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Tohru Ogawa
1985 Volume 54 Issue 9 Pages
3205-3208
Published: September 15, 1985
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A 3-D Penrose transformation is found. The expansion rates, τ
3 in linear dimension and τ
9 in volume, are by far the larger than τ and τ
3 respectively ever believed. The transformation decides only the skeleton uniquely, leaving some other degrees of freedom undecided. It strikingly differs from the deterministic 2-D case. Many other properties are common with the 2-D case. This transformation is helpful in understanding the quasi-crystal structure about which most of discussions so far were based on some incomplete or wrong knowledge. The beautiful structure of the transformation inspires to speculate the possibility of providing many theoretical tools to discuss various fundamental problems. Some details of the transformation is given in the form of an instruction for the model construction in Appendix.
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Hajime Hirooka, Masuyoshi Kurokawa, Nobuhiko Saito
1985 Volume 54 Issue 9 Pages
3209-3212
Published: September 15, 1985
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The eigenvalues of an integrable hamiltonian of two degrees of freedom can be expressed as
E(
n,
m) with
n,
m integers. Although
E(
n,
m) are regular with respect to
n (or
m) when
m (or
n) is held fixed, the sequence of
E(
n,
m) arranged in the order of magnitude looks irregular. We want to give an algorithm for extracting regularity from the level spacings or the energy levels with disguised irregularities in an integrable system. Further a method is proposed to distinguish true irregularities in non-integrable system from disguised ones in integrable system.
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Katsushi Arisaka, Takaaki Kajita, Masatoshi Koshiba, Masayuki Nakahata ...
1985 Volume 54 Issue 9 Pages
3213-3216
Published: September 15, 1985
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With a 3000 ton water Cerenkov detector operated 2700 m.w.e. underground, 103 fully contained events were observed during a live time of 343 days. Most of the events are well interpreted as due to ν interactions. Four multi-ring events survive after applying criteria for nucleon decay. The lower limits on τ⁄
B obtained from these data exceed 10
31 yr (90% C.L.) for most of the possible decay modes.
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Kaoru Kimura, Tatsuo Hashimoto, Kunio Suzuki, Katsuhisa Nagayama, Hiro ...
1985 Volume 54 Issue 9 Pages
3217-3219
Published: September 15, 1985
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Electron microscopy has shown that in rapidly solidified Al-(14–20) at.%Mn alloys a new metastable phase of a quasicrystalline phase with the icosahedral symmetry, which was first discovered by Shechtman
et al. (Phys. Rev. Lett.
53 (1984) 1951), is formed but with a considerable amount of fcc Al second phase in alloys with lower Mn content. From the change with Mn content of the intensity of fcc Al lines in the powder X-ray diffraction spectrum, the stoichiometry of the Al–Mn quasicrystalline phase is concluded to be nearly Al
4Mn (∼20.5 at.%Mn), being at variance with the reported composition of Al
6Mn.
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Hikaru Kawamura
1985 Volume 54 Issue 9 Pages
3220-3223
Published: September 15, 1985
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Phase transition of the frustrated Heisenberg antiferromagnet on the layered-tirangular (or hexagonal) lattice is studied with use of a symmetry argument and Monte Carlo simulations. A finite-size scaling analysis strongly suggests the occurrence of a second order transition of a new universality class characterized by the exponents α\simeq0.4, β\simeq0.25, γ\simeq1.1 and ν\simeq0.53.
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Mamoru Chikamatsu, Hidetaro Abe
1985 Volume 54 Issue 9 Pages
3224-3227
Published: September 15, 1985
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After complete removal of the pressure on (C
2H
5NH
3)
2CuCl
4, an interchange within in-plane spin axes is recognized by magnetic measurements and that of crystalline axes by X-ray analysis. The condition indispensable for this phenomenon is the application of external magnetic field (2∼3 kOe) along its second easy axis under hydrostatic pressure (∼7 kbar) at liquid helium temperature. A successive process along the newly built second easy axis results in a recovery to the initial state of spin axes.
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Hiroo Oya, Nobuhiko Wada
1985 Volume 54 Issue 9 Pages
3228-3229
Published: September 15, 1985
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The specific heat of softly packed ultrafine particles of silver was measured by means of scanning calorimetry in the temperature range from 50°C to 200°C.
Measurement was done six times with a specimen in the same temperature range and the same value of the specific heat almost independent of the temperature was obtained except for the case of the first measurement in which the exothermic reaction due to sintering of particles was observed.
Measured specific heat was larger than that of bulk silver by 3–5 J/mol·K. This excess value is interpreted in terms of the lattice vibration modified by the interation with the neighbor grains such as van der Waals’.
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Hiroyuki Deguchi, Naotake Morita, Yoshitaka Moriyasu, Kazuyoshi Takeda ...
1985 Volume 54 Issue 9 Pages
3230-3231
Published: September 15, 1985
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Heat capacities of molecular hydrogen H
2 adsorbed in interlayer space of N
+(CH
3)
4-montmorillonite have been measured at temperatures between 2 K and 20 K. An anomalous λ-type peak is observed at 7.6 K in the virgin run of the measurement for H
2 concentration less than 5×10
−4 mol/gr.
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Hironobu Ikeda, Yasuo Endoh, Setsuo Mitsuda
1985 Volume 54 Issue 9 Pages
3232-3235
Published: September 15, 1985
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We present direct evidence for the two-dimensional magnetic ordering in high stage (2nd and 3rd) compounds of CoCl
2-graphite intercalation using neutron diffraction technique. Experiments from the high stage compounds show interesting features that at the lower transition temperature (
Tc1) the systems undergo a three-dimensional antiferromagnetic transition but above
Tc1 the scattering is characteristic of the full two-dimensional magnetic correlations. This suggests that the intermediate phase between two successive phase transitions at
Tc1 and
Tcu, which had been observed in the high stage CoCl
2-graphite intercalation compounds by earlier magnetic measurements, is a two-dimensional one possibly with a XY character.
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Yoshio Kitaoka, Hironobu Arimoto, Yoh Kohori, Kunisuke Asayama
1985 Volume 54 Issue 9 Pages
3236-3239
Published: September 15, 1985
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From the
29Si Knight shift (K) and the nuclear relaxation rate (1⁄
T1) measurements, CeRu
2Si
2 is demonstrated to be the non-magnetic Kondo lattice compound with the Kondo temperature
TK=12 K which exhibits a huge anisotropy of the magnetic properties. The Knight shift
K⁄⁄ parallel to the tetragonal
c-axis shows a similar temperature dependence to the measured susceptibility with a maximum around 12 K, while
K⊥ perpendicular to the
c-axis is almost temperature independent with
K⁄⁄⁄
K⊥=30 at 4.2 K. 1⁄
T1⊥ is larger by about 3 times than 1⁄
T1⁄⁄ and both decrease as temperature lowers below 12 K, changing from the temperature independent behavior at higher temperature. It has been found that 1⁄
T1⊥ obeys the Korringa relation with
T1⊥T=1.0 sec K below
T*\simeq8 K, demonstrating that the Fermi liquid state has emerged just below
TK=12 K.
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Yuji Sugimoto, Satoru Ohta, Shunichi Yuri, Masuichi Tamaki, Shuichiro ...
1985 Volume 54 Issue 9 Pages
3240-3243
Published: September 15, 1985
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Magnetizations and magnetic susceptibilities are investigated on the defect NiAs-type (Cr
1−xTi
x)
3Te
4 [0.00≤
x≤1.00]. A temperature-independent paramagnetic susceptibility [1.8×10
−4 emu/mole] is found in Ti
3Te
4. The Curie temperature
Tc(
x), the canted spin transition temperature
Tt(
x) and the Weiss constant θ
p(
x) decrease as
x increases. A downward convex is observed around
x=0.67 on the
Tc(
x) vs
x curve. The spontaneous magnetization at 4.2 K is still retained at the sample with
x=0.95. The observed value of d
Tt(
x)⁄d
x has the negative sign, and those of θ
p(
x) positive ones. These features are compared with the results on (Cr
1−wRh
w)
3Te
4 and (Cr
1−uV
u)
3Te
4 in which spin-glass like states have been found.
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Kunihiko Morimoto, Kenji Shimomura
1985 Volume 54 Issue 9 Pages
3244-3247
Published: September 15, 1985
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Spin-lattice relaxation times
T1ρ of protons (
1H) in the rotating frame were determined in ammonium perchlorate NH
4ClO
4 between 556 K and 125 K. The temperature dependence of
T1ρ shows two minimum values 1.5 sec at about 476 K and 0.94 sec at 238 K for an
rf field H
1=2.1 gauss. The origins of the minima
T1ρ are attributed to the motion of oxygen atoms
17O of natural abundance (0.037%). Oxygen atoms affect
T1ρ of protons in different two ways. The minimum of
T1ρ at higher temperature is due to the cross relaxation between
1H and
17O spins, while that at low temperature due the the reorientation of ClO
3-ions which modulates the dipolar interaction between
1H and
17O and also due to the cross relaxation between
1H and
17O. The value
e2qQ⁄
h=12.3 MHz was determined for
17O in ClO
4-ion.
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Yoshitomo Karaki, Hiroyuki Deguchi, Kiichi Amaya
1985 Volume 54 Issue 9 Pages
3248-3249
Published: September 15, 1985
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Adiabatic demagnetization with fast sweep rate of 5×10
9 Oe/sec is performed on Cs
3CoCl
5 by the superposition of a stationary and a pulsed magnetic field with opposite direction. The first observation of negative magnetization of an electronic spin system in a laboratory frame is reported.
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Masaaki Takashige, Hikaru Terauchi, Yuichi Miura, Sadao Hoshino
1985 Volume 54 Issue 9 Pages
3250-3253
Published: September 15, 1985
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The mixed crystal Rb
1−x(NH
4)
xH
2PO
4 shows ferroelectricity for small
x and antiferroelectricity for large
x. The frequency dispersion of the dielectric constant was studied in the concentration range 0.5≤
x. The low-frequency dispersion was found for 0.5≤
x≤0.8 below 40 K. From the results, the phase diagram was obtained. Around
x=0.75, a re-entrant glasslike phase with the dispersion of the dielectric constant was found.
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Mikihiko Ikezawa, Takao Nanba, Itsuro Yamamoto, Xiao-lei Wang
1985 Volume 54 Issue 9 Pages
3254-3256
Published: September 15, 1985
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Anisotropic reflectivity spectra of an Ag
2F crystal have been investigated for linearly polarized light with the electric vectors both parallel and perpendicular to the
c-axis. Steep rises of the Drude-type reflectivity are found at 2.7 and 0.9 eV for
E⊥
c and
E⁄⁄
c spectra, respectively, and are interpreted as being due to the anisotropy in plasma frequency of electrons in the conduction band. In the spectrum for
E⊥
c, an extremely sharp dip of the reflectivity is observed at 2.9 eV which is similar to the absorption window of silver metal.
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Haruki Nakamura, Katsuichiro Komatsu, Hideaki Umeyama
1985 Volume 54 Issue 9 Pages
3257-3260
Published: September 15, 1985
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A method is described for visualizing electrostatic complementarity between a guest ligand and a host enzyme by using molecular graphics and drawing a correlation map. First, two kinds of electrostatic potentials were calculated and illustrated on the surface of the guest molecule. One is due to the host enzyme and the other is due to the guest molecule itself. Second, the correlation between these two molecular surfaces was calculated and illustrated. Simultaneously, the correlation map was given with a well-defined correlation coefficient. This method provides a helpful tool for understanding the specific electrostatic recognition geometrically and quantitatively.
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Noriko Saitoh
1985 Volume 54 Issue 9 Pages
3261-3267
Published: September 15, 1985
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The Bäcklund Transformation (BT) and Hamiltonian formalism (HF) of a Generalized Toda Lattice are derived. Here the BT and HF of the KdV equation are discussed on the same basis as in the Toda lattice, in a clear manner without violating integrability.
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Kazuyosi Ikeda
1985 Volume 54 Issue 9 Pages
3268-3276
Published: September 15, 1985
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The model of one-dimensional gas is proposed for which the intermolecular force consists of the hard-core repulsion, the short-range attraction or repulsion given by a nearest-neighbour square potential and the infinitely-long-range attraction given by the potential −2
a⁄
L (
a=positive constant,
L=length of the gas). The equation or state and the thermodynamic functions for this model (in the limit
L→∞ with length per molecule fixed) are exactly calculated from the partition function. Generalization of the short-range force in this model is discussed.
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Kazuyosi Ikeda
1985 Volume 54 Issue 9 Pages
3277-3288
Published: September 15, 1985
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The model of one-dimensional gas (proposed in the preceding paper I) of molecules with hard cores, with short-range interactions given by a nearest-neighbour (repulsive or attractive) square potential and with infinitely-long-range interactions given by the attractive potential −2
a⁄
L (
a=positive constant,
L=length of the gas,
L→∞ with length per molecule fixed) is rigorously treated at the absolute zero; especially its phase transitions are investigated. It is deduced that, at the absolute zero, this model in the case of
repulsive short-range interaction exhibits two transitions (the gas-liquid and the liquid-solid transition) if the long-range attraction is weak enough, and exhibits only one transition (the gas-solid transition) if the long-range attraction is strong enough, and this model in the case of
attractive short-range interaction exhibits only one transition (the gas-solid transition).
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Toru Hasegawa, Shigeki Tasaka, Yoshihiro Sato, Hisahiko Sugimoto, Kuni ...
1985 Volume 54 Issue 9 Pages
3289-3296
Published: September 15, 1985
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1.88 GeV/n Fe beams of LBL were vertically irradiated to the chambers composed of a pile of plastic track detector (CR-39) and nuclear emulsion plates. The charge number of projectile fragments in Fe interactions was carefully examined by use of CR-39. The angular distributions of emitted alpha particles have been investigated for several ranges of charge numbers of projectile fragments. The result of analysis shows that the emission angle distribution of alpha particles at large angles cannot be explained by the single mechanism of the fragmentation from a clean cut spectator. For events of central collisions with smaller charges of projectile fragments, the effective temperature for the production of alpha particles turns out to be much higher than that of the evaporation theory. The results are applied to the calibration of primary energy estimation by the opening angles of alpha particles.
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Kozo Ando, Keishi Ishii
1985 Volume 54 Issue 9 Pages
3297-3304
Published: September 15, 1985
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The XUV spectrum of molybdenum was observed with a low-inductance vacuum spark, by use of a 10.7 m grazing-incidence spectrograph. In the present work, 33 lines for 3d
9-3d
84f transition and 31 levels of 3d
84f configuration in Mo XVI were identified. Among them, 13 lines and 22 levels are newly observed. The identifications were obtained with the aid of theoretical calculation based on the Slater-Condon theory of atomic structure. Observed and theoretical spectra are given in figures, and energy levels in a diagram. Energy levels and wavelengths with weighted oscillator strength are also presented in tables.
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Yasuo Hashizume
1985 Volume 54 Issue 9 Pages
3305-3312
Published: September 15, 1985
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The nonlinear pressure wave propagation in a straight thin elastic tube containing an inviscid incompressible fluid is considered using the shell theories which are extended to the second order of magnitude of deformations. The nonlinear effects being taken into account are due to the convective motion of fluid, nonlinear strains and stress-strain relations. Though our problems are considerably simplified by the shell theories, the resultant equations for the displacements of the middle surface are still complicated. Therefore, further considerations are confined to the asymptotic state in which the system of equations can be reduced to the Korteweg-de Vries (K-dV) equation and the relation between the multi-soliton solutions and peaking and steepening phenomena is discussed.
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Makoto Okamura
1985 Volume 54 Issue 9 Pages
3313-3320
Published: September 15, 1985
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Stability Characteristics of weakly nonlinear three-dimensional standing gravity waves on the surface of deep water are investigated on the basis of the Zakharov equation. It is found that the resonance curves and the instability domains in the three-dimensional standing waves are larger than those in two-dimensional standing waves, and generally the instability due to two-dimensional disturbances predominates over that due to three-dimensional ones. The maximum growth rate for the two-dimensional standing waves is shown to be about 30 percent larger than that for the two-dimensional limiting waves.
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Norihiko Nakauchi
1985 Volume 54 Issue 9 Pages
3321-3331
Published: September 15, 1985
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The energy spectrum equation of homogeneous axisymmetric turbulence for a conducting incompressible fluid under an imposed uniform magnetic field,
B0, is formulated by using the modified zero-4th-cumulant approximation. Since the magnetic Reynolds number is assumed to be small, the induced magnetic field,
b, around
B0 can be calculated by a quasi-static approximation.
Numerical calculations are made by assuming an initially isotropic state at the integral-length-scale Reynolds number
RL=60. Results show that the large imposed magnetic field,
B0, makes the turbulent field in the plane (
k·
B0)=0 (
k is wavevector) behave as expected from the theories of two-dimensional turbulence.
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Rida M. Mirie
1985 Volume 54 Issue 9 Pages
3332-3336
Published: September 15, 1985
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The solitary wave that is governed by several KdV type differential equations can take an unlimited amplitude values. In the case of a solitary wave at the interface of a two-layer fluid system these unlimited amplitude values are inconsistent with the physical dimensions of the system. As a result we consider an approximate set of differential equations which describes the solitary wave at the interface, and find that the highest possible amplitude is given by
Af=(−
R−σ
1⁄2)⁄(1+σ
1⁄2) where (−
R) is the ratio of depths and σ is the ratio of the fluids densities. This solitary wave is of depression (elevation) if σ is larger (smaller) than
R2. The interface displacement is given by an elliptic integral of the third kind. However, for particular relations between σ and
R, the interface can be written in terms of elementary functions which describe the KdV, MKdV, and shock-like profiles of limited amplitudes, respectively.
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Moon-Uhn Kim, Jae-Uk Kim
1985 Volume 54 Issue 9 Pages
3337-3341
Published: September 15, 1985
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Slow rotation of a thin circular annulus about an axis through the center of the annulus in an unbounded viscous fluid is investigated on the basis of the Stokes approximation. By using a general solution of the Stokes equations in cylindrical coordinates the problem is formulated as a set of triple integral equations which are reduced to a Fredholm integral equation of the second kind. It is shown that the annular disk is isotropic with respect to rotation about its center. By solving the Fredholm integral equation numerically, the couple on the annulus is given graphically as a function of the ratio of the inner to outer radius.
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Mitsuhiro Shigeta, Tetsuya Sato, Brahmananda Dasgupta
1985 Volume 54 Issue 9 Pages
3342-3346
Published: September 15, 1985
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The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the anti-parallel magnetic field lines and localized in the neutral sheet excites a
streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width or smaller which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.
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Shobu Kaneko, Atsushi Kamitani, Akio Takimoto
1985 Volume 54 Issue 9 Pages
3347-3357
Published: September 15, 1985
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The analytic solutions to the Grad-Shafranov equation are obtained for a prolate and an oblate spheroidal plasma by using Hill’s vortex model. Effects of a toroidal magnetic field
B\varphi on the MHD equilibrium configurations are investigated by using these analytic solutions. When
B\varphi is stronger than that of the force-free configuration, the spheroidal plasmas in a vacuum magnetic field are shown to be unable in the MHD equilibrium. The several physical quantities on the equilibrium configuration are evaluated. The spheromak plasma is proved to be unstable if d
p⁄dψ≠0 and d
2V⁄dψ
2≥0 on the magnetic axis. Here
p is the pressure and
V(ψ) the volume surrounded by a magnetic surface of ψ=const. The equilibrium configurations of the spheroidal plasmas by using Hill’s vortex model are shown to satisfy the above conditions, i.e., to be unstable.
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Hajime Asano, Masayuki Umino, Yoji Hataoka, Yoshiaki Shimizu, Yoshichi ...
1985 Volume 54 Issue 9 Pages
3358-3361
Published: September 15, 1985
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The crystal structure of LaCu
6 has been determined by an X-ray precession method and Rietveld analysis on powder X-ray diffraction data. The crystal system is monoclinic (space group
P2
1⁄
c) with lattice parameters
a=5.143 Å,
b=10.204 Å,
c=8.144 Å and β=91.49°. The unit cell contains four formula units La
4Cu
24. The structure is a slight modification of the orthorhombic CeCu
6 structure accompanied by a monoclinic deformation and minor shifts of the atomic positions.
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Takashi Tonegawa, Koichi Takasaki, Makoto Kaburagi, Junjiro Kanamori
1985 Volume 54 Issue 9 Pages
3362-3375
Published: September 15, 1985
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An application of the method of geometrical inequalities to the rigorous determination of the ground state of the lattice gas model in which two kinds of particles interact by pairwise interactions of extended range is discussed. As an illustrative example we take the model on the one-dimensional lattice with first and second neighbor interactions, treating the whole region of particle densities, but imposing the condition that the
k-th (
k=1, 2) neighbor interaction constants between the same kinds of particles are equal and that the
k-th (
k=1, 2) neighbor interaction constant between different kinds of particles is half of those between the same kinds. It is found that seven types of ordered structures of particles appear as the ground states in this example.
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Akira Yoshihara, Takashi Suzuki, Tsutomu Yamakami, Tadao Fujimura
1985 Volume 54 Issue 9 Pages
3376-3384
Published: September 15, 1985
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The successive phase transitions in the layered perovskite compound (C
2H
5NH
3)
2FeCl
4 have been investigated through Brillouin scattering. The I–II phase transition is characterized by a large dynamical critical behavior and a strong Landau-Khalatnikov contribution to the C
66 elastic constant. In the phases III, IV and V, non-critical acoustic dispersion has been observed on the C
11 elastic constant. The present results suggest a tetragonal-orthorhombic-orthorhombic phase sequence for the I, II and III phases.
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Seiji Miyashita, Hikaru Kawamura
1985 Volume 54 Issue 9 Pages
3385-3395
Published: September 15, 1985
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Phase transitions in anisotropic Heisenberg antiferromagnets with nearest neighbour coupling constants (
Jx,
Jy,
Jz) on the triangular lattice have been investigated. In particular, for the case of Heisenberg-Ising model, |
Jz|>|
Jx|=|
Jy|>0, successive phase transitions due to orderings of
z components and of
xy components have been found. A non-trivial degeneracy is found both in the ground state and in harmonic excitations. Divergent-like behaviour of the uniform susceptibility in the
xy plane at low temperatures is found, which is supposed to be caused by the non-trivial degeneracy.
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Bin Okai
1985 Volume 54 Issue 9 Pages
3396-3400
Published: September 15, 1985
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Upon applying pressure on alkali halide model-crystals of B1 structure, the oscillation of TA[100] mode becomes unstable. Due to deformation of TA[100] mode, the repulsive force between the nearest neighbor ions is weakened, energy is lowered, and the instability sets in. For the discussion of onset of instability, the internal energy and Gibbs free energy lead to the same conclusion. For a finite deformation, the Gibbs free energy must be used.
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Masaru Komukae, Toshio Osaka, Tsutomu Kaneko, Yasuharu Makita
1985 Volume 54 Issue 9 Pages
3401-3405
Published: September 15, 1985
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The dielectric constants along the
c′ axis of Cs
3H(SeO
4)
2 and its deuterated crystal were measured in a temperature range from 5 K to 460 K. It was found that Cs
3H(SeO
4)
2 undergoes three phase transitions at 451 K, 364 K and 50 K. The dielectric constant of Cs
3H(SeO
4)
2 shows a small peak at 50 K, and it obeys the Curie-Weiss law above 50 K. The transition temperature (50 K) is increased to 168 K by deuteration, showing a large isotope effect, while other two transition temperatures do not change appreciably.
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Uichiro Mizutani, Shinji Ohta, Takeshi Matsuda
1985 Volume 54 Issue 9 Pages
3406-3414
Published: September 15, 1985
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The low-temperature specific heats (1.5–6 K) and the electrical resistivities (2–300 K) have been measured on liquid quenched Pd
0.33Zr
0.67H
x,Pd
0.35Zr
0.65H
x and Ni
0.35Zr
0.65H
x (0≤
x≤1.2) ternary metallic glasses. Low-temperature specific heat data showed a substantial reduction in both the superconducting transition temperature and the density of states at the Fermi level but an increase in the Debye temperature upon hydrogenation. The results can be interpreted on the basis of the fact that hydrogen atoms tend to be trapped in tetrahedral sites surrounded by Zr-atoms. The electrical resistivities in the range 30–300 K can be well fitted to an empirical equation ρ⁄ρ
0=
A+
B exp (−
T⁄
Δ) for all alloys studied. Attention is focused on the Mooij correlation in the resistivity range 200–300 μΩ·cm and also on the presence of a correlation between the characteristic temperature
Δ and the Debye temperature
ΘD.
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Kenji Watanabe, Yuh Fukai
1985 Volume 54 Issue 9 Pages
3415-3424
Published: September 15, 1985
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Calorimetric measurements have been made on vanadium hydride (and deuteride) to investigate the origin of excess specific heat due to H(D) atoms and the mechanism of phase transitions. The specific heat in the α phase was found to increase linearly with H(D) concentration at the rate of 2.0±0.1
kB/H atom and 2.4±0.1
kB/D atom at 240°C, nearly independent of temperature. The entropy changes on phase transitions,
ΔSβ1−β2 and
ΔSβ2−α, were measured as a function of hydrogen concentration, and the effect of alloying addition on these quantities was investigated.
ΔSβ1−β2 was found to be strongly affected by alloying, whereas
ΔSβ2−α was little affected. These results are at variance with the ordinary structure model, and suggest that H(D) atoms are in the 4T configuration in the α phase, and that a strong short-range order exists in the β
2 and α phases. From the effect of alloying on
ΔSβ1−β2, the number of sites blocked by one impurity atom (blocking number) is deduced.
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Masao Ogata, Yasushi Wada
1985 Volume 54 Issue 9 Pages
3425-3446
Published: September 15, 1985
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Viscosity of a kink in the one-dimensional φ
4 system is investigated. It is generated by momentum transfer between the kink and phonons. Mori’s formula for the viscosity is calculated in a form of low temperature expansion, using the collective coordinate method, in which the kink location is defined as a dynamical variable. Calculations up to the order of (
kBT)
2 are performed to find that the static limit of the viscosity is
(
Remark: Graphics omitted.),
where φ
0 is a displacement at which the φ
4 local potential is minimum,
m mass of an ion,
l lattice constant,
d width of the kink and ω
0 characteristic frequency of the phonons. Relation between the viscosity and diffusion constant is discussed and two mechanisms are pointed out for Brownian-like motion of the kink. In the sine-Gordon system, the viscosity of the soliton is shown to be zero up to the order of (
kBT)
2.
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Yasuhiro Seguchi, Mamoru Mekata
1985 Volume 54 Issue 9 Pages
3447-3453
Published: September 15, 1985
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The diffusion constants of impurities, Cd
++ and In
+++ ions as well as the mobile Ag
+ ions were measured in superionic α-Ag
2S, α-Ag
2Se and α-Ag
3SI with the α-AgI structure using tracers,
109Cd,
111In and
106mAg. Unexpectedly, high mobilities were observed also for the multivalent impurity ions. The obtained diffusion constants of the Ag
+ ions in α-Ag
2S and α-Ag
2Se are in good agreement with the reported values. It was concluded from the mobile ion dependence of activation energy for diffusion that in addition to the cation-anion and the electronic polarization, the repulsive and the cation-cation interaction play an important role in the interionic potential.
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Yasuhiro Seguchi, Mamoru Mekata
1985 Volume 54 Issue 9 Pages
3454-3462
Published: September 15, 1985
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The ionic motion in superionic conductors, Ag
2S, Ag
2Se and Ag
3SI was investigated by the γ-γ perturbed angular correlations (PAC) of
111Cd. Based on the jump diffusion model, the jump time of Ag
+ ions was deduced from the relaxation rate of PAC. The obtained jump time was found to be 2–150 ps and to increase in order of Ag
2S, Ag
2Se and Ag
3SI. The Arrhenius plot of the jump time gives almost the same activation energy as that for the diffusion constant. This indicates the flight path remains unchanged in the measured temperature range.
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Norimichi Kojyo
1985 Volume 54 Issue 9 Pages
3463-3471
Published: September 15, 1985
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An analytical and statistically homogeneous cluster theory for elementary excitations in disordered systems is developed on the basis of a graphical method in augmented space. An effective Hamiltonian diagram, preserving the original lattice symmetry and including all overlapping cluster scattering effects, is constructed. The expression for the averaged one-particle Green’s function, which corresponds to an interpolation formula connecting between weak and strong scattering and exhibits a momentum-dependent self-energy, is obtained from that diagram by introducing a Bethe lattice approximation. Calculations of the density of states and the spectral function for simple cubic lattices are presented, and show a better fit to exact numerical results than the single-site coherent potential approximation.
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Hiromi Noto
1985 Volume 54 Issue 9 Pages
3472-3477
Published: September 15, 1985
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The dependence of the charge-density waves on a propagation direction is investigated in a long-wavelength limit. It is shown that there exists a characteristic magnetic field
H0 at which electrons and holes oscillate with the non-magnetic plasma frequency \sqrtω
pe2+ω
ph2 for an arbitrary direction of propagation. This field is determined by electron and hole masses, carrier concentrations and a dielectric constant of the medium. For a perpendicular propagation to this field
H0, the highest frequency of the three collective modes is given by \sqrtω
ce2+ω
ch2 with out-of-phase oscillation of electrons and holes. The polarization property and the dispersion relation of the modes are investigated.
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R. P. Peters, Gerd Bergmann
1985 Volume 54 Issue 9 Pages
3478-3487
Published: September 15, 1985
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Magneto-resistance measurements on thin disordered films yield the phase-coherence time τ
i of the conduction electrons (weak localization). The dependence of τ
i on film thickness and residual resistivity are reported for disordered Au, Ag and Mg films in the temperature range between 4.5 and 20 K. The resistivity of the films was varied between .13 and 1.1×10
−6 Ωm. The temperature dependence of 1⁄τ
i follows a
Tp-law. The exponent is essentially two, but varies slightly with the resistivity. 1⁄τ
j depends much less on the resistivity than the linear prediction of the theory. No direct influence of the film thickness on τ
i was observed. This excludes the impurity induced Coulomb interaction as the relevant mechanism and suggests that τ
i is essentially determined by electron-phonon interaction. However, at the present time there is no theory available that reproduces the experimental results. Measurements of the (temperature independent) Hall-constant suggest that the thin films are rather homogeneous despite their small thickness.
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Hiroaki Hazama, Tetsuya Sugimasa, Tadashi Imachi, Chihiro Hamaguchi
1985 Volume 54 Issue 9 Pages
3488-3493
Published: September 15, 1985
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The first and the second derivatives of the transverse magnetoresistance are measured by the magnetic field modulation technique and are compared with each other. The results show that the second derivative is easily affected by the second harmonic component of the modulation magnetic field and that the peaks of the second derivative at high magnetic fields will not give accurate resonance positions. To avoid such effect and to measure the magnetophonon effect accurately, the first derivative method of the magnetoresistance is proposed for the magnetophonon measurements as the best method. It is also shown that the oscillatory component of the magnetophonon resonance can be obtained by numerical integration of the first derivative signals. The effective mass of the conduction band edge is estimated to be 0.0664±0.0005
m for n-GaAs at 160 K and 0.0135±0.0002
m for n-InSb at 77 K.
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Shuji Abe
1985 Volume 54 Issue 9 Pages
3494-3505
Published: September 15, 1985
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The impurity pinning of the charge density waves that exhibit three-dimensional order due to interchain coupling is investigated in the model of Fukuyama and Lee by taking account of phase distortions in the transverse directions as well as in the chain direction. Calculated adiabatic potentials elucidate the presence of metastable states, which is responsible for strong pinning and depinning. The linear response function calculated for the pinned state is in the form used for a dissipative harmonic oscillator and explains the overall feature of observed frequency dependent conductivities. Memory effects recently found in experiments are also qualitatively explained in the present model.
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Yoshiaki Kogure, Nobuyoshi Takeuchi, Yosio Hiki, Kaoru Mizuno, Takao K ...
1985 Volume 54 Issue 9 Pages
3506-3513
Published: September 15, 1985
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The attenuation of 10 MHz ultrasound in aluminum has been measured by the pulse reflection method at temperatures between 0.4 and 1.2 K. Three cylindrical single-crystal specimens of high purity and perfection, having 99.9999% of purity and low density of dislocations, were used and their crystallographic orientations were [100], [110] and [111]. The temperature dependence of attenuation in the superconducting state was analyzed on the basis of the BCS theory, and the apparent superconducting energy gap was determined for the above three sound propagation directions. By using these results, the energy gap anisotropy in the electronic
k-space was derived. The gap value ranged between 3.56 and 3.14 in units of (1/2)
kBTc. The gap was largest for the [100] direction, somewhat smaller for the [110] direction, and especially small for the [111] direction. These conclusions were in agreement with existing experimental and theoretical results.
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Takahito Kaneyoshi
1985 Volume 54 Issue 9 Pages
3514-3525
Published: September 15, 1985
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The specific heat for the amorphization of a crystalline Ising ferromagnet with a transverse field is investigated by the use of the effective-field theory with correlations. It is proposed that interesting phenomena of specific heat may be observable at low temperatures for the amorphization, although at the present time we do not have any experimental result.
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Kinshiro Hirakawa, Hiroaki Kadowaki, Koji Ubukoshi
1985 Volume 54 Issue 9 Pages
3526-3536
Published: September 15, 1985
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Real triangular lattice antiferromagnet with
S=1⁄2 has been long-awaited since Anderson pointed out that its ground state might be a quantum liquid-like state rather than the Néel state. In this paper we report that NaTiO
2 and LiNiO
2 are promising candidates for it, the former being near Heisenberg-type and the latter near Ising-type. Our magnetization measurements on LiNiO
2 show a striking linear to nonlinear response transition at
TN1=210 K. A pronounced anomaly appears in ESR at another transition
TN2=∼20 K suggesting a ferrimagnet-like ordered state below. However, neither ferromagnetic nor antiferromagnetic reflections could be observed in zero field neutron scattering between 1.4 and 300 K. The susceptibility of NaTiO
2 is low suggesting a strong antiferromagnetic coupling between the spins but no Brass scattering could be observed at 1.4 K. These are suggestive of the remarkable quantum effects.
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Hisazumi Akai, Junjiro Kanamori
1985 Volume 54 Issue 9 Pages
3537-3542
Published: September 15, 1985
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Antiferromagnetic susceptibilities of Cr
1−xM
x (M=Al, Be, Ge) are calculated in the framework of KKR–CPA. It is shown that the antiferromagnetic susceptibility is strongly enhanced with increasing
x, whereas the so-called nesting anomaly is effectively suppressed by the alloying. These results are quite consistent with a magnetic phase diagram seen in the CrAl system.
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Hirofumi Wada, Kazuyoshi Yoshimura, Masayuki Shiga, Tsuneaki Goto, Yoj ...
1985 Volume 54 Issue 9 Pages
3543-3547
Published: September 15, 1985
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The high field magnetization of RMn
2, where R stands for a rare-earth element, has been measured at 4.2 K by using pulsed magnetic fields up to about 300 kOe. The magnetizations of YMn
2, PrMn
2, NdMn
2 and SmMn
2 increase almost linearly with increasing magnetic field. The magnetization curves of GdMn
2, TbMn
2, DyMn
2, HoMn
2 and BrMn
2 show a trend of saturation at high fields. The saturation magnetic moments per formula unit were estimated as 6.2 μ
B, 9.5 μ
B, 10.0 μ
B, 10.3 μ
B, 10.1 μ
B and 8.9 μ
B for GdMn
2, TbMn
2, DyMn
2, HoMn
2(C15), HoMn
2(C14) and ErMn
2, respectively. These values are in agreement with the R
3+ moments except for GdMn
2. The analysis on GdMn
2 excludes particularly a simple ferrimagnetic coupling between Gd and Mn moments.
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Makio Kurisu, Hiroshi Tanaka, Hideoki Kadomatsu, Kazuko Sekizawa, Hiro ...
1985 Volume 54 Issue 9 Pages
3548-3553
Published: September 15, 1985
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The electrical resistivity, ac magnetic susceptibility and magnetization of CeTl were measured at pressures up to 17 kbar. At ambient pressure the cubic to tetragonal transition occurs at
TM=193 K and antiferromagnetic state with a metamagnetic character below the Néel temperature
TN=25.5 K. When pressure
p increases,
TM increases at a rate of d
TM⁄d
p=+19 K/kbar,
TN decreases at a rate of d
TN⁄d
p=−0.28 K/kbar and metamagnetic transition field
Hc at 4.2 K decreases from 20 kOe at ambient pressure. Above about 10 kbar, pressure-induced ferromagnetic phase appears and its Curie temperature
Tc increases at a rate of d
Tc⁄d
p=+0.10 K/kbar.
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