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Tohru Yoneyama
1985 Volume 54 Issue 2 Pages
451-453
Published: February 15, 1985
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It is shown that the solutions of three kinds of the interacting soliton equations can be expressed
explicitly by the squared eigenfunctions of the corresponding two-component equations which appear in the inverse method. The interacting soliton equations is a system of coupled nonlinear differential equations obtained by an interacting soliton picture, and is an extension or a decoupling of the original nonlinear equation with soliton solution. The Korteweg-de Vries (KdV), the sine-Gordon and the modified KdV cases are shown.
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Yukiharu Ohsawa, John M. Dawson
1985 Volume 54 Issue 2 Pages
454-457
Published: February 15, 1985
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A 2-1/2 dimensional relativistic, electromagnetic particle code is used to study the stability of Elmo Bumpy Torus. In the simulation, the plasma is much more stable to the high-frequency hot electron interchange mode than theoretical predictions. One possible explanation is wave damping by flattening of hot electron density along the poloidal direction due to the spread of the drift velocity.
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Shobu Kaneko, Atsushi Kamitani
1985 Volume 54 Issue 2 Pages
458-461
Published: February 15, 1985
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A method for automatic numerical generation of a body-fitted curvilinear coordinate system is applied to the determination of the magnetohydrodynamic equilibrium configuration. The region of a complex shape in the physical plane is mapped onto a square region and the Grad-Shafranov equation is solved in this square region with a rectangular mesh. Several results for the equilibrium configurations of the spheromak plasmas in flux conservers are shown as examples. As the flux conservers, the oblate spheroid and the drum type are considered.
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Hideyuki Sato, Kiyoshi Yonemitsu, Yoshichika Onuki, Takemi Komatsubara
1985 Volume 54 Issue 2 Pages
462-465
Published: February 15, 1985
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The current-voltage characteristics on point contacts of a new Kondo lattice compound CeCu
6 were investigated experimentally at liquid helium temperatures. The spectra of CeCu
6 were decomposed into symmetric and asymmetric parts, and were compared with those of the reference compound LaCu
6. The asymmetric part shows a sharp step near 2 to 2.5 mV bias voltage, while the symmetric part shows a logarithmic dependence on bias voltage near 10 mV.
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Hiroyuki Nagai, Isamu Oguro
1985 Volume 54 Issue 2 Pages
466-469
Published: February 15, 1985
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The magnetic properties of the pseudo-binary compounds Dy(Fe
1−xMn
x)
2 have been investigated. The Dy moments cant at the angle of 35° from the easy axis of DyMn
2. The
x-dependence of the saturation moment is explained by the antiferromagnetic coupling of Mn moment pair. The paramagnetic Curie temperatures decrease as
x increases, while the effective magnetic moments increase. The hysteresis curves of magnetizations for 0.2≤
x≤0.8 were observed.
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Tadashi Shimizu, Masashi Takigawa, Hiroshi Yasuoka, Yoshichika \={O}nu ...
1985 Volume 54 Issue 2 Pages
470-473
Published: February 15, 1985
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63Cu nuclear spin-lattice relaxation rate (1⁄
T1) has been measured in a dense Kondo compound CeCu
6. The nuclear relaxation was not expressed by a single exponential time dependence probably because of the many inequivalent Cu sites and/or the anisotropy in 1⁄
T1. The relaxation rate of the Ce magnetic moments (1⁄τ) deduced from the largest value of 1⁄
T1 showed the similar temperature dependence as those in CeAl
3 and CeCu
2Si
2 obtained from the neutron scattering experiments, but much larger value than these compounds, although considerable ambiguity is present in the estimation of the absolute value of 1⁄τ.
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Nobuhiko Sakai, Hisashi Sekizawa
1985 Volume 54 Issue 2 Pages
474-476
Published: February 15, 1985
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A Mössbauer spectrum is measured on Fe metal with a new resonance technique which utilizes magnetically modulated hyperfine-split energy levels of
57Fe nuclei in a paramagnetic Pd metal source. A slowly varying external magnetic field up to 22 kOe was applied on a
Pd57Co source cooled to 4.2 K. Advantages of this method coming from elimination of Doppler modulation are pointed out.
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Syuji Kawada, Hisao Dohata
1985 Volume 54 Issue 2 Pages
477-479
Published: February 15, 1985
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The temperature dependence of the dielectric dispersion of KOH-doped ice was measured at the temperature range from 55 K to 90 K at frequencies 0.002 Hz∼1 Hz. The phase transition at 72 K was clearly observed only at the heating stage from the temperature dependence of the dielectric constant and the relaxation time. The observed low temperature phase should be a non-equilibrium state on the way of protonic ordering in the ice crystal.
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Etsuro Sawaguchi, Yukikuni Akishige, Masakazu Kobayashi
1985 Volume 54 Issue 2 Pages
480-482
Published: February 15, 1985
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Distinct dielectric anomalies have been found in the hexagonal modification of BaTiO
3 at 60 K and 222 K. X-ray studies have revealed that a structural distortion from the prototypic hexagonal structure occurs at
T0=222 K. Below
T0, a very weak diffraction line has been detected, which is the forbidden line for the hexagonal space group of P6
3/mmc; and the diffraction intensity
I in the new phase is given approximately by
I∝
T0−
T. The transition at 222 K is very probably of the second order. A possibility is speculated that a ferroic transition takes place below
T0.
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Hiroshi Tanino, Naoki Koshizuka, Koichi Kobayashi, Masahiro Yamashita, ...
1985 Volume 54 Issue 2 Pages
483-486
Published: February 15, 1985
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Absorption, luminescence and Raman spectra are studied under high pressure in Wolffram’s red salt. It is suggested that the quasi-one-dimensional electron-phonon system is continuously changed by pressure from a moderate coupling state at atmospheric pressure to a weak coupling state, not by decreasing the electron-phonon coupling energy, but by increasing the transfer energy. The decrease of the phonon energy of the symmetric stretching vibration of Cl around Pt
IV and the rapid decrease of the energy gap with the pressure increase up to 0.2 GPa are thought because the Pt
IV–Cl distance would increase with increasing pressure as the Pt
IV–Pt
II distance decreases.
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Masato Yoshimori
1985 Volume 54 Issue 2 Pages
487-489
Published: February 15, 1985
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The Hinotori satellite observed eight solar gamma-ray line flares between April, 1981 and June, 1982. Ratios of the fluence of 2.22 MeV gamma-ray line resulting from neutron capture on proton to the fluence of 4.44 MeV gamma-ray line resulting from the nuclear deexcitation of C are shown as a function of the heliolongitude of flare. The ratios are roughly constant for disk flares, but decreased for limb flares. The present result suggests that the particle acceleration produces energy spectra that do not vary much from flare to flare. The limb darkening of the ratios can be interpreted in terms of the attenuation of the 2.22 MeV gamma-ray line by Compton scattering in the photosphere.
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Akira Nakamura, Ryogo Hirota
1985 Volume 54 Issue 2 Pages
491-499
Published: February 15, 1985
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We have found a new example of the 1+1 dimensional explode-decay solitary waves. The equation is the classical Boussinesq equation written as
ut=((1+
u)
v−
vxx)
x,
vt=(
u+(1⁄2)
v2)
x where subscripts represent partial derivatives. The explode-decay solitary wave solutions are expressed by the Hermite polynomials. Bäcklund transform and the inverse scattering transform scheme have been obtained. We have shown that the present solutions are related to the rational solutions of the nonlinear Schrödinger equation
iψ
t+ψ
xx−2ψ
*ψψ=0.
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Kin’ya Takahashi, Atsushi Ichimura, Hajime Hirooka, Nobuhiko Sai ...
1985 Volume 54 Issue 2 Pages
500-515
Published: February 15, 1985
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The response of the regular and irregular regions to a periodic external force in two-dimensional Hamiltonian systems are studied, through power spectrum, energy change, Poincaré map and Lyapunov number. In the regular case, three-dimensional tori are constructed for small perturbation. It is shown that there exists a certain critical value
ac of the amplitude of the external force below which the trajectories are regular but above which they become irregular. In the irregular region, main attention is paid to the Lyapunov number, which is shown to vary sensitively to the variation of the amplitude, indicating the difference of the nature of the orbits. This suggests that perturbation theory is not applicable to the irregular case, as is usually done in the linear response theory.
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Harukazu Igarashi
1985 Volume 54 Issue 2 Pages
516-528
Published: February 15, 1985
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An improved Padé method is applied to the entropy and the reduced susceptibility χ
R (=χ·
kBT⁄
N(
gμ)
2) expanded in powers of the internal energy in order to calculate the specific heat
c(
T) for
S≤2 and the zero-field susceptibility for
S=1⁄2 of a quantum Heisenberg spin chain, respectively. The exponents α (
c(
T)∼
Tα) obtained for an antiferromagnetic exchange and 1≤
S≤2 are 1.6, 1.4 and 1.3, which are much different from the value (α=1) given by the spin-wave theory (SW). It is also shown that the polynomials with exponents given by SW cannot fit in with the Padé approximants for these cases. This disagreement with the behaviors of SW is ascribed, at least for
S=1, to the nonzero gap found by Botet and Jullien.
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Seibun Yamashita
1985 Volume 54 Issue 2 Pages
529-543
Published: February 15, 1985
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Detailed experimental information is given for five families of the highest energy range,
ΣEγ>1000 TeV. They are named Andromeda, Ursa Maior, M.A.I, M.A.II and M.A.III. Among them, Andromeda, Ursa Maior and M.A.III are observed by a chamber of large thickness and their information both on the electromagnetic and hadronic component is available. All the observed three events are hadron-rich and the energy spectrum of hadrons is harder than that of electrons/gamma-rays. The data is found inconsistent with the hypothesis of proton primary with pion multiple production under the scaling model, after comparison with simulation calculation.
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Ichiro Kawakami, Masamitsu Aizawa, Katsumi Harada, Hiroyuki Saito
1985 Volume 54 Issue 2 Pages
544-554
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A numerical method is proposed to solve a hyperbolic system of nonlinear partial differential equations of conservation laws. The method is formulated as a finite element method (FEM), but the finite elements and the nodes move with arbitrary velocity (ALE). This method is called FEMALE. It is shown that the velocity of nodes should be identified with the local velocity of the nonlinear waves such as the shock wave, the contact discontinuity and the rarefaction wave, then numerical accuracy is much improved. A numerical method is also presented to obtain the local velocity of the nonlinear waves.
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Hiroki Yoshihara
1985 Volume 54 Issue 2 Pages
555-565
Published: February 15, 1985
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A stochastic broadening of plane shock front due to small-amplitude waves of random phase is considered. It is given by the root mean square of displacement of the shock front, which is replaced by a sharp discontinuity in the limit of infinitly small dissipation. It was found that at a large time the broadening is proportional to
t1⁄2, and mainly the spectrum of intensity of noise near ω=0 contributes to the broadening.
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Toshihiko Dote, Masatoshi Shimada
1985 Volume 54 Issue 2 Pages
566-571
Published: February 15, 1985
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An early problem of the transition from free to ambipolar diffusion of electrons has been reexamined. Starting from the classical flow equations for electrons and positive ions and the continuity equations for charged particles, we have obtained a general characteristic equation of effective diffusion coefficient for electrons, where the results due to Allis have been corrected. The transition characteristics calculated from the above general equation have been extremely concrete and practical. Finally this approach has been applied to the cylindrical positive column of glow discharge and an example of the characteristics has been presented as a function of the plasma density for various values of the electron temperature.
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Masayoshi Tajiri, Katsunobu Nishihara
1985 Volume 54 Issue 2 Pages
572-578
Published: February 15, 1985
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A modified Korteweg-de Vries equation with nonlocal term due to the Landau damping effect is shown to govern a nonlinear ion acoustic wave even with relatively large amplitude in a two-electron-temperature plasma where uniform states are characterized with the parameters near the boundary between the normal and the anomalous propagation property region.
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Hiroshi Shirai, Masahiro Wakatani, Hideki Zushi, Yousuke Nakashima, Os ...
1985 Volume 54 Issue 2 Pages
579-590
Published: February 15, 1985
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Nonlinear evolution of tearing instability with a poloidal mode number
m=1 and a toroidal mode number
n=0 is studied in a straight helical system with an i=0 surface, where i denotes a rotational transform. On the basis of a low beta resistive MHD model derived by using the stellarator expansion, it is shown that the
m=1⁄
n=0 magnetic island grows to cover the whole central region; then, plasma current is readjusted and it almost recovers the initial profile. The large magnetic island causes outflow of ions, since the level of poloidal field fluctuations reaches about 10%. This whole process seems to repeat and may explain relaxation oscillations of ion temperature detected by neutral particle analyzer in the Heliotron E experiment.
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Yukiharu Tagawa, Junji Sakurai, Yukitomo Komura, Hirofumi Wada, Masayu ...
1985 Volume 54 Issue 2 Pages
591-597
Published: February 15, 1985
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Powder X-ray diffraction measurements on intermetallic compounds RMn
2 (R: Y, Pr, Nd, Sm and Gd) have been made in a temperature range from 69 to 300 K. Below
TN, every sample shows a large volume expansion, being as large as 4.6% for YMn
2. In addition, PrMn
2 and NdMn
2 having the hexagonal C14 type of crystal structure are distorted into monoclinic below
TN. On the other hand, SmMn
2 having the same C14 type structure is distorted into orthorhombic. On the basis of a theory of magnetoelastic coupling the directions of magnetization of these compounds below
TN were determined. The cubic C15 type YMn
2 shows a very small and probably rhombohedral distortion below
TN, whereas the same C15 type GdMn
2 shows no symmetry change.
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Kinichi Masuda, Hirofumi Ushio, Kenichi Kojima
1985 Volume 54 Issue 2 Pages
598-603
Published: February 15, 1985
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A tight-binding type electronic theory (molecular approximation) is used to calculate the formation energy of the double kink
Edk for a 1⁄2[110](1\bar11) (perfect glide set) screw dislocation in covalent semiconductor Si. Effects of external shear stress on the double kink nucleation process are investigated in detail. It is shown that the calculated stress dependence of the
Edk is in good agreement with the experimental results of the activation energy for the screw dislocation motion in Si.
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Hiroaki Kamioka, Yoshio Sumino
1985 Volume 54 Issue 2 Pages
604-607
Published: February 15, 1985
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The attenuation of ultrasonic wave in sodium has been measured by the pulse transmission method in the temperature range from 20 to 160°C through the melting temperature of 97.8°C. The frequency of sound used was 1 MHz. The typical value of attenuation in solid phase was 0.279 neper/cm, and that in liquid phase was 0.201 neper/cm. At the melting point, a large absorption of ultrasonic wave was seen and its value amounted to 0.51 neper/cm in the melting process and 1.21 neper/cm in the solidification process. The increase of the attenuation at the melting point may be due to the Rayleigh scattering, which is appreciable in the mixed state of the liquid and the suspending crystallites. By combining the present results with our previous data on sound velocity, discussion was made on the variation of elastic and anelastic properties of sodium during its melting and solidification processes.
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Masayoshi Yamada, Yoshiaki Yamasaki, Yasuaki Honma, Keiichi Yamamoto, ...
1985 Volume 54 Issue 2 Pages
608-612
Published: February 15, 1985
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Brillouin scattering measurements have been made to determine a complete set of elastic tensor components in GaSe
1−xS
x (0≤
x≤1) layered crystals. It is found that most elastic tensor components exhibit discontinuities at the compositions
x≈0 and/or
x≈0.4, associating with the ε-γ and γ-β polytype transformations. With a simple layered structure model, the diagonal components of the elastic tensor are related to the inter- and intra-layer force constants. The composition and polytype dependences of the compressive and shear interlayer force constants are discussed by taking account of the Van der Waals interactions and the Coulomb interactions between two atoms in adjacent layers.
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S. K. Kor, A. K. Srivastava
1985 Volume 54 Issue 2 Pages
613-616
Published: February 15, 1985
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The paper reports experimental results of ultrasonic absorption and velocity in a liquid crystalline mixture of ocatadecanol and cholestrol with different concentrations and its behaviour with temperature specially near transition temperature. The absorption has been measured using the pulse technique and the velocity with the help of an acoustic interferometer both at a single frequency of 2 MHz. The temperature has been controlled to within ±0.2°C. Abrupt increase in absorption and decrease in velocity has been observed near cholesteric-isotropic transition temperature and the results have been discussed qualitatively.
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R. K. Ram, S. S. Kushwaha
1985 Volume 54 Issue 2 Pages
617-624
Published: February 15, 1985
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Phonon dispersion relations for compounds having zinc blende structure have been studied in the framework of dynamic model, which takes into account the covalent nature of atomic bonds. The calculated dispersion curves for GaAs and InSb along three symmetry directions [100], [110] and [111] in K-space are found to be in good agreement with the measured inelastic neutron scattering data.
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Masahide Matsuura, Haruhiko Yao, Kazutoshi Gouhara, Ichiro Hatta, Nori ...
1985 Volume 54 Issue 2 Pages
625-629
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The heat capacity (
Cp) of quartz was measured by AC calorimetry near the α-β phase transition temperature. The existence of the intermediate phase (IP) was confirmed. A sharp increase of
Cp was observed at
TC, the lower transition temperature. The value of
TC in heating runs (HR) was higher than that in cooling runs (CR) by about 0.9 K. A hump of
Cp was clearly observed at
TQ, the higher transition temperature in CR and also in HR of a special heating cycle without passing through
TC. It was obscure, however, in the ordinary HR because of the hysteresis. The temperature range of IP was 1.15±0.05 K in CR, which is significantly narrower than the range where the X-ray satellite reflections are observable.
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Katsuhiko Suzuki, Yoshika Masuda
1985 Volume 54 Issue 2 Pages
630-638
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Thermal expansion in the itinerant electron magnetic Ni
3Al system has been measured at temperatures 4.2 K≤
T≤60 K. In the ferromagnetic samples (74.6, 75.0 and 75.2 at%Ni) in this system, a linear thermal expansion coefficient α shows a jump at the respective
Tc, and the behavior of α in the temperature region near the respective
Tc is well explained by the self-consistent renormalization (SCR) theory of spin fluctuations by Moriya and Usami. In the paramagnetic sample (74.0 at%Ni) the behavior of α is also explained by this theory very well. Moreover the inverse magnetic susceptibility, χ
−1 in the paramagnet shows the
T4⁄3-dependence in the region of high temperatures
T≥13 K and the
T2-dependence below about 13 K. In the ferromagnets χ
−1 shows the
T4⁄3-dependence above the respective
Tc. These facts agree with the prediction by the SCR theory of spin fluctuations.
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Shin-ya Miyatani
1985 Volume 54 Issue 2 Pages
639-649
Published: February 15, 1985
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Following Part I, the chemical diffusion in ionic-electronic mixed conductors under various driving forces and boundary conditions is investigated both theoretically and experimentally. Our subjects are now (1) chemical drift, (2) ac characteristics, (3) thermal diffusion, (4) two-dimensional diffusion and (5) chemical diffusion at applying a magnetic field. The exeriments on silver chalcogenides show good agreement with theory.
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Yositaka Yosida, Sei-ichi Tanuma
1985 Volume 54 Issue 2 Pages
650-652
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Induced torque of the second stage SbCl
5-graphite intercalation compounds (GIC’s) has been studied in magnetic field up to 20 kOe. Field dependence of induced torque at the field direction parallel to the layer plane gives an evidence of open orbit along the
kz-axis which is suggested by the de Haas-van Alphen (dHvA) effect. Reduction of the induced torque has been observed when the sample is slowly cooled down to a quenching temperature, about 210 K, and then quickly cooled down to 4.2 K. These results are consistent with the reduction of the amplitude of dHvA oscillations which was found by the present authors.
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Atsuko Sumi, Hitoshi Sumi
1985 Volume 54 Issue 2 Pages
653-665
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Exciton polarons dressed with a cloud made of several phonons exist as a new phase in the f.c.c. lattice between the phase of self-trapped excitons dressed with much more phonons and that of free excitons essentially undressed. The exciton polaron in the new phase moves slowly resonating among localized polaron states whose phonon cloud has a symmetry of two-center type centered at each pair of nearest-neighbor sites. This phase cannot be obtained in the s.c. lattice where a pair of nearest neighbors have no common nearest neighbors. The exciton-phonon interaction modifying the transfer integral of exciton must have an intermediate strength in order for this phase to be realized. It can be ascribed to this phase that in a mixed crystal of AgBr
1−xCl
x where silver or halogen ions constitute the f.c.c. sublattice phonon replicas in the luminescence spectrum peak at a line of the severalth order for
x∼0.45 just before the self-trapped state is stabilized.
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Yutaka Maniwa, Kiyoshi Kume, Hiroyoshi Suematsu, Sei-ichi Tanuma
1985 Volume 54 Issue 2 Pages
666-676
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High resolution
13C NMR has been observed in highly oriented crystals of pristine graphite and K-GIC’s. The NMR spectrum consists of several well resolved lines which can be assigned to the interior and bounding carbon layers. The
13C spin-lattice relaxation time
T1 shows the metallic characteristics,
T1T=constant between about 1.5 K and R.T. From
T1 of each resolved absorption line, the c-axis charge distribution was quantitatively determined for stage 3 and 6, which is strongly inhomogeneous. The obtained distribution was also supported by an analysis of the frequency shift of
13C NMR. In stage 1 it was suggested, from a comparison of
T1 with electronic specific heat, that the conduction electrons near the Fermi level spread over not only graphite layers but also interlayer space containing K-atoms.
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Akira Hasegawa
1985 Volume 54 Issue 2 Pages
677-684
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The de Haas-van Alphen effect of the semimetallic lanthanum pnictides LaSb and LaBi, which have attracted interest as a proper reference material for a study of anomalous physical properties observed in the Ce pnictides, is explained by the Fermi surface which is calculated by a relativistic APW method with the local-density approximation. The Fermi surface of both pnictides consists of two small hole sheets centred at
Γ and three equivalent electron pockets centred at X. Calculated extremal cross-sectional area and cyclotron mass agree reasonably well with experimental results.
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Norio Kawakami, Ayao Okiji
1985 Volume 54 Issue 2 Pages
685-691
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The equilibrium thermodynamic equations for the highly correlated degenerate Anderson model are obtained on the basis of the Bethe-Ansatz method, in the presence of the magnetic field and the crystal field. These equations are treated analytically at low temperatures and the general expression for the specific heat is obtained, which shows the Fermi-liquid properties. As a simple example, the present theory is applied to the case of the Ce impurities in a cubic crystal field. The present formalism is also applicable to the case where the spin-orbit coupling exists.
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Shoichi Mase, Takeshi Fukami, Thanh Xuan Do, Masatoshi Mori
1985 Volume 54 Issue 2 Pages
692-700
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The occurrence of a peak at a characteristic temperature
T0 in the plot of the sound attenuation coefficient α(
T,
f,
Hp) against the temperature
T was reinvestigated in detail. Here
Hp is a certain specified peak position of α(
T,
f,
H) versus
H curve. Main experimental results are as follows. (i)
T0 appears only in the case of simultaneous absorption of phonons due to electrons and holes. (ii) The 3/4 Width
ΔH3⁄4 of α(
T,
f,
H) versus
H curve for the overlapped peaks shows a minimum at
T∼
T0 as a function of
T. (iii) In the neighborhood of
T∼
T0, the attenuation curve becomes of a cusp-shape in the very neighborhood of
H∼
Hp. It is pointed out that any existing theories of the magnetoacoustic attenuation in normal semimetals can not at all explain the above experimental results.
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Yositaka Yosida, Sei-ichi Tanuma
1985 Volume 54 Issue 2 Pages
701-706
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The effect of cooling rate on the de Haas-van Alphen (dHvA) oscillation and on the in-plane structure has been studied by the use of electron diffraction in the second stage SbCl
5-graphite intercalation compounds (GIC’s). When the cooling rate through the phase transition temperature, 210 K, is fast, a large volume of the regular spot pattern of (\sqrt7×\sqrt7)R19° and (\sqrt39×\sqrt39)R16° corresponding to the higher temperature phase remains, while non-negligible volume of the diffuse diffraction pattern of the intercalant corresponding to the low temperature phase appears. Compared with the case of the slow cooling through 210 K, the amplitudes of the dHvA oscillation were found to increase without changing their frequencies. Even in the case of slowest cooling, the crystal-line phase pattern remained definitely. These facts have removed such an apparent controversy that the glassy phase of the material at low temperature should yield many kinds of dHvA oscillation frequencies.
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Yositaka Yosida, Sei-ichi Tanuma
1985 Volume 54 Issue 2 Pages
707-712
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The de Haas-van Alphen (dHvA) effect in the second stage SbCI
5-graphite intercalation compounds (GIC’s) has been studied. Ten dHvA frequencies are observed. Most of dHvA frequencies are fitted to the cylindrical Fermi surface (FS) model. Deviation from the cylindrical FS model has been observed for one of the three main oscillation branches. For this branch δ an undulated shape with a hyperboloidal part is fairly fitted. This result suggests that the interaction must be taken into account between graphite layers bounding the intercalant layers: the interaction has not been considered so far in the previous band calculations. The amplitude reduction of the dHvA oscillation at high fields has been observed for the branch δ. This behavior is interpreted in terms of the phase-smearing produced by the spatial variation of the strain.
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Yoji Koike, Seizo Morita, Takashi Nakanomyo, Tetsuo Fukase
1985 Volume 54 Issue 2 Pages
713-724
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Conductivity and magnetoconductivity have been measured for various kinds of graphite crystals at low temperatures down to 0.03 K. Anomalous behaviours have been found in polycrystalline (but well oriented) specimens of graphite. At low temperatures below 0.1 K, the conductivity shows
T1⁄2 dependence in and without magnetic field, Anisotropic magnetoconductivity is observed. It varies as
H1⁄2, with the sign which changes from negative to positive with increasing magnetic field strength. These behaviors are fairly well explained in terms of localization and electron-electron interaction in the three-dimensional weakly localized regime. The inelastic scattering time τ
ε shows a little weaker temperature dependence than
T−1.
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Takashi Nakashima, Chihiro Hamaguchi, Junji Komeno, Masashi Ozeki
1985 Volume 54 Issue 2 Pages
725-735
Published: February 15, 1985
Released on J-STAGE: June 01, 2007
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Magnetophonon effect has been studied in the transverse magnetoresistance of high purity epitaxial n-InP at temperatures between 77 and 300 K, by adopting the magnetic field modulation and phase sensitive second harmonic detection technique. Up to the 10th extrema are resolved at 88 K. The band edge effective mass is estimated to be 0.0813±0.001 m at 80 K and 0.0763±0.001 m at 282 K. The temperature dependence of the effective mass is discussed by the
k·
p perturbation theory and squared momentum matrix element is determined to be
Ep=16.6 [eV]. The energy bands of InP throughout the entire Brillouin zone has been calculated by diagonalizing a modified
k·
p Hamiltonian referred to 30 basis states at
k=0 and a reasonable agreement with the present data is obtained.
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Ichiya Sadakata
1985 Volume 54 Issue 2 Pages
736-739
Published: February 15, 1985
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Theories of the conductivity in weakly disordered systems are extended to be applicable to strongly disordered systems. Effects of the strong disorder are taken into account within the coherent potential approximation. The conductivity of three dimensional systems is discussed.
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Ken-ichi Fujii, Tyuzi Ohyama, Eizo Otsuka
1985 Volume 54 Issue 2 Pages
740-751
Published: February 15, 1985
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Cyclotron resonance measurement of electrons coexisting with a large electron-hole drop in germanium was performed using 35 GHz microwaves. Absorption peaks of electrons belonging to two different valleys were observed, so all the free electrons do not populate a single valley in the same manner of carriers in the large electron-hole drop and excitons surrounding the drop in a strain well. It is found that the energy difference between strain-induced up- and down-valleys becomes 0.5 meV at 3 K. This value is considarably smaller than that estimated by using the result of previous calculations related to the large electron-hole drop. The reason is explained by means of a space charge caused by free carriers coexisting with the large electron-hole drop. Numerical calculation considering space charge gives 0.8 meV for the energy difference at 3 K.
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Yoshiko H. Ohashi, Kazutoshi Ohashi, Mitsuru Terada, Yujiro Ohba
1985 Volume 54 Issue 2 Pages
752-761
Published: February 15, 1985
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We have measured the current-voltage characteristics of β-Ag
2S layer at the liquid-nitrogen temperature. Samples showed that there is the non-linear evoluation of the electrical current. Our experimental results are consistent with Bishop’s theory treating the interacting Brownian particles in a periodic local potential.
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Kazushige Kawabata
1985 Volume 54 Issue 2 Pages
762-770
Published: February 15, 1985
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The superconducting transition temperature
Tc and the sizes of the resistive anomalies due to both the
q1- and the
q2-CDW formations are examined on single crystals of Ta-doped NbSe
3. With addition of Ta,
Tc increases steeply from below 70 mK to 1.7 K but turns to decrease at 5 at%Ta. The sizes of the resistive anomalies due to both CDW formations initially decrease but that due to the
q1-CDW begins to increase at 5 at% where
Tc turns to decrease. These results are discussed in terms of the competition between superconductivity and the CDW formations. The upper critical field is also measured in the superconducting state induced by Ta doping. The critical field shows one-dimensional anisotropy, which originates from the anisotropy of the electronic band structure.
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Nobuyuki Momozawa, Yasuo Yamaguchi, Humihiko Takei, Masaru Mita
1985 Volume 54 Issue 2 Pages
771-780
Published: February 15, 1985
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Neutron and X-ray diffraction studies and magnetization measurements were carried out on single crystals of (Ba
1−xSr
x)
2Zn
2Fe
12O
22. The substitution of Ba by Sr produces two effects on the crystal structure: a lattice deformation around the Sr ions and a redistribution of the Zn and Fe ions in the tetrahedral sites. The magnetic structure is analyzed in consideration of these effects: Spins are bunched in the form of ferrimagnet in the every (T
1⁄2ST
1⁄2) block and the bunched spins make an angle φ
0 between the adjacent (T
1⁄2ST
1⁄2) blocks. At 294 K, the turn angles φ
0’s are found to be 0° (ferromagnetic), 0°<φ
0<180° (helical) and 180° (antiferromagnetic) for 0≤
x≤0.5, 0.5<
x<0.8 and 0.8\lesssim
x≤1.0, respectively. A brief discussion on the exchange interaction of this spin system is given.
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Masatoshi Arai, Yoshikazu Ishikawa, Norio Saito, Humihiko Takei
1985 Volume 54 Issue 2 Pages
781-794
Published: February 15, 1985
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The spin correlations in a cluster type spin glass of 90FeTiO
3-10Fe
2O
3 have been studied by neutron small and high angle scattering from a single crystal. The magnetic correlations of the moments parallel and perpendicular to the c axis, 〈
Sq||S-q||〉 and 〈
Sq⊥S-q⊥〉 have been separately determined and the spin configuration inside the cluster as well as the cluster configuration have been determined. The spin glass transition temperature has been found to correspond to the temperature where the spin axis inside the cluster aligns in the c axis and the antiferromagnetic modulation starts to occur inside the cluster.
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Masatoshi Arai, Yoshikazu Ishikawa
1985 Volume 54 Issue 2 Pages
795-802
Published: February 15, 1985
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The magnetization process in a cluster type spin glass of 90FeTiO
3-10Fe
2O
3 has been studied by neutron small and large angle scattering in a magnetic field up to 5 kOe. The magnetization process along the c axis at 12 K can be understood as the successive irreversible rotation of the magnetic moment in clusters with different sizes. The smaller clusters have the higher coercive force and remain unchanged for a field weaker than the coercive force. The modulated spin structure established below Tg does not vary at 12 K in this magnetization process.
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Takashi Iwashita, Norikiyo Uryû
1985 Volume 54 Issue 2 Pages
803-811
Published: February 15, 1985
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For the anisotropic Heisenberg ferromagnet with mixed spins of
S=1⁄2 and
S=1, the Curie temperature
Tc has been calculated with the use of pair model approximation. Assuming the anisotropic bilinear and biquadratic exchange interactions (
J and
J′) between nearest neighbors of the different spins, and the uniaxial single-ionic anisotropy
D for each spin of
S=1, the behaviors of
Tc as a function of these exchange parameters and the uniaxial anisotropy parameter are investigated for some types of the spin system with various values of the anisotropy parameter α of the exchange interaction. For small values of the exchange anisotropy parameter α it has turned out that
Tc decreases with
D in the range of 0≤
D≤0.5
J1. Furthermore, the biquadratic exchange interaction turns out to give little effect on the Curie temperature of the anisotropic Heisenberg ferromagnet with mixed spins when the exchange anisotropy parameters are in the range of 0.48≤α≤0.55.
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Shuichi Hayase, Takafusa Futamura, Hirofumi Sakashita, Hikaru Terauchi
1985 Volume 54 Issue 2 Pages
812-817
Published: February 15, 1985
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The measurement of the diffuse X-ray scattering in a random mixture of ferroelectric RbH
2PO
4 (RDP) and antiferroelectric NH
4H
2PO
4 (ADP), (RDP)
1−x(ADP)
x, has been carefully carried out. The equi-intensity contours of the diffuse scattering observed in glassy (RDP)
0.3(ADP)
0.7 is similar to that in antiferroelectric (RDP)
0.15(ADP)
0.85 near the Neel temperature, implying that there are small antiferroelectric clusters in the glassy phase of the antiferroelectric side. But the temperature dependence of the scattering intensity in the glassy phase is distinctly different from that in the antiferroelectric phase.
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Alexander A. Volkov, Gennadi V. Kozlov, Yuri G. Goncharov, Mitsuo Wada ...
1985 Volume 54 Issue 2 Pages
818-821
Published: February 15, 1985
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The dielectric dispersion associated with the ferroelectric phase transition in Li
2Ge
7O
15 has been measured in the paraelectric phase by means of a backward-wave oscillator spectrometer in the frequency region 8–24 cm
−1. A temperature dependent resonant mode was found, which corresponds to the soft mode previously observed in the ferroelectric phase by Raman scattering. This mode has a very small oscillator strength and its contribution to the dielectric constant does not exceed 0.1 even in the vicinity of the transition point. A relaxational mode with the characteristic frequency of about 0.03 cm
−1 is required for consistently explaining the reported dielectric anomaly.
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Hiroyuki Mashiyama, H. -G. Unruh
1985 Volume 54 Issue 2 Pages
822-828
Published: February 15, 1985
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The structural phase transition in LiRbSO
4 has been reinvestigated by means of microscopic observation, dielectric measurement and X-ray scattering. The general feature of successive transitions was reconfirmed. But a new ferroelectric phase was found between the incommensurate phase II and the commensurate phase III, in a narrow temperature range around 473 K. The satellite reflections in this phase are characterized by a commensurate wavenumber
kz=(3⁄7)
c*. Under an electric field, the same modulation wavenumber is also recognized between the phase III and the ferrielectric phase IV, where fourfold D–E hysteresis loops are observed.
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