heat capacity reflects the field dependence of the energy gap and show a broad anomaly above a critical field HC, which has been also observed in NENP. In the adiabatic magnetization measurement, the spin temperature shows a minimum around HC. These results are interpreted as increasing of the energy gap above HC which may suppress the expected long-range-ordering.
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  • Akinobu Ogiwara, Toshihiro Ohashi, Yoshihiro Ohmura
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1994 Volume 63 Issue 5 Pages 1967-1975
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Numerical values of the exponents of Li, Na, Mg and Al in the theory of Nozières and De Dominicis (Phys. Rev. 178 (1969) 1097) on the anomalous edge of soft X-ray spectra are calculated. The exchange effects are included explicitly as corrections to the previous values calculated by Ohmura and Sano (J. Phys. Soc. Jpn. 43 (1977) 875). By the corrections, all the positive values of α0 for L holes of Na, Mg and Al decreased, while the negative value of α1 for the K hole of Li increased approaching to zero. All these results could be compared more favorably with existing experimental results done recently than the one obtained previously. The results support, on reflection, the previous calculation of α0 on K and Rb (J. Phys. Soc. Jpn. 58 (1989) 4635) done in the same way as in the present paper.
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  • Tetsuhiko Tomiki, Yoshiiku Ganaha, Tohru Shikenbaru, Tomoyoshi Futemma ...
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1994 Volume 63 Issue 5 Pages 1976-1985
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Anisotropic reflectivity spectra of YAlO3 single crystals at 297, K measured with the light polarized parallel to each of the a, b and c axes are presented in the range from -- 6.5, eV to -- 120, eV. A comparison of the reflectivity spectra of YAlO3 with those of Y2O3, Y3Al5O12 and α-Al2O3 single crystals reaffirms that the peaks at -- 35, eV are mainly associated with the Y3+4p6 and the features beyond -- 76, eV with the Al3+L2, 3. Anisotropic reflectivity spectra at 10, K are shown in the region from -- 7, eV to 15, eV. Effective optical dielectric constants calculated by the sum rule including the imaginary part of the dielectric constant up to -- 120, eV are seen to saturate at the values corresponding to 98.0 literature values of the optical dielectric constant.
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  • Atsushi Ikawa
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1994 Volume 63 Issue 5 Pages 1986-1994
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    Optical absorption spectra of a regular Se chain are calculated with an INDO type model under the Hartree-Fock and single excitation configuration interaction approximations. The calculated spectra can explain the observed ones in isolated Se chains in mordenite channels (M-Se). If the chain is compressed along the chain axis, its dihedral angles become smaller and the lowest singlet excitation shifts toward lower energies. The red shift explain the observed ones in M-Se under pressure. It is suggested that the observed red shifts of the LP (lone pair) → σ* absorption peaks in liquid S and Se with the increase of temperature in semiconducting regions are due to the increase of bond angles in the chains.
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  • Q. J. A. Khan, B. S. Bhatt, R. P. Jaju
    Subject area: Other areas of research of general interest to physicists.
    1994 Volume 63 Issue 5 Pages 1995-2001
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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    A system of differential equations of dispersion between two populations in habitats separated by a barrier with a predator feeding intensively on the more abundant habitats population has been considered. A comprehensive study has been made when predator feeds prey indiscriminately and when it feeds preferentially on the most numerous prey species. Equilibrium and stability analysis have been carried out for both the models.
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  • K. H. Chung, P. M. Hui
    Subject area: Statistical physics and thermodynamics.
    1994 Volume 63 Issue 5 Pages 2002-2003
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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  • Masatoshi Kajita
    Subject area: Atomic and molecular collision processes and interactions.
    1994 Volume 63 Issue 5 Pages 2004-2005
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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  • Takanori Fukami, Kazuyasu Tobaru, Kazuhito Kaneda, Keiko Nakasone, Kaz ...
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1994 Volume 63 Issue 5 Pages 2006-2007
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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  • Riki Kawashima, Takahiro Sasaki, Hiroshi Isoda
    Subject area: Transport properties of condensed matter (nonelectronic).
    1994 Volume 63 Issue 5 Pages 2008-2009
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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  • Michisuke Kobayashi, Osamu Sato, Yukio Tanaka, Akira Hasegawa
    Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
    1994 Volume 63 Issue 5 Pages 2010-2011
    Published: May 01, 1994
    Released on J-STAGE: October 01, 1999
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