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Mitsuaki Ginoza
1985 Volume 54 Issue 8 Pages
2783-2785
Published: August 15, 1985
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The Blum’s solution for a primitive model of electrolytic solutions has been generalized to the one for a charged hard sphere system with screened Coulombic interactions.
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Mitsugu Matsushita, Keiz\={o} Sumida, Yasuji Sawada
1985 Volume 54 Issue 8 Pages
2786-2789
Published: August 15, 1985
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Static and dynamic light scattering measurements are performed on colloidal aggregates of polystyrene uniform latex particles. The light scattering structure factor
S(
k) is found to exhibit characteristic power-law decay on
k which means that the internal structure of the aggregating clusters is self-similar. The dependence of the mean cluster size on time is also found to show scaling behavior. The fractal dimension and dynamic scaling exponent of the aggregating clusters are determined.
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Masahiro Wakatani, Yuji Nakamura
1985 Volume 54 Issue 8 Pages
2790-2792
Published: August 15, 1985
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Neoclassical plateau diffusion coefficient in a toroidal helical system is calculated by using the magnetic coordinates. It is assumed that dominant contribution to the plateau regime comes from particles moving along the trough of the helical ripple with parallel velocity almost independent of the toroidal coordinate. It is shown that an elliptic deformation due to
l=2 helical coils enhances the diffusion which is opposite to that in vertically elongated tokamaks.
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Seiichi Miyajima, Takehiko Chiba
1985 Volume 54 Issue 8 Pages
2793-2796
Published: August 15, 1985
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Differential thermal analysis experiments are carried out on two reentrant liquid crystals, CBOBP and OBBC, whose phase sequences are Crystal–S
A1–RN–S
Ad–N–I and Crystal–RN–S
Ad–N–I, respectively. The reentrant phase transition (RN/S
Ad) is accompanied by a significantly smaller thermal anomaly than the ordinary ones (S
A1/RN and S
Ad/N). S
A1/RN had a larger thermal anomaly than S
Ad/N. Comparatively strong temperature-dependence of the heat capacity is suggested in RN. All these findings support the picture of competing incommensurate smectic periodicities and the phenomenological optimum density theory.
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Hideo Onuki, Terubumi Saito
1985 Volume 54 Issue 8 Pages
2797-2799
Published: August 15, 1985
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By use of synchrotron radiation of 40≤
hν≤110 eV, angle-resolved photoemission spectroscopy (ARPES) is applied to NaCl single-crystals to investigate the electronic structure of the valence band. It is recognized that the results obtained can be well understood by the direct-transition model, and the ARPES is found very useful in determination of the energy vs momentum dispersion relation. The valence band dispersion of NaCl is determined along the
Δ-direction (
Γ−
X).
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Masaaki Yamaguchi, Nobuhiko Nishida, Kazuo Morigaki, Hidehiko Ishimoto
1985 Volume 54 Issue 8 Pages
2800-2803
Published: August 15, 1985
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Superconductivity was observed for the first time for Ge
1−xAu
x films prepared by rf sputtering at room temperature. The films are composed of the diamond structure (Ge)-and hexagonal close packing (Ge–Au)-crystalline phases. The origin of superconductivity is discussed in the light of recent observations of superconductivity for multi-layered films and very thin-Ag films on Ge clean surfaces.
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Yoshichika \={O}nuki, Kazuyuki Shibutani, Toshiyuki Hirai, Takemi Koma ...
1985 Volume 54 Issue 8 Pages
2804-2807
Published: August 15, 1985
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Impurity effects of the starting material Ce and the crucible on the Kondo lattice formation of CeCu
6 have been studied through the measurements of the electrical resistivity, thermoelectric power, negative magnetoresistance and magnetic susceptibility.
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Minoru Takahashi, Miki Yamada
1985 Volume 54 Issue 8 Pages
2808-2811
Published: August 15, 1985
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Using Bethe ansatz integral equations, we calculate the free energy and susceptibility of spin-1/2 one-dimensional Heisenberg ferromagnet (
Remark: Graphics omitted.), (
J<0) at
T≥0.004|
J|. We find that the free energy and susceptibility are expanded by \sqrt
T⁄|
J| at low temperature:
(
Remark: Graphics omitted.)
The first term of free energy coincides with the spin wave calculation. The first term of susceptibility coincides with Fisher’s solution of classical Heisenberg Ferromagnet. We conclude α=−0.5 and γ=2.
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Hiroyasu Shimizu, Fujiya Ikuta
1985 Volume 54 Issue 8 Pages
2812-2815
Published: August 15, 1985
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The Raman spectra of crystalline deuterated formic acid (DCOOD) in a diamond anvil cell have been measured at pressures up to 100 kbar and 300 K. The frequency of the stretching O–D mode near 2000 cm
−1 decreases strongly with increasing pressure, which is due to the increasing strength of the deuterium bonds in the zig-zag chain. The pressure-induced phase transition at about 45 kbar has been found on the characteristic high-pressure behavior of the stretching O–D, the stretching C=O, and the bending C–D modes, which is discussed by focusing on the
cis-trans conformational change associated with the deuteron transfer.
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Kenji Ohkuma
1985 Volume 54 Issue 8 Pages
2817-2828
Published: August 15, 1985
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The thermodynamics for the quantum three wave interaction model is studied in the Fermion Case I. It is found that the Bethe Ansatz method by Yang and Yang is applicable to this model. The integral equations for the thermal equilibrium and excited states are derived.
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Morio Miyagaki, Toshio Hara, Chiaki Yokoyama, Tatsuo Nakayama, Hiroshi ...
1985 Volume 54 Issue 8 Pages
2829-2833
Published: August 15, 1985
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Interaction mean free paths of projectile fragments emitted from relativistic Fe–C and Fe–Pb interactions were measured by means of emulsion stacks arranged at just downstream (S-stacks) and at 15 cm downstream of targets (L-stacks). There is no difference in mean free paths of fragments emitted from both target interactions, and in S- and L-stacks. The difference of mean free paths between upstream and downstream parts of stacks is also undetected by two analysing methods. The ‘Anomalon effect’ is not observed in present experiment.
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Akira Yoshizawa, Kiyosi Horiuti
1985 Volume 54 Issue 8 Pages
2834-2839
Published: August 15, 1985
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A subgrid-scale (SGS) kinetic energy model for the large-eddy simulation (LES) of turbulent flows is constructed with the aid of the statistical results obtained from the two-scale direct-interaction approximation. In this model, the SGS Reynolds stress is written in terms of a generalized SGS eddy-viscosity representation which is expressed by using the SGS kinetic energy and the characteristic grid width. A model equation for the SGS kinetic energy is combined with the grid-scale Navier-Stokes and continuity equations to lead to an LES model of one-equation type. The usual Smagorinsky model is derived as its special case, and critical comparison is made between them.
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Shigeo Kida
1985 Volume 54 Issue 8 Pages
2840-2854
Published: August 15, 1985
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A two-dimensional high-Reynolds number flow is simulated starting from a high-symmetric random initial condition. At early stages of evolution narrow band regions of vorticity are built-up by stretching of equivorticity lines. They are broken down into a block of eddies of very complicated structure through a rolling-up instability and subsequent stretching and reconnection processes of equi-vorticity lines. Around this break-down time the enstrophy-dissipation rate takes the maximum value and the power form of the energy spectrum in the inertial range changes from
k−4.2 to
k−3.
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Kiyosi Horiuti
1985 Volume 54 Issue 8 Pages
2855-2865
Published: August 15, 1985
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Turbulent flow in a straight rectangular channel is numerically studied by using Large Eddy Simulation. Cyclic boundary conditions are imposed on the velocity and pressure in the downstream and spanwise directions, while the no-slip boundary condition is imposed on the walls. Both the Smagorinsky model and One-equation modeling are applied, and from a comparison between the computed results, the importance of the diffusion term in SGS turbulent energy balance is pointed out.
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Hideaki Monji, Shigeki Morioka
1985 Volume 54 Issue 8 Pages
2866-2873
Published: August 15, 1985
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Viscous homogeneous two-phase liquid-metal flow in an open circuit MHD channel is solved by the method of matched asymptotic expansions with respect to the reciprocal of Hartmann number, in order to make clear the mechanism of the boundary-layer loss, to estimate its order, and to find some methods to reduce it. It is shown that the flow velocity in the core region is effectively controled by the Hartmann boundary-layer on the insulating walls. The solution of the Hartmann boundary-layer shows clearly how the distribution of the void fraction, the wetness of the liquid-metal against the wall and the aspect ratio of the channel cross-section influence the boundary-layer loss. The order of the boundary-layer loss is estimated by the equivalent external load resistance of the closed circuit MHD channel for invisid homogeneous two-phase liquid-metal flow.
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Moon-Uhn Kim, Wan-Kyun Chung
1985 Volume 54 Issue 8 Pages
2874-2882
Published: August 15, 1985
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Axisymmetric slow viscous flow due to the on-axis translation of two equal coaxial disks is investigated on the basis of the Stokes approximation. A formal expression for the flow field is obtained by sloving a mixed boundary value problem. The drag on the disk is expressed in power series of the ratio of the radius to the distance between the disks. Analysis and improvement of series for the drag are carried out. The asymptotic behavior of the drag is estimated, when two disks are nearly piled up.
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Haruyuki Irie
1985 Volume 54 Issue 8 Pages
2883-2893
Published: August 15, 1985
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The basic features of the nonadiabatic escape of charged particles from an axisymmetric mirror are studied by use of the equation of single particle motion. We obtain an expression for the change of the magnetic moment along a particle orbit in the mirror whose field strength varies sinusoidally in space. The theoretical values for the change are in good agreement with numerical results. The calculational results for the nonadiabatic escape are compared with the predictions of the existing theoretical model: “diffusion” model derived by B. V. Chirikov. The predictions agree well with our results outside the Störmer zone.
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Katsuji Chiyoda
1985 Volume 54 Issue 8 Pages
2894-2897
Published: August 15, 1985
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Magnetohydrodynamic (MHD) stability of an axially symmetric plasma is studied by use of the Mercier criterion. By introducing a non-orthogonal coordinate system, the Mercier criterion is presented in a form easy to apply. The criterion is applied to a tokamak plasma with an elliptical cross section. It yields a necessary criterion for stability, which reduces to the Shafranov-Yurchenko formula in the case of a circular cross section.
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Akira Tsushima
1985 Volume 54 Issue 8 Pages
2898-2904
Published: August 15, 1985
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The local characteristic of the Alfvén wave excited by a Stix coil is investigated in a radially inhomogeneous plasma. It is observed that the wave field of the standing axisymmetric Alfvén wave is enhanced and the polarization sense changes at the resonance layer. It is also observed that the phase velocity of the propagating axisymmetric Alfvén wave varies radially and corresponds to the local Alfvén velocity.
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Takashi Fujimoto
1985 Volume 54 Issue 8 Pages
2905-2914
Published: August 15, 1985
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Simple approximate formulas are proposed for the collisional-radiative ionization rate coefficient and recombination rate coefficient for hydrogen-like ions. These formulas are based on the continuation properties of various atomic quantities from the discrete states across the ionization limit to the continuum states. For an equilibrium plasma ionization ratio and population density distribution are discussed. The validity criterion for partial LTE (local thermodynamic equilibrium) is presented, which is much more stringent than Griem’s criterion. The case of non-hydrogenic ions is briefly discussed.
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Kazuhiro Takeuchi, Masahiro Wakatani, Hitoshi Hashimoto, Motoyasu Sato ...
1985 Volume 54 Issue 8 Pages
2915-2926
Published: August 15, 1985
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Ray tracing calculation of both the ordinary (O) mode and the extraordinary (X) mode using the cold plasma dispersion relation were carried out for the fundamental resonance (ω=ω
ce) and the second harmonic resonance (ω=2ω
ce) in a straight-heliotron configuration, where ω
ce denotes electron cyclotron frequency. Absorption coefficients are evaluated by the optical thickness along the ray trajectories without relativistic effects. In Heliotron E, dominant contribution to the heating by electromagnetic waves launched from the low field side is the O-mode for ω=ω
ce and the X-mode for ω=2ω
ce, when single path absorption is significant and mode mixing at wall reflection is negligible. Good heating efficiency requires adjustment of the cylotron resonance at the magnetic axis, which is consistent with the experimental data.
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Yoshiomi Kondoh, Kazuko Miyashita, Yutaka Tagaya, Shigemi Komagata, To ...
1985 Volume 54 Issue 8 Pages
2927-2933
Published: August 15, 1985
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Numerical results on the reversed-field-pinch (RFP) equilibria are presented with use of a partially relaxed state model derived from an energy principle. The relaxation process is assumed to be dominated by the helical tearing mode with a single helicity. The profiles of current densities concentrate more to the magnetic axis in the relaxed state which is dominated by the mode with the lower
n toroidal mode number. The maximum available β value with respect to the Suydam criterion is higher in the relaxed state dominated by the higher
n mode. Numerical results suggest that experimental RFP plasma has a tendency to relax to the partially relaxed state by the higher
n dominant mode.
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Shoji Kashida, Shoichi Sato
1985 Volume 54 Issue 8 Pages
2934-2939
Published: August 15, 1985
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The structure of a linear chain compound (CH
3)
3NHCdCl
3 was investigated at 355 K using a four-circle diffractometer. The structure belongs to the orthorhombic system, space group Pbnm. Unit cell dimensions are a=17.123 A, b=15.256 A, c=6.731 A and Z=8. The structure was refined by a block-diagonal least squares method. The obtained result in general agrees with the model reported previously. The disorder state of the trimethyl ammonium ions with unequal occupation propabilities is discussed. The mechanism of the phase transition from the room temperature (1×\sqrt3) phase to the high temperature (2×\sqrt3) phase is also discussed.
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Yasusada Yamada, Yukio Noda, Masaki Takimoto, Koichi Furukawa
1985 Volume 54 Issue 8 Pages
2940-2947
Published: August 15, 1985
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A microscopic model has been proposed which reproduces the extra-ordinary characteristics of the diffraction pattern observed in the premartensitic phase of TiNi. The modulated lattice relaxation (MLR) model is constructed on the two basic assumptions: (i) existence of sharp dip in phonon dispersion surface of the host lattice (ii) existence of a particular type of defects. In this system, the host lattice distorts giving rise to modulated lattice relaxation extending around the defect. The diffraction effect due to such MLR produces incommensurate superlattice reflections and a uniform shift of the peak positions from the commensurate value towards (or away from) the origin of the reciprocal space has been obtained, which is consistent with the observations. A microscopic mechanism of non-diffusional phase transitions is discussed on the basis of the proposed model.
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Yukio Morii, Masashi Iizumi
1985 Volume 54 Issue 8 Pages
2948-2954
Published: August 15, 1985
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The dispersion relation of [110] TA
1 phonon (
e⁄⁄[1\bar10]) of β
1-phase Cu
69.2Al
25.4Ni
5.4 was measured extensively at 261, 295 and 372 K by neutron scattering technique. It was found that the dispersion surface of the transverse acoustic mode has a pronounced valley along the [110] axis. The temperature dependence of the phonon energy shows a partial softening of the phonon mode. An anomalous dip of the dispersion curve was observed around
q=(2⁄3)
qmax on the [110] axis. Interplaner force-constant analysis revealed that the lattice dynamics of the crystal indicates dual instabilities both to the 2H and 18R type martensites. Quasielastic scattering was investigated on and in the vicinity of the [110] axis. Peaks attributable to the 2H and 18R martensites were observed as functions of temperature, which also indicates that 2H and 18R are competing.
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Yukio Saito, Ganji Tabe
1985 Volume 54 Issue 8 Pages
2955-2962
Published: August 15, 1985
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An Ising model with nearest neighbor antiferromagnetic and next nearest neighbor ferromagnetic interactions is studied by the phenomenological renormalization method. The phase transition to the \sqrt3×\sqrt3 structure is of the second order for weak fields, and the critical exponents
yT≅1.2 and η≅0.30 are consistent with the conjectured values of the 3-state Potts model. Beyond a tricritical point the transition becomes of the first order for strong fields. The tricritical exponent
yT, t≅1.73 and η
t≅0.21 are also in agreement with the 3-state Potts tricritical values
yT,t3P=12⁄7 and η
t3P=4⁄21. The XY-like phase transition at zero fields, which was obtained by the Monte Carlo simulations, is not found in the present calculation.
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Mamoru Yamashita, Osamu Tamada
1985 Volume 54 Issue 8 Pages
2963-2969
Published: August 15, 1985
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A phase boundary between chiral smectic C phase (Sm C
*) and smectic C phase (Sm C) is studied on the basis of a concept soliton, or kink, of an order parameter. A coupling between a tilt angle and an azimuthal one of the order parameter is important in the vicinity of transition point between Sm C
* and Smectic A. There, 6π- and 10π-solitons are found in addition to the ordinary 2π-soliton. An excitation energies of the formers are smaller than that of the latter, in agreement with an expected attractive interaction between solitons.
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Michiyoshi Tanaka, Hiroto Takayoshi, Masayoshi Ishida, Yasuo Endoh
1985 Volume 54 Issue 8 Pages
2970-2974
Published: August 15, 1985
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The chirality of the intermetallic compound MnSi has been determined by the convergent-beam electron diffraction to reveal the specific relation between the chirality of the crystal and helicity of its helical spin density wave. It has been found that the crystals have the left-handed chirality. The left-handed crystal means that Mn and Si atoms occupy the positions reported by Borén (Arkiv. Kemi. Mine. Geol.
11A (1933) No. 10, 1) but the left-handed coordinate system should be adopted to describe the atomic positions in the unit cell.
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Masayoshi Ishida, Yasuo Endoh, Setsuo Mitsuda, Yoshikazu Ishikawa, Mic ...
1985 Volume 54 Issue 8 Pages
2975-2982
Published: August 15, 1985
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Recent theoretical and experimental studies have shown the single handed helicity of the helical spin density wave in MnSi. In order to determine unambiguously the sense of the helicity we have carried out detailed experiments using pulsed polarized neutrons. Combining the result with that of the experiment on the crystal chirality, we have determined the left-handed or anticlockwise helicity for the left-handed chirality of the crystal symmetry. This leads to the positive sign of the antisymmetric exchange interaction in the left-handed chirality.
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Kimihiko Imura, Kiyoshi Kawamura
1985 Volume 54 Issue 8 Pages
2983-2995
Published: August 15, 1985
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A simple model of elemental semiconductors is presented, in which certain electronic levels are isolated within the forbidden gap under the plastic deformation. The dangling bond states arise from the local topology at the edge site. The lengthening of the nearest neighbor separation at the core region is responsible for another discrete levels within the gap whereas the shortening reduces the local density of states within the band in the vicinity of the edge site. These behaviors are explained in unified version by the local change of bonding-antibonding splitting.
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Daijiro Yoshioka, Hidetoshi Fukuyama
1985 Volume 54 Issue 8 Pages
2996-3003
Published: August 15, 1985
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A simple model is presented to describe superconductor-semiconductor phase transition for a binary alloy system. The model consists of randomly mixed two sites with different site energies and on site attractive interaction between electrons. The site energy difference is treated by the coherent potential approximation. The attractive interaction, which is treated by mean field approximation, stabilizes either the semiconductor phase, or the superconductivity depending on the choice of parameters. Applicability of this model to BaPb
1−xBi
xO
3 is discussed.
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Kitomi Tsutsumi, Tsuyoshi Tamegai, Seiichi Kagoshima, Masatoshi Sato
1985 Volume 54 Issue 8 Pages
3004-3011
Published: August 15, 1985
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The response of the charge-density wave (CDW) in K
0.30MoO
3 to pulsed electric fields is investigated in two types of samples, namely, the switching and the non-switching ones. The response in the switching sample is different from that in the non-switching sample and is quite complicated. Its origin is discussed in relation to the deformation of the CDW. In addition, the temperature dependence of the threshold field
ET is measured by the pulse method. Both types of samples show no maximum of
ET around 100 K reported by Dumas
et al.
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A. Tawfik, M. I. Abd El-Ati, F. M. El-Ashry, M. M. Abou Sekkina
1985 Volume 54 Issue 8 Pages
3012-3017
Published: August 15, 1985
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Several measurements have been undertaken on monoclinic zirconia refractory comprising the temperature dependence of DC electrical conductivity, infrared (IR absorption spectra) and Cu–K
α X-ray diffraction patterns (XRDP) before and after exposure to various absorbed gamma doses (10
5–10
8 rad). Promising results are obtained which hold good with one another explaining the interaction mechanism of ionizing radiation with monoclinic zirconia investigated. From conductivity measurements, the activation energies for carrier liberation are evaluated. The IR absorption spectra measurements are proved to be more sensitive and fast tool to detect the radiation damage than by X-ray diffraction method.
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Yoji Koike, Masami Okamura, Tetsuo Fukase
1985 Volume 54 Issue 8 Pages
3018-3028
Published: August 15, 1985
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For various kinds of thick granular Bi films, conductivity and magnetoresistance (MR) have been measured at low temperatures down to 0.05 K in magnetic fields up to 84 kOe. Corresponding to the degree of disorder in a sample, systematic results have been obtained at low temperatures. For samples of low resistivity, conductivity with
T1⁄2 dependence and anomalous positive MR appear. These are well explained by the three-dimensional weak localization theory taking account of spin-orbit interaction. The inelastic scattering time shows
T−3⁄2 dependence. For samples of high resistivity, large change of conductivity with log
T dependence and large positive MR with log
H dependence are observed. For the sample of the highest resistivity, the conductivity changes more rapidly than log
T. The MR is positive and rather large. This saturates and slightly decreases in high magnetic fields at very low temperatures.
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Kensei Ehara, Kikuo Cho, Akio Yoshimori
1985 Volume 54 Issue 8 Pages
3029-3041
Published: August 15, 1985
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Frenkel excitons localized at the surface of a cubic Bravais lattice are investigated theoretically in terms of a simple model. The dipole-dipole interaction is expressed in a planewise form and it is argued that the interaction between two planes consists of two components, short-range and long-range interactions, each of which is related to the Lorentz local field and the macroscopic electric field, respectively. Dyson’s equation for the Green’s function is solved in the wave number space. The surface excitons are shown to split into two levels and the criteria for their existence are clarified. In some cases the oscillator strength of the surface excitons depends strongly on the polarization of the excitation light.
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Akiko Natori, Takahisa Ohno, Atsushi Oshiyama
1985 Volume 54 Issue 8 Pages
3042-3050
Published: August 15, 1985
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We propose a simple layer model in which real atomic configurations are simulated by multi-layers with homogeneous electron density on each layer, in order to investigate work function of alkali-atom adsorbed graphite. Charge transfer from an alkali-atom layer to graphite layers is determined within the model by minimizing total energy. The calculated decrease in work function of graphite upon alkali-atom adsorption agrees satisfactorily with the experimental data.
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Masanori Sugahara, Masahiko Nagai, Naoyuki Ando, Nobuyuki Yoshikawa, Y ...
1985 Volume 54 Issue 8 Pages
3051-3060
Published: August 15, 1985
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Experimental study is made on the behavior of long-bridge devices made of granular superconductor. The observed result corroborates that the device works on physical principle dual to Josephson effect.
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Shoichi Nagata
1985 Volume 54 Issue 8 Pages
3061-3066
Published: August 15, 1985
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A systematic investigation of the thermal fluctuation effects has been carried out on Pb–Ag–Pb (superconductor-normal metal-superconductor) Josephson junctions with special emphasis on the critical current
Ic(
H) in magnetic fields. Thick normal-metal barriers (∼15000 Å) are prepared in order to suppress the Josephson coupling energy between the two superconductors. Thermal fluctuations can significantly break the superconducting phase coupling and then lead to a decrease of the oscillation amplitude of
Ic(
H). In the presence of strong fluctuations, the envelope of the maxima in the Fraunhofer diffraction pattern is proportional to 1⁄
H2 and not to 1⁄
H as in the absence of thermal fluctuations. The experimental results are in agreement with theoretical predictions of Ivanchenko and Zil’berman.
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Hiroshi Fukuma, Takemi Komatsubara, Takashi Suzuki, Emanuel Kaldis, Ta ...
1985 Volume 54 Issue 8 Pages
3067-3075
Published: August 15, 1985
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From detailed magnetization measurements, it becomes clear in the NNS state of EuSe that N and S-site spins form a canted state for applied field inclined from the (111) plane. From this canting angle, we can estimate the biquadratic interaction
j1. Transition fields,
H2 and
H3, together with the paramagnetic Curie temperature, give the values of
J1,
J2 and
J3 definitely. Using these values, we calculate the anisotropic magnetization process in excellent agreement with experiment. Zero point reductions of magnetization both in NNS and NNN states are observed to be large. Moreover, the field and the temperature dependences of the magnetization in the NNN region are large. Introducing the pseudo-dipole term, we calculate the zero point reduction in the NNN state consistently with the observed one. Softening of the magnon is the origin of the unusual behaviour of the magnetization.
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Jun Takeuchi, Takashi Ito, Masahiro Oka
1985 Volume 54 Issue 8 Pages
3076-3083
Published: August 15, 1985
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Ultrasonic attenuation and sound velocity have been measured for a single crystal of the Gd
70Y
20Lu
10 alloy in external magnetic fields up to 6.5 kOe and over the temperature range 160–230 K which includes the ferromagnetic and screw antiferromagnetic states. Several anomalies observed in attenuation and velocity measurements are analyzed together with the magnetization data to construct the magnetic phase diagram. The large peak in attenuation and the large drop in velocity observed only on the warming-up process are attributed to the reorientation of the spins inside and just outside of the domain wall. An attenuation peak observed within the region of the fan phase is interpreted as the peculiar one originating from the spin structure of the fan phase.
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Hideki Yoshizawa, Stephen M. Shapiro, Takemi Komatsubara
1985 Volume 54 Issue 8 Pages
3084-3090
Published: August 15, 1985
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Inelastic neutron scattering measurements on MnP reveal that the spin wave gap vanishes at the paramagnetic-ferromagnetic phase boundary in a manner predicted by the transverse field Ising model. The occurrence of the tricritical point in a temperature-field phase diagram is strongly related to the temperature-driven change of the phenomenological parameter
P≡
J2z⁄
J1z which describes the competition between the effective nearest and next-nearest-neighbor exchange interactions. The itinerant nature of the magnetism of this compound is emphasized as a possible origin of the temperature dependence of
P. The tricritical point is most likely a Lifshitz Point as pointed out in detailed measurements of the phase diagram by Shapira
et al.
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Kazuyoshi Takeda, Kiichi Amaya, Youichi Murakami
1985 Volume 54 Issue 8 Pages
3091-3097
Published: August 15, 1985
Released on J-STAGE: June 01, 2007
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The characteristic temperature dependence of magnetic heat capacities
Cm of XY ferromagnetic spin systems in one and two dimensions has been observed in CsNiF
3 and graphite-CoCl
2, respectively. The value of
Cm of CsNiF
3 has been shown to depend linearly on temperature
T at low temperatures, and reproduced by the theoretical values for an XY ferromagnetic chain with the reported value of exchange constant
J⁄
kB=11.8 K and with spin value
S=1. While, in the CoCl
2 compound
Cm has been found to obey
Cm=
m(
J)
T2 which agrees with the spin wave theory for an XY ferromagnet in two dimensions with
J⁄
kB=9.7 K. The thermal behaviour of these compounds reflects magnetic excitations intrinsic to the XY system, making a typical contrast with the case for the Heisenberg system.
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Fusatoshi Arae, Hisao Arimune, Fumihisa Ono, Osamu Yamada
1985 Volume 54 Issue 8 Pages
3098-3105
Published: August 15, 1985
Released on J-STAGE: May 29, 2007
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The first magnetocrystalline anisotropy constant
K1 was determined by means of torque method for 26.5, 28.3, 29.9, 30.9, 33.2 at%Pt–Fe and 31.9, 34.2 at%Pd–Fe disordered alloys and the temperature and field dependences of
K1 of these alloys were compared with those of Fe–Ni Invar alloys. Anomalous temperature and field dependences of
K1 were found below room temperature for all Fe–Pt disordered alloys and for 31.9 at%Pd–Fe alloy in the low temperature region. These anomalous behaviors of
K1 seems to be caused by the contribution of uniaxial anisotropy of f.c.t. clusters.
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Koichi Maezawa, Hiroaki Takeuchi, Kikuo Ohi
1985 Volume 54 Issue 8 Pages
3106-3110
Published: August 15, 1985
Released on J-STAGE: June 01, 2007
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ESR spectra of γ-ray irradiated LiKSO
4:Se have been measured. The ESR lines of SeO
4− in the room temperature phase split into two branches in the intermediate phase from −75°C to −23°C on heating run and the mirror symmetry appears in the
ac plane and the
bc plane. The principal values and the directions of the g-tensor have been determined at room temperature and at −60°C on heating run. The results indicate that the space group of the intermediate phase is
P31
c. A model of the twin structure is discussed.
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Kazuo Tsuru, Norikiyo Uryû, K. Le Dang, P. Veillet
1985 Volume 54 Issue 8 Pages
3111-3128
Published: August 15, 1985
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The nuclear spin-lattice and transverse relaxation times were calculated for a two-dimensional ferromagnet with single-ion anisotropy, using the renormalized spin-wave development. The experimental transverse relaxation rate of
53Cr nuclei was fairly explained by the Suhl-Nakamura interactions and the two-magnon process. The calculated spin-lattice relaxation due to three-magnon process with exchange enhancement led to an unusual result: the enhancement factor is as high as 29.4 at 25 K i.e. much more than for an easy-axis ferromagnet and a three-dimensional one.
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Shozo Sawada, Toshihisa Yamaguchi, Haruhiko Suzuki, Fuminao Shimizu
1985 Volume 54 Issue 8 Pages
3129-3135
Published: August 15, 1985
Released on J-STAGE: June 01, 2007
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Thermal, dielectric and dilatational measurements were performed to study the phase transitions in ferroelectric {N(CH
3)
4}
2ZnCl
4. The temperature dependence of triple
D-
E hysteresis loop in ferroelectric Phase III (3.3∼6.0°C,
C2v9-
P2
1cn) was observed in detail. The crystal is paraelectric along the
b and
c directions. A remarkable contraction of the lattice is seen in Phase V (−112∼−92°C,
C2h5-
P12
1⁄
c1). Calculated pressure-coefficients of transition temperatures were compared with the measured ones.
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Shozo Sawada, Toshihisa Yamaguchi, Haruhiko Suzuki, Fuminao Shimizu
1985 Volume 54 Issue 8 Pages
3136-3142
Published: August 15, 1985
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Dielectric properties of ferroelectric {N(CH
3)
4}
2CoCl
4 were measured in detail, covering its all transition points. The triple
D-
E hysteresis loop in Phase III (4.6∼7.1°C,
C2v9-
P2
1cn) was ascertained. The lattice distortion of this ferroelectric was determined along the three crystallographic axes by a differential-transformer type dilatometer. The pressure-coefficient of transition temperature was discussed.
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Yoshiki Wada, Tadaoki Mitani, Masahiro Yamashita, Takao Koda
1985 Volume 54 Issue 8 Pages
3143-3153
Published: August 15, 1985
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Polarized reflection and luminescence have been measured for the single crystals of [MA
2][MX
2A
2](ClO
4)
4 (M=Pt, Pd, X=Cl, Br, I and A=ethylenediamine, cyclohexanediamine). The strong absorption bands due to the charge-transfer (CT) exciton transitions between the mixed-valent metal ions have been investigated in detail in the visible or infrared energy regions. The dependence of the CT excitation energies on the species M and X is shown to be consistent with the prediction by the Peierls-Hubbard model which incorporates the effect of the electron-electron correlation on inter-metal sites. The oscillator strength of the CT excitons are observed to be enhanced by substituting heavier halogen ions. This enhancement is interpreted by a halogen-linked super-transfer mechanism. The unusually large values of the oscillator strength can be qualitatively explained in terms of the trimer CT model.
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Hisashi Katahama, Shin-ichi Nakashima, Akiyoshi Mitsuishi, Bogdan Palo ...
1985 Volume 54 Issue 8 Pages
3154-3161
Published: August 15, 1985
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Raman spectra of various CdI
2 polytypes have been measured at liquid He temperature. Several folded modes of the E symmetry optical branch have been observed in higher polytypes. The dispersion curve of the E symmetry branch in the [00ξ] direction has been obtained from the experimental frequencies of the folded modes. The pressure dependence of the Raman active modes has been also measured. These results are analyzed by using a linear chain model and a polarizable ion model. The analysis indicates that the long range forces contribute little to the interlayer forces and that the difference in long range forces as well as the short range forces among the polytypes is very small.
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Akira Namiki, Hideki Fukano, Takaaki Kawai, Yukio Yasuda, Tetsuro Naka ...
1985 Volume 54 Issue 8 Pages
3162-3167
Published: August 15, 1985
Released on J-STAGE: June 01, 2007
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Dependence of laser-induced desorption on both substrate temperature and emission angle have been studied in CdS by using the pulse mass counting method. The effective translational temperature (
Ttrans) of particles ejected toward the angle of 0° from the surface normal is much higher than that toward 45°C. The
Ttrans of each particle, S, S
2 and Cd, is different among them.
Ttrans does not exhibit the surface temperature even when the time-of-flight spectra can be fitted with a Maxwellian velocity distribution. Arrhenius plots of desorption yields for the substrate temperature before laser irradiation show rather complicated features. Estimation of the temperature rise at surface by calculating the thermal diffusion equation gives the linear relationship in the Arrhenius plot. The enthalpy for desorption is estimated to be 0.44±0.1 eV. This value is considerably smaller than that (2.2 eV) obtained in the free vacuum vaporization (ref. 13), suggesting the contribution of the electronic excitation effect.
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