Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 71, Issue 1
Displaying 1-50 of 57 articles from this issue
  • Zhaosheng Feng
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 1-4
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    In this letter, we propose a new approach to studying the one- and two-dimensional Burgers-Korteweg-de Vries equation. The results indicate that the solutions obtained in the literature are either particular cases of our results, or contain errors.
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  • Fujio Shimizu, Jun-ichi Fujita
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 5-8
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The specular reflectivity of slow, metastable neon atoms from a silicon surface was found to increase markedly when the flat surface was replaced by a grating structure with parallel narrow ridges. For a surface with ridges that have a sufficiently narrow top, the reflectivity was found to increase more than two orders of magnitude at the incident angle θ of 10 mRad from the surface. The slope of the reflectivity vs θ near zero was found to be nearly an order of magnitude smaller than that of a flat surface. A grating with 6.5% efficiency for the first-order diffraction was fabricated by using the ridged surface structure.
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  • Philippe Blanchard, Max-Olivier Hongler
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 9-11
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The inverse Gaussian probability density is shown to describe the statistical properties of the height of a pile of blocks in the experiment of Iwasaka and Honda. Our derivation furnishes an elementary analytical result for models exhibiting a self-organized behavior. Moreover, the method we use, based on the first hitting time of a stochastic process to a moving boundary, suggests natural generalizations for more complex systems.
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  • Yukinobu Kawakita, Shinichi Takeda, Takeshi Enosaki, Kouji Ohshima, Hi ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 12-14
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Neutron diffraction measurements have been performed for liquid germanium over a wide temperature range from 1000°C to 1550°C. The structure factor of liquid germanium just above the melting point has a pronounced shoulder in the high momentum transfer region of the first peak, as also by our data confirmed. With increasing temperature, the position of the first peak moves slightly to a high value of Q and the shoulder becomes inconspicuous.
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  • Akinori Awazu
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 15-18
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The appearances and the change of the frictional force of a system with two hard spheres in a two-dimensional rectangular box are discussed. With controlling the pressure or the supply of energy from the wall, the solid-like state, the solid-liquid temporal coexistence state, and the liquid-like state are observed. The frictional force and the fluidity of the system are measured under the shear. By varying the shear, a marked change of frictional forces is observed with similar characteristics to those of the static and dynamic frictions of a solid-on-solid system. Moreover, the relationship between the above frictional force and the shear is found to show strong temperature dependency. The hysteresis loop in the friction-velocity relation on granular layers [S. Nasuno et al.: Phys. Rev. Lett. 79 (1997) 949] is discussed on the base of these results.
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  • Masaru Onoda, Naoto Nagaosa
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 19-22
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The anomalous Hall effect in two-dimensional (2D) ferromagnets is considered to be the physical realization of the parity anomaly in (2+1)D, and the band crossing points behave as the topological singularity in the Brillouin zone. These band crossing points appear as sharp peaks and sign changes of the transverse conductance σxy as a function of the Fermi energy and/or the magnetization. The relevance to the experiments including three-dimensional (3D) systems is also discussed.
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  • Noriyuki Nakai, Masanori Ichioka, Kazushige Machida
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 23-26
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The vortex structure is studied in light of MgB2 theoretically based on a two-band superconducting model by means of Bogoliubov-de Gennes framework. The field dependence of the electronic specific heat coefficient γ (H) is focused. The exponent α in γ (H)∝ Hα is shown to become smaller by adjusting the gap ratio of the two gaps on the major and minor bands. The observed extremely small value α ∼ 0.23 could be reasonable in this two-band model with the gap ratio ∼0.3.
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  • Akihiko Machida, Yutaka Moritomo, Shigeo Mori, Naoki Yamamoto, Kenji O ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 27-30
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Microscopic magnetic structures of Tb1-xCaxMnO3 (x ∼ 1) have been investigated by means of small-angle neutron scattering (SANS) and Lorentz micrograph experiments. We have found that ferromagnetic microclusters of the order of ∼10 nm are invaded in the antiferromagnetic matrix with the G-type spin structure. We have interpreted the coexistence of the magnetic clusters in terms of intrinsic change separation.
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  • Hiroyuki Takagiwa, Kazuki Ohishi, Jun Akimitsu, Wataru Higemoto, Ryosu ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 31-34
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The magnetic properties of Ce0.7La0.3B6 single crystal have been studied by muon spin relaxation (μSR). The absence of a clear muon spin precession under zero external field in phase IV indicates that no commensurate long-range magnetic order is present in this phase. Moreover, the time spectra under a longitudinal field strongly suggests that there are two sources of local fields exerting coherently on muons in phase IV. It was inferred from the muon Knight shift under a transverse field that the direction of the effective internal magnetic field probed by muon exhibits a marked change between phase III and IV.
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  • Hiroshi Ezawa
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 35-42
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    For a given field V(x) on the x-axis, we shall find out the exponent ν such that X[ω] = 1/Tν0TV (ω(t))dt has, in the limit T → ∞, a non-trivial statistical distribution, and also the distribution itself, where ω(t) is the Brownian motion. The exponent ν turns out to be 1/2 when ∫-∞ V(x) dx is nonvanishing, and 1/4 when vanishing. The distributions are independent from the starting point of the Brownian motion. The result is relevant to the physics of chemoreception when the Brownian wanderer is identified with a bacterium or other small organism.
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  • Faqir M Bhatti, Nur Azman Abu
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 43-48
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Let F(G) be any additive property of a simple graph such that F(G)=F(G1)+F(G2), where G is the series combination of graphs G1 and G2. The weight factor W(G) which is based on F(G) arises in the low-density series expansion techniques for percolation models as W(G)=∑G⊆ G(-1)e-eF(G)η(G), where η(G) is the indicator that G cover-able sub-graph or without dangling ends. The purpose of this paper is to prove the weight factor formula for additive property of F as W(G)=d(G2)W(G1)+d(G1)W(G2), where d(G1) are d(G2) the d-weight for graphs G1 and G2 respectively. This result will be more simplified in the case of Directed Percolation Models using Mobius function property. A new few formulas for the resistive weight factors are also derived for a graph, which is parallel combination of n edges.
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  • Ken Kiyono, Nobuko Fuchikami
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 49-55
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Using a mass-spring model, we study a periodically forced dripping faucet as an example of nonfeedback control systems. The model is confirmed to exhibit entrainment from chaotic to periodic motion by adding an external force, which has been observed experimentally. It is found from an analysis of a two-dimensional Poincaré map that a discontinuous change between chaotic and periodic motion occurs via global bifurcations including a homoclinic bifurcation and a homoclinic tangency crisis. A hysteresis of the transition point is also explained. A possible way of suppressing chaos in the dripping faucet system by periodic forcing is suggested from the mass-spring model, which is also supported by a corresponding fluid dynamical simulation.
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  • Akira Shimizu, Takayuki Miyadera
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 56-59
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We study spatial correlation functions of local operators of interacting many bosons confined in a box of a large, but finite volume V, for various `ground states' whose energy densities are almost degenerate. The ground states include the coherent state of interacting bosons (CSIB), the number state of interacting bosons (NSIB), and the number-phase squeezed state of interacting bosons, which interpolates between the CSIB and NSIB. It was shown previously that only the CSIB is robust (i.e., decoheres much more slowly than the other states) against the leakage of bosons into an environment. We show that for the CSIB the spatial correlation of any local operators A(r) and B(r') (which are localized around r and r', respectively) vanishes as |r - r' | ∼ V1/3 → ∞, i.e., the CSIB has the `cluster property.' In contrast, the other ground states do not possess the cluster property. Therefore, we have successfully shown that the robust state has the cluster property. This ensures the consistency of the field theory of bosons with macroscopic theories.
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  • Hirohito Kiwata
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 60-66
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We investigate effect of external flow on domains in two-dimensional phase-separating binary fluid. By use of the coupled Cahn-Hillard and Navier-Stokes equations, we study stability of a lamellar domain under two-dimensional Poiseuille flow within a linear stability analysis. We derive stability eigenvalues for long wavelength fluctuations. The two-dimensional Poiseuille flow has the effect of mixing a stable zigzag mode and an unstable varicose mode so that they both become stable. The width of the stable lamellar domain depends on a distance from wall.
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  • Kazuo Fujikawa
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 67-74
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We comment on a formulation of quantum statistical mechanics, which incorporates the statistical inference of Shannon. Our basic idea is to distinguish the dynamical entropy of von Neumann, H = -k Tr ˆρlnˆρ, in terms of the density matrix ˆρ(t), and the statistical amount of uncertainty of Shannon, S= -k ∑npnln pn, with pn=‹ n|ˆρ|n› in the representation where the total energy and particle numbers are diagonal. These quantities satisfy the inequality S≥ H. We propose to interprete Shannon's statistical inference as specifying the initial conditions of the system in terms of pn. A definition of macroscopic observables which are characterized by intrinsic time scales is given, and a quantum mechanical condition on the system, which ensures equilibrium, is discussed on the basis of time averaging. An interesting analogy of the change of entroy with the running coupling in renormalization group is noted. A salient feature of our approach is that the distinction between statistical aspects and dynamical aspects of quantum statistical mechanics is very transparent.
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  • Hiroyuki Furukawa, Tsuguo Takahashi
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 75-80
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The steady secondary flow around a circular cylinder oscillating rotationally about its axis in a uniform flow is investigated with the successive approximation based on the Oseen approximation. The equations for the secondary flow are derived analytically. Numerical solutions to these equations are obtained by using the solutions to the Oseen equations. It is shown that the steady streaming directs to the upstream and that the fluid velocity becomes slow as the frequency of the oscillation is increased. The drag due to the steady streaming is also obtained from numerical results and shown to take negative values at high frequencies of oscillation.
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  • Yosuke Yamazaki, Yukio Kaneda, Robert Rubinstein
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 81-92
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The dynamics of the inviscid truncated system of rotating turbulence is studied by numerical simulations under various initial conditions and rotation rates. The simulations suggest that the rotating inviscid truncated system ultimately relaxes towards an equipartition state with energy isotropically distributed at all scales of motion regardless of the initial conditions. Rotation delays relaxation to equipartition in a strongly scale-dependent and anisotropic manner. There is some transient tendency to two-dimensionalize an initially isotropic non-equilibrium state and to maintain initially quasi-two-dimensional initial conditions. Both trends are enhanced by increasing the rotation rate.
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  • Naohiro Kasuya, Kimitaka Itoh, Yuichi Takase
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 93-98
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Various types of peaked structure in the radial electric field are predicted theoretically in edge biasing experiments using electrodes. A nonlinear diffusion equation is employed to describe the radial electric field, and is solved in the region bounded by electrodes. Structures with multiple peaks are allowed when the distance between electrodes is finite. The minimum value for the distance between electrodes is obtained. The distance between electrodes, the externally driven current and the applied voltage determine the number of solutions. Multiple transitions and hysteresis are predicted from the relationship between the voltage and the current.
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  • Komajiro Niizeki, Nobuhisa Fujita
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 99-118
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    One-dimensional quasilattices are classified into mutual local-derivability (MLD) classes on the basis of geometrical and number-theoretical considerations. Most quasilattices are ternary, and there exist an infinite number of MLD classes. Every MLD class has a finite number of quasilattices with inflation symmetries. We can choose one of them as the representative of the MLD class, and other members are given as decorations of the representative. Several MLD classes of particular importance are listed. The symmetry-preserving decorations rules are investigated extensively.
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  • Kozo Hoshino, Fuyuki Shimojo, Shuji Munejiri
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 119-124
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The atomic dynamics of liquid Ge, Sn and Na are studied based on the mode-coupling theory. The memory functions for the velocity autocorrelation functions (VAF) are obtained for liquid Ge, Sn and Na numerically from the VAF obtained by the molecular-dynamics simulations and are divided into the binary-collision term and the mode-coupling term. For the liquid Na the memory functions are also calculated theoretically by the mode-coupling theory and compared with that obtained numerically. The characteristic features of the memory functions for the liquid Ge and Sn near the triple point are qualitatively different from those for the typical liquids and are similar to those of the memory function of the liquid Na at high temperatures, which cannot be described by the mode-coupling theory.
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  • Hideoki Murakami, Mizuka Sano
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 125-126
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Positron lifetime spectra for multiwall carbon nanotubes doped with the alkali metals, K, Rb and Cs, are found to consist of a single component with a lifetime of 0.36 ns at 280 K, independent of the alkali metal. The shorter lifetime than in pristine carbon nanotubes (0.382 ns) demonstrates positron annihilation at a site of higher electron density. We conclude that all positrons injected into alkali metal-doped carbon nanotubes annihilate at positron-trapping centers, derived probably from extended lattice defects located on their negatively-charged graphitic shells.
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  • Daisuke Imagawa, Hikaru Kawamura
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 127-140
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Spin and chirality orderings of the three-dimensional Heisenberg spin glass under magnetic fields are studied by large-scale equilibrium Monte Carlo simulations. It is found that the chiral-glass transition and the chiral-glass ordered state, which are essentially of the same character as their zero-field counterparts, occur under magnetic fields. The chiral-glass ordered state exhibits a one-step-like peculiar replica-symmetry breaking in the chiral sector, while it does not accompany the spin-glass order perpendicular to the applied field. Critical perperties of the chiral-glass transition are different from those of the standard Ising spin glass. Magnetic phase diagram of the model is constructed, which reveals that the chiral-glass state is quite robust against magnetic fields. The chiral-glass transition line has a character of the Gabay-Toulouse line of the mean-field model, yet its physical origin being entirely different. These numerical results are discussed in light of the recently developed spin-chirality decoupling-recoupling scenario. Implication to experimental phase diagram is also discussed.
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  • L. T. Kong, J. B. Liu, B. X. Liu
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 141-143
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    In the equilibrium immiscible Y-Nb system, the total energies of the possible structures for Y3Nb and YNb3 non-equilibrium phases were calculated as a function of their lattice constant(s), under the frame work of the Vienna ab initio simulation package (VASP) and the calculated results predicted the relative stability of the Y3Nb and YNb3 phases crystallizing in four possible simple structures, i.e. A15, D019, L12 and L60 structures, respectively. Experimentally, a fcc Y3Nb non-equilibrium phase was indeed obtained by ion beam mixing and its lattice constant determined by diffraction analysis was in agreement with the calculated value.
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  • Keiji Itoh, Kenji Maruyama, Masakatsu Misawa, Shigeru Tamaki
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 144-147
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The diffusion constants of both cation and anion in liquid Cu2Se have been measured based on the time dependence of decaying residual potential due to the charge polarization after the turning-off of applied current. The experimental decaying curves were fitted by three exponential terms. Two terms correspond to the diffusion process of copper and selenium ions, respectively, and the rest is attributed to a relaxation of electronic polarization. It is found that the temperature dependences of diffusion constants of copper and selenium ions are negligibly small, on the other hand, the relaxation time of electronic polarization increases with increasing temperature.
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  • Toyohiko Kinoshita, Heralu Pathirannehelage Nihal Jayalath Gunasekara, ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 148-155
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The resonant photoemission spectra and X-ray absorption spectra of temperature-induced valence transition material EuNi2(Si1-xGex)2 around Eu 3d-4f, 4d-4f and Ni 2p-3d resonant excitation regions have been measured. From the comparison between the resonant photoemission spectra around the 3d-4f (bulk sensitive) and 4d-4f (surface sensitive) excitation regions, the Eu divalent component originating from the surface is separated from the bulk one. The divalent and the trivalent features of 4f electrons are obviously distinguished depending on the excitation conditions. It was confirmed that the intensity ratio of the 4f electronic structures between the Eu divalent and trivalent ions changes as a function of the temperature. The mean valence values estimated from the Eu M-edge X-ray absorption spectra and from the photoemission spectra were rather smaller than those obtained previously from the L-edge X-ray absorption spectra. The reason of the discrepancy is discussed. The spectral features and the resonant behaviors are well explained by a theoretical calculation based on the atomic model except for the strong contribution from the Ni 3d bands. In the resonant condition of the Eu divalent component, the spin flip satellite beside the 4f divalent states was observed. The photoemission spectra around the Ni 2p-3d excitation region show similar behavior to that of Ni pure metal.
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  • Hiroyoshi Ishii, Kenji Obu, Motoki Shinoda, Chol Lee, Yasuhiro Takayam ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 156-161
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We have measured the Pr 4d-4f high-resolution resonant photoemission and the Pr 3d core-level photoemission spectra of PrFe4P12 and related compounds PrSn3, PrAl2 and Pr metal. The Pr 4f and Pr 3d spectra of PrFe4P12 show the spectral features corresponding to a strongly hybridized system in Pr compounds. However, the 3H4 state located just below the Fermi energy is observed as a shoulder instead of the prominent peak expected for the strongly hybridized or high-Kondo temperature systems. From the analysis of the Pr 3d core-level spectrum, we infer that the absence of the peak structure near the Fermi energy reflects the weak hybridization strength between the Pr 4f and the valence band states at the Fermi energy.
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  • Hiroaki Shishido, Rikio Settai, Dai Aoki, Shugo Ikeda, Hirokazu Nakawa ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 162-173
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We have studied Fermi surface properties of LaRhIn5 and CeTIn5 (T: Co, Rh and Ir) via the de Haas-van Alphen (dHvA) experiment. The Fermi surface of a non-4f reference compound LaRhIn5 is quasi-two dimensional, reflecting the unique tetragonal crystal structure, which is consistent with the result of FLAWP energy band calculations. The Fermi surface of an antiferromagnet CeRhIn5 is similar to that of LaRhIn5, although the cyclotron mass in CeRhIn5 is roughly by one order larger than that in LaRhIn5. Both Fermi surfaces are, however, different from those of CeCoIn5 and CeIrIn5 which are well explained by the 4f-itinerant band model. The 4f electrons in CeRhIn5 thus do not contribute to the volume of the Fermi surface. We have also studied magnetic and superconducting properties of CeCoIn5 and CeIrIn5.
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  • Kaoru Iwano
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 174-178
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    It has been argued theoretically that a new state, namely, no halogen displacements around Pd ions and, consequently, their trivalent states with finite magnitudes of spin, will be realized by at least 50%-inclusion of Ni ions in Pd-Ni mixed-metal MX-chains. This state is peculiar to such mixed-metal systems, because it is never found as a ground state for homo-metal chains of Pd. Moreover, from the theoretical viewpoint, strong electron-lattice interaction and strong electron-electron Coulombic repulsion are mixed up to give a very interesting example for the study of both. Here we go beyond the previous theoretical work that was based on a Hartree-Fock (HF) calculation and investigate the same system by a quantum Monte-Carlo method applied to a Peierls-Hubbard model. The obtained result is qualitatively the same as the previous one and therefore reinforces the above interpretation with a preliminary result for magnetic susceptibility. Moreover, we show statistically averaged lattice states for rather continuous composition changes, within the framework of HF calculations. The obtained result explains well the Raman data.
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  • Eiji Tsuchida, Kiyoyuki Terakura
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 179-182
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We present an enhanced extrapolation scheme which provides significantly improved initial guesses for the wavefunctions in the first-principles calculations. Since the method is based on the population analysis, Mulliken charges are also obtained with minor additional computational efforts.
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  • Katsunori Kubo, Dai S. Hirashima
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 183-188
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Orbital orderings in ferromagnetic metallic manganites are studied. We study a model which describes the perovskite manganites in the ferromagnetic metallic phase at absolute zero by the mean field theory and by the self-consistent second order perturbation theory. Although various orbital ordered states are obtained by the mean field theory as in the previous studies, we find that no orbital ordered states with two-sublattice structures are stable in the ferromagnetic metallic phase when we take proper account of the electron correlation effect.
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  • Shoji Yamamoto, Masanori Ichioka
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 189-196
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Motivated by recent stimulative observations in halogen (X)-bridged binuclear transition-metal (M) complexes, which are referred to as MMX chains, we study solitons in a one-dimensional three-quarter-filled charge-density-wave system with both intrasite and intersite electron-lattice couplings. Two distinct ground states of MMX chains are reproduced and the soliton excitations on them are compared. In the weak-coupling region, all the solitons are degenerate to each other and are uniquely scaled by the band gap, whereas in the strong-coupling region, they behave differently deviating from the scenario in the continuum limit. The soliton masses are calculated and compared with those for conventional mononuclear MX chains.
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  • Eiji Tsuchida
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 197-203
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We show how to adapt the quasi-Newton method to the electronic-structure calculations using systematic basis sets. Our implementation requires less iterations than the conjugate gradient method, while the computational cost per iteration is much lower. The memory usage is also quite modest, thanks to the efficient representation of the approximate Hessian.
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  • Shinkichi Horie, Akira Suzuki
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 204-210
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We have studied the effect of constrictions on the conductance of ballistic quantum wires having double constrictions. Unlike the ideal quantum wires with no constriction, the conductance of these double constricted quantum wires shows peak and dip structures in quantized conductance steps for both symmetric and asymmetric cases. The origin of these dip and peak structures seen in the conductance steps are clarified for these symmetric and asymmetric systems by mode coupling analysis.
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  • Yoshihide Tanaka, Akira Oguri, Hiroumi Ishii
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 211-221
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We study the effects of electron correlation on transport through an interacting region connected to multi-mode leads based on the perturbation expansion with respect to the inter-electron interaction. At zero temperature the conductance defined in the Kubo formalism can be written in terms of a single-particle Green's function at the Fermi energy, and it can be mapped onto a transmission coefficient of the free quasiparticles described by an effective Hamiltonian. We apply this formulation to a two-dimensional Hubbard model of finite size connected to two noninteracting leads. We calculate the conductance in the electron-hole symmetric case using the order U2 self-energy. The conductance shows several maximums in the U dependence in some parameter regions of ty/tx, where tx (ty) is the hopping matrix element in the x- (y-) directions. This is caused by the resonance occurring in some of the subbands, and is related with the U dependence of the eigenvalues of the effective Hamiltonian.
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  • Yoshio Miura, Hideaki Kasai, Wilson Agerico Diño, Ayao Okiji
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 222-227
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We investigate and discuss the dynamics of H abstraction from Cu(111) by performing quantum dynamics calculations. We introduce a new theoretical approach that considers both quantum mechanically direct (the impinging H directly abstracts an adsorbed H) and indirect (the impinging H diffuses across the surface before it abstracts an adsorbed H) processes for H abstraction, and investigate how the coverage of adsorbed H on Cu(111) affects the vibrational and surface-parallel translational energy distribution of product H2. We expect that the H abstraction dynamics would depend on the coverage, because the shape of the corrugation depends on the coverage. Our results, for the case when the kinetic energy of the incident H Et=0.1 eV, confirm this expectation. The mean vibrational energies of product H2 decrease with decreasing coverage. On the other hand, the mean surface-parallel translation energies of product H2 increase with decreasing coverage. These results indicate that for the low coverage case, H abstraction occurs mainly through the indirect process, where the vibrational excitation of product H2 is suppressed, and the excitation for the surface-parallel translational motion of product H2 is enhanced, as compared with those for the high coverage case, where the H abstraction can occur through both direct and indirect processes.
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  • Hiroshi Akera
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 228-236
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Hydrodynamic equations (HDEQs) are derived which describe spatio-temporal evolutions of the electron temperature and the chemical potential of two-dimensional systems in strong magnetic fields in states with large diagonal resistivity appearing at the breakdown of the quantum Hall effect. The derivation is based on microscopic electronic processes consisting of drift motions in a slowly-fluctuating potential and scattering processes due to electron-electron and electron-phonon interactions. In contrast with the usual HDEQs, one of the derived HDEQs has a term with an energy flux perpendicular to the electric field due to the drift motions in the magnetic field. As an illustration, the current distribution is calculated using the derived HDEQs.
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  • Yunori Nisikawa, Kosaku Yamada
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 237-244
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We investigate the superconducting mechanism and the transition temperature of heavy fermion superconductor UPd2Al3 on the basis of a single band two-dimensional Hubbard model on triangular lattice, which represents the most heavy band of UPd2Al3. Both normal and anomalous self-energies are calculated up to third order with respect to the Coulomb repulsion U between itinerant electrons. The superconducting transition temperature is obtained by solving the Éliashberg's equation. Reasonable transition temperatures are obtained for moderately large U. It is found that the momentum and frequency dependence of spin fluctuations given by RPA-like terms gives rise to the d-wave pairing state, while the vertex correction terms are important for obtaining reasonable transition temperatures. These results seem to show that the superconductivity in UPd2Al3 can be explained by the perturbation theory with respect to U.
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  • Hideharu Ishida, Hiroto Adachi, Ryusuke Ikeda
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 245-253
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The position Bvg of a field-tuned superconductor-insulator quantum transition occuring in disordered thin films is examined within the mean field approximation and starting from a hamiltonian of BCS type (favoring the s-wave pairing) with a random potential, and effects of an electron-electron repulsion on the transition field Bvg are also considered. Our calculation shows that the (microscopic) disorder-induced reduction of Bvg suggested experimentally cannot be explained without taking account of the familiar interplay between the randomness and the electron-electron repulsion enhancing the quantum superconducting fluctuation in such systems.
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  • Hideharu Ishida, Ryusuke Ikeda
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 254-264
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Resistive behaviors at nonzero temperatures (T > 0) reflecting a quantum vortex-glass (VG) transition (the so-called field-tuned superconductor-insulator transition at T=0) are studied based on a quantum Ginzburg-Landau (GL) action for a s-wave pairing case containing microscopic details. The ordinary dissipative dynamics of the pair-field is assumed on the basis of a consistency between the fluctuation conductance terms excluded from GL approach and an observed negative magnetoresistance. It is shown that the VG contribution, Gvg, to 2D conductance becomes insensitive to T at an apparent VG transition field Bvg* defined at experimentally accessible temperatures but depends on the repulsive electron-electron interaction, and that, only in the dirty limit with no electron-repulsion, it takes a universal value at low T. Available resistivity data near Bvg* are explained based on our results, and an extension of the theory to 3D case is briefly discussed.
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  • Masafumi Ito, Hiroshi Harashina, Yukio Yasui, Masaki Kanada, Satoshi I ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 265-270
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Detailed structure of the magnetic excitation spectra χ′′(q,ω) of the superconducting oxide YBa2Cu3O6.5 (the transition temperature Tc≅ 52 K) in the wave vector (q)- and the energy(ω)-space, and its temperature (T) dependence have been studied. By adopting an effective energy dispersion of the quasi particles which can reproduce the shape of the Fermi surface and by introducing the exchange interaction between the Cu spins, a rather satisfactory agreement between the calculation and the experimentally observed data can be obtained. In the study, it has been found that the effects of the quasi particle-energy broadening on the excitation spectra χ′′(q,ω) is important. The sharp resonance peak observed at ω ∼ 40 meV for the optimally doped system of YBa2Cu3Oy can be naturally reproduced by the present model.
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  • Yukio Tanaka, Hiroki Tsuchiura, Yasunari Tanuma, Satoshi Kashiwaya
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 271-277
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Influences of magnetic field on tunneling conductance spectra in normal metal/dx2-y2-wave superconductor junctions are studied on the basis of the quasiclassical Green's function method where the spatial dependence of the pair potential is determined self-consistently. Focuses are set on the field response of the zero-bias conductance peaks (ZBCP). For the detection of the splitting of the ZBCP due to broken time-reversal symmetry states, we found the presence of a critical value for the magnetic field strength in contrast to previous theories. The critical field HC is almost proportional to the width of ZBCP in the absence of field and equivalently to the transparency of the junctions. The present result may explain the origin for the inconsistency of the magnetic field responses in several experiments.
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  • Youichi Yanase
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 278-292
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    We investigate the electric transport in the pseudogap state of High-Tc cuprates. Starting from the repulsive Hubbard model, we perform the microscopic calculation to describe the pseudogap phenomena which are induced by the superconducting fluctuations. The single particle Green function, spin susceptibility and superconducting fluctuations are self-consistently determined by the SC-FLEX+T-matrix approximation. The longitudinal and transverse conductivities are calculated by using the Éliashberg and Kohno-Yamada formalism. The effects of the spin fluctuations and superconducting fluctuations are estimated, respectively. The vertex corrections arising from the two fluctuations are also calculated. The complicated relations between the various effects are discussed in details. The additional contribution from the Aslamazov-Larkin term is also estimated beyond the Éliashberg formalism. It is shown that the main effect of the superconducting fluctuations is the feedback effect through the spin fluctuations. Therefore, the correct results are obtained by considering the superconducting fluctuations and the spin fluctuations simultaneously. As a result, the temperature and doping dependences of the resistivity and the Hall coefficient are explained. We point out that the characteristic momentum dependence of the systems plays an essential role in this explanation.
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  • Kotaro Yamada, Seiji Higashitani, Katsuhiko Nagai
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 293-299
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Rough surface effect on the Meissner diamagnetic current in the normal layer of proximity contact N-S bi-layer is investigated in the clean limit. The diamagnetic current and the screening length are calculated by use of quasi-classical Green's function. We show that the surface roughness has a sizable effect, even when a normal layer width is large compared with the coherence length ξ =vF/π Tc. The effect is as large as that of the impurity scattering and also as that of the finite reflection at the N-S interface.
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  • Tetsuya Kato
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 300-307
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Single-crystal X-ray and neutron diffraction study of the distorted-triangular-lattice antiferromagnet RbMnBr3 was carried out in order to clarify the crystal structure below T4∼ 222 K (phase V) and to find the origin of spin arrangement below TN=8.5 K. The phase-V diffraction pattern showed some systematic and accidental extinction of possible reflections with triple-domain formation. An orthorhombic structure of a space group symmetry Pbca with a unit cell 2a0×√3a0× c0 (Z=8) was proposed. The triangular lattice of Mn2+ ions is distorted in a novel form, coined as a zigzag-row model. Spin arrangement of this model was deduced using the mean-field theory. Spin structures of RbMnBr3 in the incommensurately modulated LT (low-field triangular) and the commensurately modulated HT (high-field triangular) phases are described.
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  • Takaaki Tanaka, Hiroaki Ishida, Masayuki Matsumoto, Shinji Wada
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 308-312
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The electronic and magnetic states of a pseudo one-dimensional (1D) antiferromagnet LiCuVO4 (TN=3.3 K), which consists of distorted CuO6 linear chains, have been investigated microscopically with nuclear magnetic resonance measurements. The characteristic of the 1D antiferromagnetic (AF) spin=1/2 chains appears in a broad extremum of the resonance shift K for each of 65Cu, 51V and 7Li at the temperatures around TM=28 K, which can reasonably be compared with the Bonner-Fisher-type behavior of the susceptibility χ. From the linear dependence of K on χ, the hyperfine field for each of 65Cu, 51V and 7Li is estimated as ∼20, 5.6 and -0.25 kOe/μB, respectively, indicating that the magnetism originates from Cu2+ ions on the octahedral B sites. The nuclear spin-lattice relaxation rate T1-1 of 51V on the tetrahedral A sites has somewhat complex temperature dependence, which can not simply be explained by the scaling theories for the standard AF spin=1/2 chain. A broad T1-1 maximum observed around 80 K and an upturn below ∼15 K are ascribed to the development of 1D and 2D or 3D AF short-range orderings at rather high temperatures well above TM and TN, respectively.
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  • Masaki Kanada, Yukio Yasui, Yasuyuki Kondo, Satoshi Iikubo, Masafumi I ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 313-318
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Intensity distribution of the neutron magnetic scattering has been taken in the reciprocal space of a single crystal of the “spin ice” system Ho2Ti2O7 at the elastic energy position in the temperature (T) region between 0.4 K and 50 K. The short range magnetic correlation becomes appreciable with decreasing T at around 30 K. The freezing of the moment system takes place at around 1.5 K with decreasing T. Based on the mean field treatment of the moment system, the distribution of the observed intensity has been reproduced, where the dipolar interaction is confirmed to be primarily important for the determination of the magnetic correlation. Simple calculations of the scattering intensity carried out by using a cluster of 25 moments of Ho3+ ions indicate that there are many types of the moment arrangement within a cluster which have almost degenerated energies, indicating that the system cannot uniquely select the correlation pattern down to rather low temperature, and before going to the lowest energy state, the system undergoes the gradual slowing down to the glassy state.
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  • Toshiya Hikihara
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 319-325
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    The ground-state phase diagram of a frustrated S = 1 Heisenberg spin chain with uniaxial single-ion-type anisotropy is studied using the infinite-system density-matrix renormalization-group method. Particular attention is paid to “chiral” phases, in which the long-range order parameter is a vector chirality. It is found that, in addition to the Haldane, large-D (LD), and double-Haldane phases, the phase diagram includes three different chiral phases, i.e., the gapless chiral, chiral-Haldane, and chiral-LD phases. These chiral phases are distinguished from each other by the energy gap and the string long-range order.
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  • Kiyohiro Sugiyama, Tomoya Iizuka, Dai Aoki, Yoshifumi Tokiwa, Kousaku ...
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 326-331
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    UX3 (X=Si, Ge, Sn and Pb) compounds with the cubic crystal structure are interesting in relation with the lattice constant and the electronic state of 5f electrons.We measured the high-field magnetization of USn3 and UPb3 grown by the self-flux method.The broad metamagnetic transition was observed in a heavy fermion paramagnetic compound USn3 at about 30 T, which is similar to the metamagnetism of UPt3. On the other hand, the sharp metamagnetic transitions were observed in an antiferromagnetic compound UPb3.
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  • Ae Ran Lim, Jae Kap Jung, Se Young Jeong
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 332-335
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Magnetic susceptibility and paramagnetic shift for central transition of 133Cs NMR in the single crystal CsCuCl3 which has transition temperature TN=10.5 K have been measured in the temperature range of 4.2-300 K. From experimental result, we have obtained the transferred hyperfine interaction due to the transfer of spin density from the Cu2+ ion to the Cs+ ion in CsCuCl3 single crystal. The transferred hyperfine interaction can be expressed by the linear equation Hhf=[3.54 T+2.84] (Oe) in the temperature range of 50-300 K; the Hhf increases with increasing temperature. 133Cs spin-lattice relaxation time of 133Cs NMR in the CsCuCl3 single crystal was also measured in the same temperature range. The temperature dependence of 1/T1 is nearly constant in the paramagnetic phase, while relaxation rate near TN exhibits remarkable change, indicating a drastic alternation of spin dynamics at the Neel temperature.
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  • Fumiyuki Ishii, Tamio Oguchi
    Article type: General Physics
    Subject area: Mathematical methods in physics.
    2002 Volume 71 Issue 1 Pages 336-339
    Published: 2002
    Released on J-STAGE: April 25, 2003
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    Ferroelectricity in sodium nitrite NaNO2 has been studied from first principles. The spontaneous polarization calculated with Berry-phase theory is 0.116 C/m2, being in excellent agreement with experimental values, 0.117 C/m2 and 0.119 C/m2. In order to discuss the phase transitions, we have estimated coupling parameters J1 and J2 in the axial next-nearest-neighbor Ising model from total-energy and force calculations. As results, J1 and J2 are quite sensitive to relative displacement of NO2 molecules. The transition temperature and a role of molecular displacement in the phase transitions are discussed in detail.
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