Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 55, Issue 8
Displaying 1-50 of 62 articles from this issue
  • Yoshinori Hayakawa, Hiroshi Kondo, Mitsugu Matsushita
    1986 Volume 55 Issue 8 Pages 2479-2482
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Two-dimensional Monte Carlo simulations are performed for the generalized diffusion-limited aggregation (DLA) model which is equivalent to the dielectric breakdown model proposed by Niemeyer et al. It is found that the simulated patterns are self-similar, and the fractal dimensions of these patterns agree well with the theoretical formula, df={ds2+η(dw−1)}⁄{ds+η(d2−1)}, derived by Matsushita et al., where ds is the spatial dimension, dw the fractal dimension of the random-walker trajectory, and η an exponent contained in the local growth probability at the perimeter site. Further, our simulation results suggest that effect of lattice anisotropy becomes prominent when increasing the exponent η.
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  • Mitsugu Matsushita, Hiroshi Kondo
    1986 Volume 55 Issue 8 Pages 2483-2486
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    A new approach is proposed to enhance the effect of lattice anisotropy on diffusion-limited aggregation (DLA) model. The computer simulations on the square lattice clearly show the morphological change of overall profile of the patterns from random fractal to more or less regular dendritic crystal-like and finally to needle crystal-like “cross” shapes. This implies the close relationship between DLA and real dendritic crystal growth.
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  • Haruo Honjo, Shonosuke Ohta, Mitsugu Matsushita
    1986 Volume 55 Issue 8 Pages 2487-2490
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Irregular dendritic crystals of ammonium chloride (NH4Cl) are grown two-dimensionally between two parallel glasses, one of which has rough surface. The pattern clearly reminds us of those of Witten-Sander diffusion-limited aggregation (DLA) model. The radius of gyration is measured to give the fractal dimension df=1.67±0.002, which is in good agreement with two-dimensional DLA. Our result implies that any random perturbations strong enough to overcome crystalline anisotropy always give rise to random DLA-like crystals, instead of otherwise regular dendritic crystals.
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  • Keishi Ishii, Hirotaka Kubo, Tadahiko Onoyama, K\={o}ichi Takayama
    1986 Volume 55 Issue 8 Pages 2491-2493
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    This paper presents measurement of polarized photon emission from the foil-excited 4He+ ion in an external static electric field parallel to the ion beam. Strong asymmetry was observed when the direction of the external field is reversed. The result is interpreted in terms of coherent superposition of excited states of opposite parity.
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  • Tsutomu Kambe
    1986 Volume 55 Issue 8 Pages 2494-2495
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Based on the theory of aerodynamic sound in the presence of a solid body, it is found that the force on the body exerted by a system of loop vortices is represented by a linear combination of an individual integral for each vortex, and that the integral is reduced to the time derivative of a volume flux J (through the vortex loop) of a hypothetical potential flow around the body. The second time derivative of J gives the amplitude of the dipolar sound wave excited by the vortex motion.
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  • Toshiaki Makabe
    1986 Volume 55 Issue 8 Pages 2496-2499
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    The effects of the mass ratio mM on the swarm parameters are investigated in the case of a constant collision frequency model. Here, m and M are the masses of a charged particle and a neutral molecule, respectively. Expressions for the swarm parameters are derived from the simple kinetic theory without use of a complicated stochastic equation, i.e., Boltzmann equation. Present theoretical results are shown to be in remarkable agreement with those of the recent simulation by Ikuta et al.
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  • Katsuhisa Koura
    1986 Volume 55 Issue 8 Pages 2500-2503
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The Monte Carlo simulation (MCS) of the electron swarm in a model gas with the momentum-transfer cross section of the form σm(ε)∝εγ (γ=−0.5, 0, and 1), ε being the electron energy, is carried out in order to investigate the recent question raised, in particular, for γ=1 about the conventional two-term expression for the transverse diffusion coefficient DT. The MCS results confirm that the two-term solution of DT (and other swarm parameters) is sufficiently accurate even for γ=1 contrary to the recent doubt; a possible reason for the discrepancy previously revealed between the MCS and two-term values of DT is suggested. The scaling rule for the electron swarm in rare gases derived on the basis of the two-term approximation of the Boltzmann equation in order to reduce the MCS computation time is verified to be valid.
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  • Yoshimitsu Amagishi
    1986 Volume 55 Issue 8 Pages 2504-2507
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    Signals due to the change of diamagnetic pressure of the plasma have been measured to demonstrate the plasma heating by the axisymmetric fast (compressional) wave which is launched toward a region of increasing magnetic field. As expected from our previous experiment concerning the conversion of the fast wave into the ion cyclotron wave in a cylindrical plasma, a remarkable increment of the diamagnetism has been observed for the first time near the ion cyclotron resonance area.
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  • Hideaki Kasai, Satoru Enomoto, Ayao Okiji
    1986 Volume 55 Issue 8 Pages 2508-2511
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    The vibrational state distribution of NO molecules scattered from Pt(111) surface is calculated in the framework of the kinetic theory of gas molecule-surface scattering. The experimental findings obtained by Asscher et al. are explained satisfactorily.
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  • Teruya Shinjo, Noriaki Nakayama, Isao Moritani, Yasuo Endoh
    1986 Volume 55 Issue 8 Pages 2512-2514
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    By alternately depositing Mn(1 Å) and Sb(60 Å), epitaxially grown MnSb monolayers in between Sb layers have been prepared. At 4.2 K, the MnSb monolayers exhibit ferromagnetic behavior and the easy direction is found to be perpendicular to the film plane.
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  • Seiichiro Suga, Hideaki Kasai, Ayao Okiji
    1986 Volume 55 Issue 8 Pages 2515-2518
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The effect of a magnetic impurity on the life time of the conduction electrons and on the conductivity in the weakly localized regime are investigated by the perturbational method in terms of exchange coupling constant J. It is shown that the corrections for those quantities are proportional to J3λd−1Td⁄2−2(1+2ρ0J ln εFT)−3 within the framework of the most divergent approximation, where d is the dimensionality and λ the degree of disorder.
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  • Sadao Takaoka, Fumiyuki Nihei, Kazuo Murase, Akihiro Ishida, Hiroshi F ...
    1986 Volume 55 Issue 8 Pages 2519-2522
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    An indication of the quantum Hall effect has been observed in the superlattice of PbTe-Pb0.78Sn0.22Te on BaF2 (111) substrate. The positions of steps in the Hall resistance are well explained, if the singlet (111) valley in the PbTe quantum well is unoccupied. Compressive strain in PbTe layers caused by the lattice mismatch between PbTe and PbSnTe layers raises the singlet valley higher than the other three valleys.
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  • Yoshimasa Isawa, Hiromichi Ebisawa, Sadamichi Maekawa
    1986 Volume 55 Issue 8 Pages 2523-2526
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    A theory of the conductance oscillation with flux period hce in a small normal metal ring with long leads is developed. We find that (i) the oscillation is strongly affected by leads, and (ii) the magnitude of the conductance fluctuations of the ring depends crucially on size and material of the ring and leads. The temperature dependence of the oscillation is consistent with experiments.
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  • Fusayoshi J. Ohkawa
    1986 Volume 55 Issue 8 Pages 2527-2530
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The residual resistivity of Kondo lattices is theoretically investigated. Randomness of ligands should play an important role, i.e., randomness of hybridization or conduction electron levels. It has been shown that randomness of renormalized f levels is small in the absence of magnetic fields, while it increases with increasing fields. Therefore a positive magnetoresistance is predicted at low temperatures.
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  • Shuichiro Anzai, Masanori Matoba, Masakazu Hatori, Hiroshi Sakamoto
    1986 Volume 55 Issue 8 Pages 2531-2534
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Hexagonal lattice parameters a and c of the NiAs-type NiS1−ySey expand with increasing y below the solubility limit yL=0.20. The first-order transition temperature Tt(y) [between the antiferromagnetic less-conductive and the Pauli-paramagnetic high-conductive states] decreases with increasing y, and is suppressed down to liq. He temperature at the critical concentration , yc=0.133. Just above Tt(y) the temperature slope of the susceptibility has positive sign at low y, and shows a y-dependence. The isothermal susceptibility of the Pauli-paramagnetic state decreases with increasing y. These experimental results are discussed on the basis of the strongly correlated features of d and p bands in NiS.
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  • Kouichi Ishiyama, Keizo Endo
    1986 Volume 55 Issue 8 Pages 2535-2538
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The occurrence of the weak itinerant ferromagnetism is found in the pseudobinary compound system Sc(Co1−xAlx)2 in the Al concentration range between x=0.15 and 0.30. The values of the moment and the Curie temperature TC are 0.085 μB/Co and 23.7 K respectively and then the Rhodes-Wohlfarth ratio results in 14 at x=0.23. The square of the spontaneous magnetization and the inverse of the magnetic susceptibility are linear functions of T4⁄3, which is consistent with the SCR theory. The magnetic properties are very similar to those of Y(Co1−xAlx)2 as a whole. One of the characteristics in this system is that the values of TC are always larger than those of Weiss temperature θ.
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  • Toshikazu Katayama, Hiroyuki Awano, Yoshikazu Nishihara
    1986 Volume 55 Issue 8 Pages 2539-2542
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    The wavelength dependence of polar magneto-optical Kerr rotation angle (θK) was measured in compositionally modulated multilayered films (CMF) composed of Co/Cu, Fe/Cu, Co/Au and Fe/Au systems. The value of θK is low and the shape of wavelength dependence is relatively flat in the CMF with modulation length less than nearly 20Å. However, a new θK peak appears at around λ=560 nm in Co/Cu and Fe/Cu CMF and around λ=500 nm in Co/Au and Fe/Au CMF with large modulation length. These wavelengths correspond to the absorption edge of Cu and Au metals, respectively.
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  • Hajime Shibata, Yuhji Tsujimi, Tomoyuki Hikita, Takuro Ikeda
    1986 Volume 55 Issue 8 Pages 2543-2546
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    Light scattering spectra of KDP in the x(yx)y geometry have been measured at hydrostatic high-pressures up to 4.7 kbar as functions of temperature in the frequency range ±5 cm−1. The spectra at high pressures clearly showed that the relaxation time decreases with increasing pressure.
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  • Shozo Takeno, Shigeo Homma
    1986 Volume 55 Issue 8 Pages 2547-2561
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Two non-trivial versions, S(un)−\ddotun=(g⁄2) sin (2un) and S(un)−\ddotun=0 with S(un)≡sin (un+1un)−sin (unun−1), of a sine-lattice (SL) equation S(un)−\ddotun=g sin un are studied. The latter is a new sort of nonlinear equation in which “sonic” π- and 2π-kinks arise from the sine-second difference S(un) rather than the on-site term sin (un) or sin (2un). In their bilinear operator form the former and the latter yielding π-kinks have much neater form than the SL equation. These two equations exhibit approximate, but well-defined, one-and multi-π-kink solutions having one-to-one correspondence to those of the sine-Gordon equation, thus possessing nearly integrable soliton properties for the π-kinks. A numerical calculation of one- and two-kink solutions is made to illustrate this for kinks of narrow width and/or high velocity.
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  • Teruo Miura, Tohru Kai
    1986 Volume 55 Issue 8 Pages 2562-2571
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    A correlation dimension of a strange attractor for a system of 3 disk-dynamos and K2 entropy of the chaotic motion are obtained. Furthermore, a method that gives a dimension from a small number of data points is devised and is checked by computer simulations. The method is applied to geomagnetic evolution for the Early Cretaceous and Late Jurassic and the dimension of a corresponding attractor is caluculated. The data is obtained from the model of Larson and Hilde who reanalized magnetic data observed in the Northwestern Pacific Ocean.
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  • Yutaka Toyozawa
    1986 Volume 55 Issue 8 Pages 2572-2580
    Published: August 15, 1986
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    The conceptual basis of statistical operator is analysed by comparing two different ways of introducing it in quantum mechanics–subsystem method and ensemble method. The one-to-one correspondence of the statistical operator to the physical state properly characterized is contrasted with the deficient degrees of freedom of the wave function. The paradoxical features of the Einstein-Podolsky-Rosen type thought experiment and of the reduction of wave-packet at observation can be dissolved in the reformulation of quantum mechanics in which the statistical operator, instead of the wave function, is primarily introduced as the fundamental quantity to describe the state.
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  • Kazuhiro Fukushima, Tomoji Yamada
    1986 Volume 55 Issue 8 Pages 2581-2585
    Published: August 15, 1986
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    Dynamical behaviors for sine-Gordon soliton pinned to the impurity are studied numerically by solving a set of ordinary differential equations which are derived from the sine-Gordon equation under the external periodic field with perturbation theory. Chaotic motion occurs through the sequence of period-doubling bifurcation. As the amplitude of the external force further increases, a crisis occurs and the intensity of the chaotic motion increases. Furthermore for larger external fields the soliton is dispinned and begins to propagate.
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  • Yohtaro Ueno
    1986 Volume 55 Issue 8 Pages 2586-2604
    Published: August 15, 1986
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    Layered and isotropic frustration models on a square lattice are studied in a systematic way from the viewpoint of seeing how frustrations affect ordering. Ordering is attributed to entropy gains, which is analysed introducing cluster (C) regions and entropy-yielding (S) regions. These local structures are closely related to excited states with the lowest energy, which is investigated through the configurations of unsatisfied bonds (or strings). Searching for the conditions for local coupling between C regions via a S region and then for global ordering we reach the same results on the ordering for the layered models as those obtained by Hoever et al. For some isotropic models as well as layered ones the temperature dependence of interface tension is calculated. The former models show re-entrant phenomena characteristic of this type of phase transitions. The symmetry of frustration configuration and its breaking are also discussed.
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  • Atsuo Kuniba, Yasuhiro Akutsu, Miki Wadati
    1986 Volume 55 Issue 8 Pages 2605-2617
    Published: August 15, 1986
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    It is shown that a k-state IRF model (σ=0, 1, …, k−1), with a condition k−2≤σijk on adjacent spins σi and σj, is exactly solvable for all k(k≥3). This proves the existence of a new hierarchy of solvable IRF models. It is also shown that the k-state IRF model is equivalent to a 3k-state solid on solid (SOS) model. Considering all the known results, it is predicted that for an arbitrary set of integers L and f(L≥0, f≥1) there exists a solvable IRF model with the hard core condition L≤σijL+f.
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  • Mitsugu Matsushita, Katsuya Honda, Hiroyasu Toyoki, Yoshinori Hayakawa ...
    1986 Volume 55 Issue 8 Pages 2618-2626
    Published: August 15, 1986
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    Diffusion-limited aggregation (DLA) model is generalized to incorporate the dielectric breakdown model proposed by Niemeyer et al., and the new simulation method is proposed. While a growing cluster is still in the diffusion (Laplace) field, the local growth probability at a perimeter site Pps of the cluster is now given by pg(Pps)∼|∇φ(Pps)|n, where φ(P) is the probability of finding at a point P a random walker launched far away from the cluster. Ordinary DLA corresponds to η=1. Based on the theory of DLA proposed by Honda et al., the fractal dimension df for this generalized DLA is derived as df={ds2+η(dw−1)}⁄{ds+η(dw−1)}, where ds is the dimension of space in which aggregation processes take place and dw is the fractal dimension of random walker trajectory. Both ds and dw are allowed to take any number larger than or equal to one. This formula is also applicable to Eden model (η=0) correctly, which means that the generalized DLA model naturally bridges a gap between ordinary DLA and Eden models.
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  • Kaoru Ohno, Yutaka Okabe
    1986 Volume 55 Issue 8 Pages 2627-2635
    Published: August 15, 1986
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    The two-dimensional half-plane Ising model is examined in the presence of the alternately layered exchange interactions or the alternate surface magnetic field. Special attention is paid to the effect of the frustration or the competing interactions on the free energy and the magnetization. Especially, the surface-layer magnetization is calculated exactly. For some conditions, after the onset of the magnetic ordering at bulk Tc, the surface-layer spontaneous magnetization is shown to decrease exponentially toward zero as T→0. These models offer examples of the reentrant phenomena at surfaces.
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  • Satoshi Nozawa, Yasuharu Kohyama, Tomohiro Kaneta, Kuniharu Kubodera
    1986 Volume 55 Issue 8 Pages 2636-2640
    Published: August 15, 1986
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    In view of current interest in the use of the reactions νe+de+p+p and \barνe+de++n+n for studying the solar neutrinos, it is desirable to obtain reliable estimates of the cross sections of these reactions. In order to evaluate the reliability of the existing estimates based on the impulse approximation, we have examined possible effects of exchange currents and found that the modification of the impulse approximation results due to the exchange currents is not larger than ∼6%.
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  • Michio Yamada
    1986 Volume 55 Issue 8 Pages 2641-2647
    Published: August 15, 1986
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    Weakly nonlinear stability theory of parallel flows is known to encounter a difficulty when it is applied to free shear layers, that is, the mean flow distortion induced by the disturbance does not satisfy the boundary conditions. A new formulation of the nonlinear stability theory of general parallel free flows is proposed by considering an initial value problem of a disturbance and taking a fast-time-dependence of the induced flows into account. In this formulation, a non-secular condition for the third-order-term gives the Landau equation and the difficulty concerning the mean flow distortion does not arise.
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  • Shunjiro Shinohara, Osamu Naito, Yoshio Ueda, Hiroshi Toyama, Kenro Mi ...
    1986 Volume 55 Issue 8 Pages 2648-2652
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    Plasma heating by ion Bernstein wave in the range of 2ωD\lesssimω\lesssim3ωD is investigated in deuterium dominant plasma of the TNT–A tokamak. The localized electron heating is observed at the harmonic (3ωD) and subharmonic (2.5ωD) resonance layers, while the electron heating on the whole plasma region is observed at ω=2ωD. It is also shown that the heating is efficient and heating layer is localized by ion Bernstein wave in comparison with fast magnetosonic wave.
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  • Yoichiro Furutani, Minoru Shigesada, Hiroo Totsuji
    1986 Volume 55 Issue 8 Pages 2653-2670
    Published: August 15, 1986
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    Within the framework of the density functional theory (DFT), we have computed numerically the effective potential of a partially ionized high-Z ion and the associated radial profile of the electron density for temperatures ranging from T=0 to high temperature regimes of several hundreds eV.
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  • Eiichi Yagi, Shiho Nakamura, Takane Kobayashi, Fumihisa Kano, Kenji Wa ...
    1986 Volume 55 Issue 8 Pages 2671-2675
    Published: August 15, 1986
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    By the channeling method using the nuclear reaction 1H(11B, α)αα, the lattice location of H in TaH0.07(α-phase) was determined at room temperature, and the effect of strain on the hydrogen location was investigated by introducing internal strains by thermal cycling that gives rise to precipitation and redissolution of the β-phase. It is concluded that hydrogen atoms are located at tetrahedral sites in the α-phase of a Ta–H system, and the location does not change by such thermal cycling. Compared with the previous results on H in V and Nb, the present result indicates that the hydrogen location in Ta is less sensitive to the strain than in V as in the case of Nb.
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  • Yukichi Taji, Terufumi Yokota, Tadao Iwata
    1986 Volume 55 Issue 8 Pages 2676-2686
    Published: August 15, 1986
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    The formation of an interstitial atom in graphite crystals is simulated by the molecular dynamic method, in which the characteristic point is that the effect of covalent bonds in hexagonal lattices is taken into account as the non-central force interaction. It is found that the interstitial atom rests at an asymmetric site in the hexagonal lattice, which is deviated from the symmetric site obtained in the elastic membranes model for the lamellar structure of graphites. This dynamic process is analyzed in detail. The self-energy and the migration energy of an interstitial atom are obtained as 1.28 eV and 0.01 eV, respectively. The increase of crystal volume due to an interstitial atom amounts to 3.32 atomic volume, which coincides with the experimental value fairly well.
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  • Masato Takahashi, Hiroo Horiuchi, Satoshi Kinoshita, Yutaka Ohyama, Ta ...
    1986 Volume 55 Issue 8 Pages 2687-2694
    Published: August 15, 1986
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    Structure function S(k, t) in process of phase separation was investigated by light scattering for polystyrene/poly(methylphenylsiloxane) mixtures to test the scaling law for S(k, t) in the late stage. For the critical composition, the structure function obeyed the scaling law of S(k, t)=km−3·S(kkm), where k is the wave number, km the wave number yielding the maximum intensity, and S(kkm) the scaled structure function independent of time t. However, S(k, t) for the off-critical composition gradually changed with t, becoming to have a broader peak, so that the scaling law was only approximately satisfied. The full-width at a half of the maximum intensity increased with increasing quench-depth, being almost the same for the critical and off-critical compositions at comparable quench-depths. The value of exponent h in the power law S(kkm)∝(kkm)h at kkm>1 was around 4 for the off-critical quench, in agreement with the Furukawa theory, while for the critical quench it was slightly larger than 4, but not as large as the theoretical value 6.
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  • Shuichi Hayase, Kazuya Kamon, Hirofumi Sakashita, Hikaru Terauchi
    1986 Volume 55 Issue 8 Pages 2695-2700
    Published: August 15, 1986
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    The measurements of thermal expansion in a random mixture of ferroelectric RbH2PO4(RDP) and antiferroelectric NH4H2PO4(ADP), (RDP)1−x(ADP)x, were made by X-ray diffraction. Anomalous expansion of lattice constants was observed in glassy (RDP)1−x(ADP)x(0.22<x<0.75) at low temperatures, while the crystal symmetry was still tetragonal. Temperature dependence of the anomalous expansion can be related to the idea of cluster condensation. The NH4-concentration dependence of the anomalous expansion implies that the glass is the mixture of two kinds of local strains at low temperatures.
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  • Mitsuto Fukuma, Satoshi Takada
    1986 Volume 55 Issue 8 Pages 2701-2715
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The collective coordinate method is applied to develop the statistical mechanics of soliton systems. The present perturbation expansion is a direct extention of that done in the quantum field theory and is applicable to the quantum case. A new type of divergence which has never met so far in the many body theory appears in the present treatment but it can be removed by an appropriate treatment giving reasonable results. As the first paper of this series the classical case is investigated and explicit calculation is done in the classical sine-Gordon model. The results agree with the exact low temperature corrections obtained by the transfer-integral method and with those obtained by Miyashita and Maki who applied the collective coordinate approach in a different way.
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  • Takao Nanba, Itsuro Yamamoto, Mikihiko Ikezawa
    1986 Volume 55 Issue 8 Pages 2716-2722
    Published: August 15, 1986
    Released on J-STAGE: May 29, 2007
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    We have observed the surface enhanced Raman scattering on the CO molecules adsorbed on the silver films which were prepared in the ultra high vacuum at 15 K. The molecules chemically adsorb below 120 K. Three intense Raman bands were found to grow at 155, 180 and 2142 cm−1. With increasing the thickness of the CO overlayer on the silver surface, the peak of the stretching band at 2142 cm−1 shifts to the low energy side, and the intensity and the band width increase. This result clarifies large discrepancies among reported values of the peak and the band width by other researchers. Rare gas atoms of Kr and Xe overlaid on the CO molecules have been found to induce similar coverage dependence to that observed in the case of the CO overlayer. Therefore, the dipole-dipole interaction is not a main cause of the coverage dependence. Chemical effect is considered to be a possible cause.
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  • Junjiro Kanamori
    1986 Volume 55 Issue 8 Pages 2723-2734
    Published: August 15, 1986
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    The interrelation among the (7×7), (5×5) and c(2×8) reconstructions of the (111) surface of Si, Ge and related systems is discussed by extending previous analysis of the lattice gas model on a triangular net to a multi-layer model to the purpose of analyzing the DAS structure of the (7×7) restruction of Si (111) surface proposed by Takayanagi et al. It is concluded that the stacking fault characterizing the DAS structure has a good reason to appear and that it can solve the difficulties encountered in the previous analysis concerning the stability of the (7×7) state and also that of the c(2×8) state of Ge(111) whose DAS like atomic configuration is newly proposed. The atomic configuration of the (1×1) disordered state at high temperatures is discussed also. The possibility of the floating phase discussed previously is reexamined thereby.
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  • Naoto Nagaosa, Jun-ichi Takimoto
    1986 Volume 55 Issue 8 Pages 2735-2744
    Published: August 15, 1986
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    The one dimensional modified Hubbard model, which is a simplest model showing the neutral-ionic (NI) transition, is investigated by the quantum Monte Carlo simulation. The physical quantities concerning the ground state (the kinetic energy, the degree of charge transfer, the probability of the double occupancy), correlation functions and excitation energies (charge transfer gap ECT and magnetic gap EMAG) are calculated as functions of the site energy difference Δ. It is concluded that the model shows two phases according to Δ. The ionic phase (Δ<Δc) is characterized by the gapless spin wave which leads to the divergence of the correlation functions in the same manner as the case of Δ=0 (the Hubbard model). When Δ exceeds Δc, EMAG starts to rise continuously (neutral phase), while ECT has a minimum around Δc. Within the statistical accuracy, our simulation does not exclude the appearance of the metallic state at the transition point.
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  • Naoto Nagaosa, Jun-ichi Takimoto
    1986 Volume 55 Issue 8 Pages 2745-2753
    Published: August 15, 1986
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    The effects of the Coulomb interaction V (Madelung energy) between nearest neighbor sites on the neutral-ionic (NI) transition are studied. The transition becomes discontinuous due to this collective interaction. The degree of charge transfer ρ, charge transfer gap ECT, magnetic gap EMAG and imaginary-time current-current correlation function (which is related to the charge transfer absorption spectrum) are calculated by the quantum Monte Carlo simulation. From these results, we propose a new kind of elementary excitation—neutral-ionic domain wall (NIDW)—discussing the breakdown of the conventional exciton picture near the transition point.
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  • Naoto Nagaosa
    1986 Volume 55 Issue 8 Pages 2754-2764
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The effects of the electron-lattice interaction on the neutral-ionic (NI) transition are investigated. First, the degree of the dimerization u and of charge transfer ρ in the ground state are calculated at different values of S (the strength of the electron-lattice interaction). Next, we study the excited states of lattice-relaxed and Franck-Condon types. The neutral-ionic domain wall (NIDW) as well as the soliton structures are the examples of the former. By these considerations we classify the NI transition into three types. By analyzing the value of ρ, we determine the appropriate value of S for TTF-Chloranil, and discuss the optical, magnetic and electrical properties by these excited states.
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  • Hiroyuki Shiba
    1986 Volume 55 Issue 8 Pages 2765-2776
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    A strongly correlated Fermi liquid is realized in the valence fluctuation or dense Kondo system at low temperatures. In this work a variational Monte-Carlo method is applied to study the ground-state properties of the strongly correlated Fermi liquid with special emphasis on the magnetic and charge correlations. It reveals significant intersite magnetic correlations, while charge correlations are suppressed considerably.
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  • Mitsuru Suzuki, Hiroshi Bando, Takashi Takayama
    1986 Volume 55 Issue 8 Pages 2777-2782
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Transverse magnetoresistance in bismuth single crystals doped with 0.021 to 2.12 atomic % antimony has been measured in high magnetic fields up to 13 Tesla at low temperatures down to 0.5 K. Enhanced Shubnikov-de Haas oscillation has been observed within the doping level of 0.021 to 0.38 atomic % of antimony. Measured magnetoresistivity was converted into magnetoconductivity, which was compared with our previously obtained magnetoconductivity in ionized impurity doped bismuth. As a result the magnetoconductivity caused by neutral impurity scattering proved to be several orders of magnitude smaller than the case of ionized impurity scattering.
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  • Kosaku Yamada
    1986 Volume 55 Issue 8 Pages 2783-2789
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Diffusion coefficient of heavy particles in metals is calculated based on Kubo formula, by taking into account the interaction with conduction electrons. By a careful treatment of the thermodynamic limit we obtain the same expression for the coefficient as that derived by Kagan-Klinger method. Through the derivation we can see that though interaction between heavy particles and conduction electrons seems to be enhanced by a vertex renormalization, this enhancement is canceled by the wave-function renormalization. Thus, only the velocity of heavy particles is renormalized by a screening effect.
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  • Susumu Matsuo, Tsutomu Ishimasa, Yasushige Fukano
    1986 Volume 55 Issue 8 Pages 2790-2797
    Published: August 15, 1986
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    The superconducting transition temperature (Tc) of the fine particles of V–Si alloys with A-15 structure is studied. The average diameters range from 40 to 8000 Å. The Tc of the particles with the stoichiometric composition smaller than 170 Å is about 6∼7 K, which is less than half of that of the bulk material. The Tc of the particles with 22.0 and 20.0 at%Si is below 2.0 K, and increases to about 3 K after the annealing at 780°C for 4 hours. The large reduction in Tc is interpreted in terms of the broadening of the peak in the electronic density of states caused by the break-down of the translational symmetry in the particles.
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  • Kazunari Ohshima, Tetsuo Fujita
    1986 Volume 55 Issue 8 Pages 2798-2802
    Published: August 15, 1986
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    In layers of Ga fine particles prepared by gas evaporation technique, the temperature dependence of dc electric resistance was measured for average diameters of 22–56 nm. The resistance versus temperature curve of a layer has two superconducting transition points near 6 K and less than 2 K. The resistance of the layer decreases first at slightly higher temperature than the bulk transition of β phase Ga and the value of resistance does not fall to zero. The second sharp transition to zero resistance occurs at higher temperature than that of α phase bulk Ga. These results suggest an enhancement of the transition temperature Tc in α and β phase Ga fine particles. The observed values of Tc for α and β phase fine particles increase with decreasing average diameter of α phase particles in the layer. The enhanced Tc can be explained by change in phonon spectrum due to the surface of fine particle.
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  • Yoshikazu Suzumura
    1986 Volume 55 Issue 8 Pages 2803-2810
    Published: August 15, 1986
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    Effect of impurity pinning on quasi-one-dimensional superconducting systems is studied by extending a single impurity problem treated in the previous work [J. Phys. Jpn. 53 (1984) 1206] to the case of many impurities. The ground state energy and related properties are calculated numerically based on the self-consistent harmonic approximation. It is shown that a domain of the pinned state followed by the soliton-formation of the Josephson phase can exist in the spatially uniform superconducting state.
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  • Shinji Muramatsu, Norio Akiyama, Yuzo Mori, Hiroshi Ohkura
    1986 Volume 55 Issue 8 Pages 2811-2822
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The spin-mixing parameter ε is the probability that a spin is flipped into the opposite spin level in the optical processes in the presence of a magnetic field. In the Franck-Condon state, the mean and anisotropic parameters ε0 and δε have been calculated as a function of pumping photon energy Eph, on a theoretical framework in which the spin-orbit and electron-lattice interactions with Γ1+-, Γ3+-, and Γ5+-modes are included. The effect of the Γ5+-mode is predominant. By using ε0 and δε calculated, and introducing a mixing parameter εr1 in the non-radiative relaxation process, the experimentally-determined Eph-dependence of the net spin-mixing parameter εt and that of δε(1−2εr1) have been explained consistently. The εph-dependence of fractional dichroic differential pumping rate has been calculated.
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  • Toshio Itami, Takayuki Sato, Mitsuo Shimoji
    1986 Volume 55 Issue 8 Pages 2823-2829
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    The molar magnetic susceptibility χM of liquid Hg–Tl and Hg–Cs alloys was measured from room temperature to 748 K using the Fraday method. The observed χM of liquid Hg–Tl alloys shows positive deviations from the linear concentration dependence. For liquid Hg–Cs alloys a positively enhanced tendency of χM is found around 40 at.%Cs, though deviations from the linear law remain to be negative as a whole (“W shape”). Such a concentration dependence of χM is discussed in terms of the nearly free electron model. Positive deviations or positively enhanced tendencies (“W shape”) of χM in these liquid Hg alloys seem to be explained by taking into account electron-ion interactions. The temperature coefficient of χM, or dχM⁄dT, is discussed from the point of view of higher order ion-ion correlation effects recently found for some liquid mercury alloys.
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  • Chiaki Uyeda, Muneyuki Date
    1986 Volume 55 Issue 8 Pages 2830-2833
    Published: August 15, 1986
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    The high field magnetization of a polycrystalline orthorhombic antiferromagnet is calculated by changing the ratio of the orthorhombic anisotropy energies K2K1. It turned out that the peak of dM⁄dH curve always appear at the spin flop critical field Hc, independent of the ratio of K2K1. The calculated dM⁄dH curves coincide well with various experimental data.
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  • Hiroshi Maruyama
    1986 Volume 55 Issue 8 Pages 2834-2845
    Published: August 15, 1986
    Released on J-STAGE: June 01, 2007
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    Magnetization measurements were carried out on ordered and disordered Fe–Pt Invar alloys under high magnetic fields up to 18 T. Several anomalies were observed in the temperature variations of magnetization and high-field susceptibility χHF in the concentration range where the structure is believed to be completely γ phase. In the ordered alloys, an anomalous reduction in χHF appears below the inflection temperature Ti as estimated to be 80±5 K for 26.0 at% Pt–Fe. The magnetization changes anomalously also at the same temperature. In the disordered alloys, the reduced magnetization MsM0 decreases more gradually against reduced temperature TTc with increasing Fe content, while in the ordered alloys it decreases more quickly with increasing Fe content in the same manner as in Fe–Ni Invar alloys. These anomalies might be ascribed to the premartensitic transformation.
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