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Hideo Fusaoka
1989 Volume 58 Issue 2 Pages
339-341
Published: February 15, 1989
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We consider a new 1+1d, 2+1d and 3+1d sine-Gordon-type equation which differs slightly from the integrable 1+1d sine-Gordon equation. We have found exact solitary wave solutions to the new equation.
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Kiyoshi Sogo
1989 Volume 58 Issue 2 Pages
342-345
Published: February 15, 1989
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By use of the level
N representation of simply laced (
A,
D and
E) Kac Moody algebras, we construct their
Z algebra and W algebra explicitly, which provide novel extensions of the minimal series. In due course, the duality between rank and level is observed. Conformal charges for such models are given along with partition functions, supersymmetric extensions and corresponding Temperley-Lieb algebras.
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Yutaka Toyozawa
1989 Volume 58 Issue 2 Pages
346-347
Published: February 15, 1989
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The nonlocality of quantum mechanics, of which the paradoxical aspect was first pointed out by Einstein, Podolsky and Rosen and the experimental confirmation was recently done, is analysed to clarify its origin in the context of well established parallelism between classical statistical mechanics and quantum mechanics. In the former exist hidden variables, such as the impact parameter of inter-particle scattering, which governed the past interaction thereby causing the correlated state of now distant particles. The hidden variables must disappear in quantum mechanics where either the coordinate or its conjugate momentum drops out of the independent variables, being uncontrollable due to the uncertainty principle.
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Takeshi Kawabe
1989 Volume 58 Issue 2 Pages
348-351
Published: February 15, 1989
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The transverse and longitudinal spin-pair correlations are obtained as a function of temperature by the second-order Green’s function method. The longitudinal N. N. spin-pair correlation at the ground state becomes negative for anisotropy parameter η between the
XY model (η=0) and quite near the Heisenberg model (η∼1.0). It is predicted from these results that the first-order phase transition occurs near the Heisenberg limit. For η=0.9, it occurs at a temperature τ
c restricted by 2.4<τ<6.3.
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Yutaka Shimomura
1989 Volume 58 Issue 2 Pages
352-355
Published: February 15, 1989
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Based on the statistical theoretical results obtained in the previous work [J. Phys. Soc. Jpn.
55 (1986) 1904], a two-equation turbulence model in a rotating system is constructed. This model can explain experimentally observed asymmetric profiles of the mean streamwise velocity in a channel rotating about the spanwise direction.
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Shuji Ogata, Setsuo Ichimaru
1989 Volume 58 Issue 2 Pages
356-359
Published: February 15, 1989
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Through Monte Carlo (MC) simulation of a rapidly quenched one-component plasma, we elucidate microscopically how the local and extended bond-orientational symmetries develop in such a system and show in particular that layered structures with hexagonal symmetries emerge in an intermediate stage leading to a subsequent evolution into a bcc crystalline state. Dependence of the final states on the number of MC particles is examined.
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Holger Fehske, Dieter Ihle
1989 Volume 58 Issue 2 Pages
360-363
Published: February 15, 1989
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The effects of both the long- and shorter-wavelength spin fluctuations (SF), in particular of ferro- and antiferromagnetic SF, on the specific heat of exchange-enhanced paramagnetic metals are studied quantitatively within paramagnon theory on the basis of a uniaxially anisotropic band model. There are found different
T3 ln
T laws holding in different temperature ranges. The SF model considered is shown to provide a microscopic understanding of the localised-paramagnon picture.
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Hidetoshi Fukuyama, Hiroshi Matsukawa, Yasumasa Hasegawa
1989 Volume 58 Issue 2 Pages
364-367
Published: February 15, 1989
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The effective Hamiltonian for CuO
2 layer is derived based on Cu:
dx2−y2 and O:
pσ orbitals including the Coulomb interactions between Cu and O sites (
V) as well as the on-site Coulomb repulsion at Cu (
Ud) and O (
Up) sites. It is assumed that Cu
++ is stable under doping. We found a region where parameters permit an attractive interaction between two holes located in the neighboring sites of the same Cu atom resulting in the simultaneous enhancement of the antiferromagnetic exchange interaction between a Cu spin and a hole spin. The special case with vanishing
V and
Up, which is of interest in the context of RVB, is discussed without recourse to the classification of symmetric and nonbonding orbitals.
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Katsuichi Tankei, Akemi Sawada, Yosuke Nagaoka
1989 Volume 58 Issue 2 Pages
368-371
Published: February 15, 1989
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The conductance fluctuation of mesoscopic systems at zero temperature is studied numerically by using a simple model of random lattices, with emphasis on its behavior when the degree of randomness increases. It is found that the energy dependence of the conductance has a spiky structure near the insulating regime where the conductance completely vanishes. The result is explained qualitatively as a contribution from a small number of energy levels which remain extended.
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Arisato Kawabata
1989 Volume 58 Issue 2 Pages
372-375
Published: February 15, 1989
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Electron transport in a two-dimensional system with a constriction is investigated, and the criterion for the quantization of the conductance is discussed on the basis of the results of numerical calculations on a model. It is shown that the existence of a long quasi-one-dimensional channel with parallel boundaries is not the essential condition for the quantization.
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Kazuhiro Kuboki, Hidetoshi Fukuyama
1989 Volume 58 Issue 2 Pages
376-379
Published: February 15, 1989
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Effects of superconducting fluctuations on the relaxation rate of NMR are evaluated in the dirty limit for the
s-wave and
d-wave states. In the
s-wave state, there is a divergent contribution from the Maki process, but its magnitude is sensitive to the degree of three-dimensionality, whereas the contribution of the same process is vanishingly small in the
d-wave state.
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Kenji Fujiwara, Yoshio Kitaoka, Kunisuke Asayama, Hiroyuki Sasakura, S ...
1989 Volume 58 Issue 2 Pages
380-382
Published: February 15, 1989
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Nuclear quadrupole resonance (NQR) signals of Cu have been discovered in the high-
Tc superconducting oxide Bi–Pb–Sr–Ca–Cu–O with
Tc=109 K. It has been observed that there are two Cu sites with a different quadrupole coupling. The temperature dependence of the nuclear relaxation rate, 1⁄
T1, was similar to that of the CuO
2 plane in YBa
2Cu
3O
7. It is found that the 1⁄
T1 for the Cu site demonstrates the reflection of the strong Cu-d spin correlation.
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Nobuaki Miyakawa, Daisuke Shimada, Tadaharu Kido, Nobuo Tsuda
1989 Volume 58 Issue 2 Pages
383-386
Published: February 15, 1989
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A fine structure was observed above the gap voltage in the tunneling conductance of a Bi
2Sr
2CaCu
2O
8-GaAs junction at 4.2 K. It is due to electron-phonon interaction, suggesting that this superconductivity is essentially due to phonons.
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Daisuke Shimada, Nobuaki Miyakawa, Tadaharu Kido, Nobuo Tsuda
1989 Volume 58 Issue 2 Pages
387-389
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A multiphonon exchange model is proposed to explain the high critical temperature and its increase with the number of CuO
2 layers between Bi(Tl)
2O
2 layers in copper oxides. In this model, the Cooper pair is formed through the exchange of multiphonons on different CuO
2 layers.
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Yoshitami Ajiro, Hikomitsu Kikuchi, Takushi Okita, Meiro Chiba, Kimio ...
1989 Volume 58 Issue 2 Pages
390-393
Published: February 15, 1989
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Nuclear spin-lattice relaxation of
133Cs has been studied in the frustrated antiferromagnet, CsCoCl
3. A pronounced anomaly in the relaxation rate was observed at the lower transition temperature,
TN2=10 K, whereas a weak change in the relaxation rate was observed at the upper transition temperature,
TN1=21 K. The results are discussed in terms of the characteristic dynamics of domain wall solitons which propagate in disordered magnetic chains which feel no molecular field from the neighboring chains.
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Toru Shigeoka, Hironobu Fujii, Kenji Yonenobu, Kiyohiro Sugiyama, Mune ...
1989 Volume 58 Issue 2 Pages
394-397
Published: February 15, 1989
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Magnetic properties of PrCo
2Si
2 single crystals have been studied by measurements of high-field magnetization, magnetic susceptibility and electrical resistivity. Anomalous behaviors in the resistivity appear at three successive magnetic phase transition temperatures of 9, 17 and 30K. The magnetic susceptibility is highly anisotropic and is analyzed using the single-ion Hamiltonian, including the crystal-field and molecular-field effects. The thermal variations of the susceptibilities can be well reproduced by the crystal-field parameters estimated from the point-charge model. Metamagnetic transitions with four steps are observable in the
c-axis magnetization process up to 300 kOe. The magnetization process is discussed in terms of the incommensurate exchange field model in the Ising system proposed by Date.
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Yukikuni Akishige, Yishiro Yoneya, Kikuo Ohi, Etsuro Sawaguchi
1989 Volume 58 Issue 2 Pages
398-401
Published: February 15, 1989
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Dispersion of the refractive indices and temperature dependence of the birefringence have been examined in layered perovskite-type Sr
2Nb
2O
7. The refractive indices
na,
nb and
nc at λ=0.633 μm are 2.16(2), 2.05(2) and 2.15(2), respectively, at 22°C. The dispersions of the refractive indices have been analyzed using a single-term Sellmeier oscillator model. The birefringence
na−
nc vs
T curve exhibits an anomaly around the incommensurate transition at
Ti=216°C. When the sample is annealed at a temperature just below
Ti, the sample exhibits a “memory effect” on the birefringence curve. The effect is explained by the presence of mobile defects interacting with the incommensurate modulation.
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Shin Imada, Takeo Jo
1989 Volume 58 Issue 2 Pages
402-405
Published: February 15, 1989
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Effects of the hybridization between the 4
f and valence band states on the multiplet structures in La 3
d and 4
d core X-ray photoemission spectra (XPS) are discussed for LaF
3, LaCl
3, and La
2O
3 on the basis of the Anderson model considering the multiplets arising from the interaction between a 4
f electron and a core hole described by the Slater integrals. An interpretation for the apparent success of the previous analyses of the 3
d-XPS excluding the multiplet effect is given, and the necessity of including it in the analyses of the 4
d-XPS is discussed.
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A. Roy Chowdhury, R. S. Banerjee
1989 Volume 58 Issue 2 Pages
407-411
Published: February 15, 1989
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We have analysed the complete integrability of a new nonlinear system in three dimension recently suggested by Melnikov. On the one hand we have adopted the technique of singular point analysis for ascertaining the above property and on the other we have used the methodology of Hirota for construction of multi-soliton solutions explicitly. It is observed that this equation conforms to the Cauchy-Kawalevskya criterion and can be said to be completely integrable.
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Akira Nakamura
1989 Volume 58 Issue 2 Pages
412-422
Published: February 15, 1989
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We consider the new derivations of the bilinear
N-soliton solutions for the KP (two dimensional KdV) equation which utilize the Jacobi formula of the matrix algebra. The periodic waves of explode-decay type are shown to be derived easily in the present approach. It is shown that physically important several other nonlinear equations can be cast into our present form of “four-operators” bilinear equation.
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Nobuhiko Saitô, Takeshi Takeda, Yasushi Shimizu
1989 Volume 58 Issue 2 Pages
423-430
Published: February 15, 1989
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The nature of the bifurcation of the fixed points which become stable or unstable alternately on changing a parameter
p is studied phenomenologically by a two-dimensional area-preserving mapping. It is shown that the fixed point generally changes its character sequentially as elliptic, ordinary hyperbolic, elliptic, reflection hyperbolic, elliptic, ordinary hyperbolic, and so on, and the values of the parameter
pk when the stable fixed (elliptic) point changes to unstable fixed point (hyperbolic of either type) define a ratio δ=(
pk−
pk−1)⁄(
pk+1−
pk) which ternds for
k→∞ to either one of 1, ∞, or exp (π⁄
a) where
a is a constant depending on the system, as far as in examples examined here. Two hamiltonian systems which provide δ=exp (π⁄\sqrt2) and 1 are discussed in the light of the present formalism.
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Masakazu Ichiyanagi
1989 Volume 58 Issue 2 Pages
431-444
Published: February 15, 1989
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This is the second in a series of papers which intends to develop a statistical mechanical theory capable of independently treating responses to thermal as well as mechanical disturbances. The essential idea is to develop a method of solving the Liouvill-von Neumann equation for the density matrix of a many-body system in a time-dependent Gibbsian form. The theory is made determinate by defining the relative entropy, which will reflect the character of the entropy production in our model. In this paper, rigorous expressions are obtained for nonlinear responses, which contain all the most general consequences of statistical mechanics regarding the macroscopic variables. In particular, the Onsager reciprocity relations follow from the formula in nonlinear regions. An attempt to treat a stationary state where heat is produced is made in terms of a nonequilibrium density matrix satisfying the Liouville-von Neumann equation.
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Toshiaki Iitaka
1989 Volume 58 Issue 2 Pages
445-450
Published: February 15, 1989
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The self energy is obtained for an atom moving at a uniform velocity parallel to the surface of a semi-infinite metal. The van der Waals potential is shown to be velocity dependent. It is shown that the surf-riding resonance of atom and surface plasmon plays important role.
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Hideo Tsuru
1989 Volume 58 Issue 2 Pages
451-462
Published: February 15, 1989
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Line disclinations of uniaxial nematics are classified into two types: 2
nπ ones which are topologically removable and (2
n+1)π ones which are not. The equilibrium configurations of the director of 2π disclinations in cylindrical geometry are examined by nonlinear equations derived by Frank elastic theory. The equilibrium equations for splay-bend and bend-twist deformations are solved exactly. For the bend-twist cases, the effect of a magnetic field induced by the central current is examined. When the disclinations are non-singular, the solutions are described by hyperbolic and trigonometric function. In other cases they are in general expressed in terms of elliptic functions.
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Masaki Takashima, Kazuhiro Mori
1989 Volume 58 Issue 2 Pages
463-472
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This paper is concerned with the problem of the onset of buoyancy driven instability in a horizontal layer of binary fluid mixture which is heated internally by a uniform distribution of heat sources. The layer is bounded below by a thermal insulator and above by a rigid wall of constant temperature. Linear stability theory is applied to derive an eigenvalue system of eighth order which is then solved by the power series method. In order to reduce the amount of numerical work, Galerkin’s method is also used. For wide ranges of various parameters, the conditions under which instability sets in are determined in detail.
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Akihide Fujisawa, Shori Onodera, Kenro Miyamoto
1989 Volume 58 Issue 2 Pages
473-481
Published: February 15, 1989
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The growth rates of
m=1 ideal MHD instabilities in RFP configurations are calculated by the use of the Hain and Lüst equation in RFP configuration with finite pressure. Two kinds of
m=1 instabilities are studied in this paper; one is a current-driven internal mode whose plasma displacement is localized around the plasma center region, and the other is a pressure-driven external mode whose plasma displacement is localized on the plasma surface. The contours of the growth rate of both instabilities are present in a
Θ0−
Θ diagram (
q0=
a⁄
RΘ0), in which each point corresponds to a RFP configuration with a different current profile. This diagram shows that the growth rate of the internal mode is closely related to the degree of relaxation.
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Kimitaka Itoh, Sanae-I. Itoh, Atsushi Fukuyama
1989 Volume 58 Issue 2 Pages
482-488
Published: February 15, 1989
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Radial transport driven by rf heating in toroidal helical systems with the large helical ripple is studied. The cyclotron resonance heating changes the pitch angle of resonating particles, so that the transition from the transit orbit to the trapped one occurs. The deviation of the average minor radius of the particle orbit from the magnetic surface strongly depends on the pitch angle of the particle velocity. Owing to this dependence, the slight change in the pitch angle by heating can generate a large step in the radial location. The approximate forms of the driven radial flow, which is rf-power-dependent, and the deformation of the heating profile are obtained. It is found that the deposition profile in this configuration is hardly made sharper than a critical gradient length. The injection of the heating power from the inside of the torus is preferable to improve the heating efficiency and to overcome the density clamping.
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Yoshiomi Kondoh
1989 Volume 58 Issue 2 Pages
489-503
Published: February 15, 1989
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The sufficient condition for relaxed minimum-energy states is derived from the energy principle for a nonideal MHD plasma using two different processes of formulation. The Euler equation for the reminimization of the energy integral is derived and shown to yield the marginal stable perturbations for the sufficient condition. To determine the transition point of the relaxed mode, an extended stability limit for the β=0 relaxed states is derived from the sufficient condition, using the eigenvalue analysis for the Euler equation. The extended stability limit is solved in the 1st-order approximation to explain the deviation of the experimental stability limit from the idealized stability limit obtained by Taylor [J. B. Taylor, Rev. Mod. Phys.
58 (1986) 741]. The stability limit for the finite β relaxed states is also discussed.
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Hideo Kozima, Keiichiro Yamagiwa, Tsutomu Tanaka, Hiroyuki Matsubara, ...
1989 Volume 58 Issue 2 Pages
504-510
Published: February 15, 1989
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The propagation of an ion-acoustic soliton in an Ar (or Ar–He) plasma is investigated experimentally in a double plasma device. The various patterns of signals propagating from the separation grid into the target region are classified into three types. Besides the normal soliton pattern, there appear signals with either a shallow dip or a deep valley. The K-dV equation with a term expressing the effect of ion Landau damping is solved numerically with parameters corresponding to the experimental conditions. One of the types observed in the experiment (with a shallow dip) is fully reproduced theoretically with the corresponding plasma parameters. Effects of the initial height of the perturbation on the evolution of the signal are investigated experimentally and theoretically. The minority He ion which causes an increase of the ion Landau damping rate had the same effect as the decrease of the initial height of the signal.
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Hitoshi Kikuchi, Katsunori Saito, Hirokazu Gesso, Shoichi Shiina
1989 Volume 58 Issue 2 Pages
511-518
Published: February 15, 1989
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The superposition of a relatively weak
l=−1 torsatron field on a main
l=1 torsatron field leads to the improvement of the confinement properties due to the formation of a local magnetic well, which results from the local curvature of the helical magnetic axis with a larger excursion in the major radius direction. This
l±1 helical magnetic axis system has a comparatively simple, compact coil structure. Here the vacuum configuration properties of
l=±1 system are described.
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Shingo Ishiwata, Shinsuke Watanabe, Hiroshi Tanaca
1989 Volume 58 Issue 2 Pages
519-526
Published: February 15, 1989
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Self-modulation and self-focusing of ion wave in a two-electron-temperature plasma composed of cold and hot electrons and positive ion have been theoretically investigated based on the nonlinear Schrödinger equation describing the wave. For the ion wave of large wavenumber, the modulational instability occurs irrespective of temperature and density ratios of the hot electron to the cold electron. If the temperature ratio is larger than ∼10, the ion wave of any wavenumber turns out to be unstable modulationally at a critical density ratio. The self-focusing of ion wave, on the other hand, scarcely occurs. Between two critical densities, however, the ion wave of small wavenumber becomes unstable with respect to transverse modulation if the temperature ratio is superior to ∼10.
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Masatoshi Saito, Haruyuki Takahashi, Shigeru Tamaki
1989 Volume 58 Issue 2 Pages
527-532
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X-ray powder diffraction measurements of solid solution (Ag
xCu
1−x)Br were carried out from room temperature to 300°C. Anomalous changes in their integrated intensities were observed at about 230°C and at a certain value of
x. These changes were interpreted as a phase transition due to the disordering of cations between octahedral and tetrahedral sites. On the basis of a disorder model, the calculated structure factors were fitted to the observed ones by means of the least square method. It was concluded that the cations which occupy the tetrahedral sites suffer from strongly anisotropic and anharmonic vibrations.
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Yoshitaka Michihiro, Akira Kojima, Takashi Ohno, Tatsuo Kanashiro
1989 Volume 58 Issue 2 Pages
533-537
Published: February 15, 1989
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The ultrasonic attenuation of ionic conductors is studied in a model taking into account the mutual coupling between mobile ions in addition to the coupling between mobile ions and lattice ions. The result is compared with the experiments in a polycrystal β-Ag
3SI. The measurements are taken at 10, 30, 50 and 70 MHz for longitudinal waves from room temperature to the β-γ transition temperature employing a standard pulse echo technique. The activation energy and the attempt frequency are obtained for the hopping of mobile Ag
+ ions. The authors also estimate the magnitude of the interaction parameter of mutual coupling between mobile ions relative to that between lattice ions and mobile ions.
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Koh-ichi Takesawa, Shin’ichi Takeda, Sh\={u}zi Harada, Shigeru T ...
1989 Volume 58 Issue 2 Pages
538-543
Published: February 15, 1989
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The velocity of sound wave propagation and attenuation have been measured in molten AgX (X=Cl, Br and I) at temperatures beginning from the respective melting points to about 850°C. The observed sound velocities decrease almost linearly with increasing temperature, and sound attenuation in molten AgI is larger than that in molten AgBr and AgCl. The adiabatic compressibility is derived from the sound velocity; in these molten salts, the adiabatic compressibilities are discussed from the viewpoint of the mixed characteristics of covalent and ionic one. The isothermal compressibility of liquid AgI was calculated by using the three partial distribution functions which were already calculated by the hypernetted chain approximation using the pair potentials. The calculated result is comparable to the experimental one.
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Shin’ichi Takeda, Sh\={u}zi Harada, Shigeru Tamaki
1989 Volume 58 Issue 2 Pages
544-551
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Ultrasonic velocity and absorption measurements have been carried out for liquid In–Te alloy from the melting points to about 850°C. Observed sound velocities of alloys have the minimum values against temperature and the corresponding adiabatic compressibilities have the maximum values. The characteristic temperature dependence of the adiabatic compressibility in this system has been explained by the phase transition model. The observed sound attenuation in this system is also discussed in connection with the viscosity.
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Yukihiko Sasaki
1989 Volume 58 Issue 2 Pages
552-562
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Young’s moduli along [100], [010], [001], [011], [101], [110] by composite-bar resonator method and sound velocities of longitudinal and transverse waves along [100], [010], [001] by pulse echo method are measured in the ferroelectric crystal of (NH
4)
2BeF
4 over a range from −150°C to 150°C. All the elastic constants are obtained by a least square method. A method to obtain the elastic compliance constants
s23,
s13 and
s12 from six measurements (
s11,
s22,
s33,
c11,
c22,
c33) is also proposed. Anomalies in constants except
c55 are explained by a phenomenological theory including higher order terms. The anomaly in
c55 is, however, shown due to the coupling of a normal coordinate
Q(
B2g) at
Γ-point with a strain
S5 both belonging to
B2g.
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Hiraku Nishimori, Tomohiro Nukii
1989 Volume 58 Issue 2 Pages
563-570
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A numerical study of a quenched complex field with a rotationally symmetric (φ
4-type) local free energy is performed by use of a coupled map lattice model. We visualize the time evolution of a quenched system especially the dynamics of line defects, i.e. vortex lines. A power law about the evolution of the defect density is confirmed to hold. In the case of deep quench, it is found that at the late stage of the evolution process, many defect lines are formed and their total length
N decreases with time as
N∝
t−0.75±0.05 in a wide range of time. On the contrary, in the case of shallow quench, the evolution process is quite different from that of the former case, namely only few topological defects are formed and the system approaches to the final state much faster than it does in the former case.
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Masato Shinmi, Dale A. Huckaby
1989 Volume 58 Issue 2 Pages
571-576
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A lattice gas is studied in which the two enantiomeric forms of a molecule (
d and
l) are adsorbed onto a triangular lattice. The phase diagram is investigated using a Guggenheim-McGlashan approximation with two order parameters. For a range of intermolecular interactions, such as may occur between the zwitterion forms of an amino acid, the system is found to exhibit a tricritical point at which a
d-rich phase, an
l-rich phase, and a racemic phase simultaneously become a single phase.
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Shinichi Yano, Masahiko Sahara, Kozo Iwauchi
1989 Volume 58 Issue 2 Pages
577-583
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Dielectric properties of Ca
2Sr(CH
3CH
2COO)
6 (DSP), Ca
2Sr(CH
3CH
2COO)
6(1−x) (HCF
2CF
2COO)
6x(HCF
2CF
2-DSP) and Ca
2Sr(CH
3CH
2COO)
6(1−x)(HCF
2COO)
6x(HCF
2-DSP) crystals have been studied in the temperature range from 4 K to room temperature at several frequencies between 1 and 100 kHz. The DSP crystal underwent I–II, II–III and III–IV phase transitions near 281.2, 76 and 58 K, respectively. In HCF
2CF
2-DSP and HCF
2-DSP crystals, the phase transition temperature decreased for the I–II phase transition and increased for the II–III phase transition with the increase in the content of HCF
2CF
2COO/HCF
2COO ion (
x). These results were qualitatively explained by the motion of propionate group associated with the phase transitions.
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Hikaru Kawamura
1989 Volume 58 Issue 2 Pages
584-596
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Phase transition of the antiferromagnetic plane rotator (
XY) model on the (
d=3)-dimensional layered-triangular lattice is studied by means of Monte Carlo simulations. A single continuous transition is observed with the novel critical exponents α=0.40±0.10, β=0.25±0.02, γ=1.10±0.10 and ν=0.53±0.03. The chirality is found to order simultaneously with the spins, the associated chirality exponents being β
κ=0.40±0.04 and γ
κ=0.80±0.08. These exponents satisfy the scaling relations ν
κ=ν and α+2β
κ+γ
κ=2, and the associated crossover exponent, φ
κ=β
κ+γ
κ\simeq1.2, exceeds the susceptibility exponent γ. Previous Monte Carlo data for the corresponding (
n=3) Heisenberg model are also reanalyzed taking account of the spin-wave correction, to yield the revised estimates of exponents α=0.34±0.10, β=0.28±0.02, γ=1.10±0.10 and ν=0.55±0.03. The Monte Carlo results support the renormalization-group prediction that the critical behavior of these layered-triangular antiferromagnets is governed by a new type of chiral fixed point.
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Shigeo Imaizuni, Carl W. Garland
1989 Volume 58 Issue 2 Pages
597-601
Published: February 15, 1989
Released on J-STAGE: May 29, 2007
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We have carried out a study of the ordering of cesium perfluoro-octanoate (CsPFO) micelles in water using high-resolution ac calorimetric techniques and differential scanning calorimetry (DSC). Aqueous solutions of CsPFO undergo two order-disorder phase transitions: a second-order nematic-smectic A (or lamellar) transition and a very weakly first-order nematic-isotropic transition. Small excess heat capacity peaks associated with each of these transitions have been observed for solutions that are 41 wt% CsPFO and 65 wt% CsPFO. The integrated transition enthalpy ∫
ΔCpd
T for the N-SmA transition is about 0.14 J g
−1 (Joule per gram of CsPFO solute) at 65 wt% and about 0.10 J g
−1 at 41 wt%. No qualitative difference was observed in the character of these
ΔCp(N-SmA) peaks in spite of a reported change in the transition from second order at 41 wt% to tricritical near 65 wt%. The integrated transition enthalpy was larger for the N-I transition: about 0.23 J g
−1 at 65 wt% and about 0.27 J g
−1 at 41 wt%.
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Kaoru Iwano, Yasushi Wada
1989 Volume 58 Issue 2 Pages
602-609
Published: February 15, 1989
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Eilenberger equations are derived for trans-polyacetylene with random impurities. The Takayama-Lin-Liu-Maki model is generalized to include the impurity effect. Two types of disorders, namely, site-type and bond-type are studied. Since the original derivation, for dirty superconductors, does not work for the Peierls system, new derivation is given with the help of self-consistent argument. The equations are solved, using the assumption that dimerization pattern is uniform. It turns out there are no differences between the two types of disorders and we get exactly the same results as for the gapless superconductors with paramagnetic impurities. Electronic density of states and order parameter are calculated as functions of disorder parameter. They are compared with the results by Xu and Trullinger, obtained by supersymmetry arguments. Present method gives an overall agreement as far as the density of states is concerned. There is a difference in the order parameter.
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Noriyuki Kurita, Kenji Nakao
1989 Volume 58 Issue 2 Pages
610-621
Published: February 15, 1989
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The band structures of manganese chalcogeno-phosphate MnPS
3 and iron chalcogeno-phosphate FePS
3 are calculated self-consistently. From the calculation of the total energies of two types of magnetic structures of MnPS
3, the experimentally observed magnetic structure is proved more stable. Furthermore, by comparing the band structures of MPS
3 family (M=Mn, Fe, Ni, Zn), it is found that FePS
3 and NiPS
3 are more active to the Li intercalation than ZnPS
3 and MnPS
3, and that NiPS
3 is the best cathode material in secondary lithium batteries in the MPS
3 family.
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Xu-guang Zheng, Hisao Kuriyaki, Kazuyoshi Hirakawa
1989 Volume 58 Issue 2 Pages
622-626
Published: February 15, 1989
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The electrical resistivity and the Hall coefficient of the layered compound ZrSe
2 and HfSe
2 grown by iodine vapour transport method have been measured. High anisotropy in electrical resistivities has been found for these compounds. The Hall mobility exhibits a temperature dependence of the form μ∝
T−1.6 in ZrSe
2 as well as in HfSe
2. It is well explained in terms of homo-polar-mode optical scattering.
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Takashi Uchino, Kôki Takita, Kohzoh Masuda
1989 Volume 58 Issue 2 Pages
627-638
Published: February 15, 1989
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A systematic study of a new type of magnetophonon effect associated with a recombination process with emission of two TA phonons is carried out on Hg
1−xMn
xTe for
x=0.25∼1.0% and HgTe, using high-quality LPE crystals. Magnetophonon resonance recombination extrema are observed in the longitudinal magnetoresistance, which shows dependences on Mn composition, the temperature and the magnetic field direction relative to the crystallographic orientation. Spin-flip transition peaks are well resolved and the exchange parameter β is determined as 0.62 eV. In the samples with
x=0.5%, impurity transitions are detected and an impurity level is deduced at (2.0±0.2) meV above the top of the valence band in a magnetic field. It is demonstrated that this new type of magnetophonon effect is a powerful tool for study of the band structure near the band edge in zero-gap semiconductors.
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Akemi Sawada, Katsuichi Tankei, Yosuke Nagaoka
1989 Volume 58 Issue 2 Pages
639-645
Published: February 15, 1989
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In order to study the Aharonov-Bohm(AB) effect observed in metal rings attached with leads, we adopt the tight-binding model and numerically calculate the conductance by making use of the Landauer formula and the transfer matrix method. It is confirmed that the magnitude of the conductance fluctuations is almost independent of the system size, consistent with the universal conductance fluctuations. We also find that, while the amplitude of the AB oscillation of the conductance is reduced when the ring length increases, it is enhanced when the lead length increases.
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Yoshiko Oi Nakamura, Kazumitsu Tagawa
1989 Volume 58 Issue 2 Pages
646-657
Published: February 15, 1989
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The dielectric function ε(
q, ω), for arbitrary wave vector
q and frequency ω, is calculated in the random phase approximation (RPA), for the cases of (i) a single layer and (ii) a pair of layers of two-dimensional electron gas where the electrons in the different layers are interacting with by the coulomb force but no electronic transfer does occur between the different layers. Closed expressions for the plasmon dispersion relation are derived for both cases. For the single layer case, it is shown that the widely believed \sqrt
q type plasmon dispersion relation stands for only in a very narrow region near
q=0 which becomes narrower as the carrier density increases. For the case of a pair of layers, two plasmon branches are obtained; in the long wavelength limit, one has a \sqrt
q type dispersion relation and the other has a linear dispersion relation in
q, that is, an acoustic plasmon. The calculations are extended to the system of
N layers and the condition for the appearance of an acoustic plasmon branch is discussed.
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Shoichi Mase, Takashi Yasuda
1989 Volume 58 Issue 2 Pages
658-667
Published: February 15, 1989
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By making use of an algebraic method in classifying the normal modes, we calculated phonon dispersion curves and density of states curves of the high
Tc superconductors, Bi
2Sr
2CaCu
2O
10−x, and Bi
2Sr
2Ca
2Cu
3O
12−y. Here, the crystal structures are approximated by tetragonal ones with one formula unit, instead of an orthorhombic one with 5 formula units proposed by Kajitani
et al. The force constants between atoms are estimated from the results in our previous paper. Similarly to that of YBa
2Cu
3O
7, the density of states curve splits into, roughly speaking, two parts in both Bi
2Sr
2CaCu
2O
10−x and Bi
2Sr
2Ca
2Cu
3O
12−y, the higher energy part being mainly contributed from Cu–O, O–O, Ca–O and Sr–O bonds. The role of phonons in high
Tc superconductivity is briefly discussed in relation with YBa
2Cu
3O
7.
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Kenji Takanaka
1989 Volume 58 Issue 2 Pages
668-672
Published: February 15, 1989
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We consider the angular derivatives d
Hc2(θ)⁄dθ and d
Hc3(θ)⁄dθ at θ=0, where
Hc2(θ) and
Hc3(θ) are the upper critical field and the sheath critical field, and θ is the angle to denote the magnetic field direction measured from the maximum critical field. It is found that the angular dependence of the critical fields exhibits a cusp if the nucleation of the order parameter takes place at the definite position of the sample.
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J\={u}ichiro Arai, Hajime Shimizu, Masaru Mita
1989 Volume 58 Issue 2 Pages
673-678
Published: February 15, 1989
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Superconductivity and magnetic properties of YBa
2(Cu
1−xFe
x)
3O
7−y with
x=0−0.1 are investigated by the measurements of static magnetic susceptibility, electrical resistance, weight change and lattice parameters. Substitution of Fe atoms for Cu atoms causes orthorhombic to tetragonal phase transition at about
x=0.035 and depresses critical temperature
Tc from 95 K to 32 K at
x=0.1. The effective magnetic moment per Fe, about 5.5 μ
B below
x=0.01 decreases to 3.6 μ
B at
x=0.1. The removal of oxygen atoms in the specimens of superconducting tetragonal phase with
x=0.04 by quenching brings about remarkable expansion of
c-axis and decreases
Tc from 74 K to below 4.2 K. The effective moment per Fe was found to decrease from 4.4 μ
B to 3.3 μ
B with increase of oxygen deficiency due to quenching. Causes of reduced iron effective moments due to increase of iron concentration and oxygen deficiency are discussed in consideration of superexchange interaction between Fe and Cu spins.
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