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Frank Göhmann, Miki Wadati
専門分野: Mathematical methods in physics.
1995 年 64 巻 10 号 p.
3585-3588
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The su(1|1) symmetric version of the Haldane-Shastry spin chain is diagonalized by means of a linear transformation. The same transformation applied to the original su(2) model yields simple expressions for the Hamiltonian and the generators of the Yangian symmetry of the model in terms of spin wave operators.
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Satoru Kurosaki
専門分野: Classical and quantum physics: mechanics and fields.
1995 年 64 巻 10 号 p.
3589-3592
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The bifurcation process of periodic orbits of the Hénon-Heiles Hamiltonian system is investigated by calculating residues. Threefold symmetry of the system induces bifurcations with triple branches, to which the generic bifurcation scheme proposed by Meyer can not be applied. Normal form analysis gives results consistent with numerically observed bifurcations.
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Ryutaro Sato, Yasuhiro Akutsu
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 10 号 p.
3593-3597
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The equilibrium crystal shape (ECS) for the body-centered solid-on-solid (BCSOS) model in the low-temperature phase is studied. Based on the equivalence between the BCSOS model and the asymmetric six-vertex model, the surface free energy f(ρ) (ρ: step density) is calculated for general mean surface tilt angle. In the expansion, f(ρ )=f(0)+α ρ+βρ
3+O(ρ
4), the universal relation between a and b is verified. Accordingly, the Gaussian curvature of the ECS is shown to assume a universal finite jump at any position of the facet edge of the crystal.
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Tomotoshi Nishino
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 10 号 p.
3598-3601
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The density matrix renormalization group (DMRG) method is applied to the interaction round a face (IRF) model. When the transfer matrix is asymmetric, singular-value decomposition of the density matrix is required. A trial numerical calculation is performed on the square lattice Ising model, which is a special case of the IRF model.
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Osamu Inomoto, Takayuki Ariyoshi, Seiji Inanaga, Shoichi Kai
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 10 号 p.
3602-3605
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Hydrodynamical effects due to Marangoni instability in the Big Wave, which is the wave observed in a quasi 2-dimensional shallow layer of unstirred excitable Belousov-Zhabotinsky (BZ) reaction solution, were investigated experimentally. We found that the layer depth of BZ solution strongly influences the propagating velocity and the shape of the wave. The critical depth d
c of BZ solution was found to be d
c≈ 1.5, mm. The qualitative feature of the propagation of the wave changed at d
c. We also determined the difference between the location of the maximum deformation of the surface and that of a wave front such as the color front.
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Yasutami Takada, Hiroshi Yamagami
専門分野: Electronic structure of atoms and molecules: theory.
1995 年 64 巻 10 号 p.
3606-3609
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
By applying the effective-potential-expansion method to a He atom, we have reproduced the exact total energy with an error of 0.1 discuss both long- and short-range aspects of the two-electron correlation around the nucleus.
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Hitoshi Hojo, Yasuyoshi Yasaka
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 10 号 p.
3610-3613
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Effects of radial transport on potential formation in the plug cell of a tandem mirror are studied. The radial transport equation including a mobility for potential-trapped electrons in the plug cell is solved numerically in the steady state. It is shown that radial particle diffusion-losses enhance the confining potential for plug-cell electrons, of which magnitude is obtained as a function of radial diffusion-loss time for different values of the mobility and for different profiles of the potential. It is also found that a hysteresis arises in the relation between the potential and the radial diffusion-loss time, which causes a mode transition.
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Hirotaka Yamaguchi, Toshimitsu Ito, Kunihiko Oka, Hiroyuki Oyanagi
専門分野: Lattice dynamics and crystal statistics.
1995 年 64 巻 10 号 p.
3614-3617
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
X-ray diffraction study has been performed on a single crystal of La
1.91Ba
0.09CuO
4 using a four-circle diffractometer. It is found that the crystal structure is orthorhombic (low-temperature-orthorhombic; LTO), but an extra reflection is observed at (½, ½, 0) in the high-temperature-tetragonal (space group I4/mmm) coordinates, which is forbidden by the extinction rule for the well-known LTO structure (space group Bmab), at 300, K. The intensity of the extra reflection is lower than that of the most intense fundamental reflection (1, 1, 0) by three orders of magnitude, but the sharp line shape suggests a long-range lattice modulation of the unit cell. The intensity exhibits no significant change in the temperature range down to 14, K. We also report the same kind of reflections in high-quality single crystals of La
2-xSr
xCuO
4.
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Jonathan Bird, Koji Ishibashi, Yoshinobu Aoyagi, Takuo Sugano
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3618-3621
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We demonstrate the generation of zero-current voltage fluctuations in quantum dots at high magnetic fields, where one or more edge states (ES) are trapped within the dot. While currently unable to provide a definitive model for the generation of the noise, we propose a possible mechanism in which time-dependent perturbations to the dot geometry, give rise to corresponding fluctuations in the coupling between the transmitted and confined ES. In other words, the voltage noise is thought to be a direct probe, of the time-dependent motion of the electronic distribution within the dot.
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Gennady Yu. LOGVENOV, Hiroshi Ito, Takehiko Ishiguro, Gunzi Saito, Sat ...
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3622-3625
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We report the experimental observation of the slow magnetic oscillation of the thermoelectric power in the ambient-pressure organic superconductor κ-(BEDT-TTF)
2Cu(NCS)
2 at magnetic fields up to 12, T perpendicular to the ab plane and under a temperature gradient along the b-axis in the temperature range of 3--15, K. The frequency of the oscillations F
s=6--7, T is -- 1 fundamental frequency of the closed α-orbit.
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Yasuhide Tomioka, Atsushi Asamitsu, Yutaka Moritomo, Yoshinori Tokura
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3626-3630
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Magnetotransport properties were investigated for a crystal of perovskite-type manganese oxide, Pr
1-xCa
xMnO
3 (x=0.3). The single-crystal compound is insulating and below 220, K shows the charge-ordering of Mn
3+ and Mn
4+ species. Application of a magnetic field (>20, kOe) changes a canted antiferromagnetic insulating state into a ferromagnetic metallic state accompanied by change of resistivity by several orders of magnitude. At low temperatures, e.g., <50, K, the hysteresis of the transition field is pronounced and the field-induced insulator-to-metal transition becomes irreversible.
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Shiho N. Okuno, Koichiro Inomata
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1995 年 64 巻 10 号 p.
3631-3634
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have found that the interlayer exchange coupling between two Fe layers separated by a Au spacer oscillates as a function of the Au cap layer thickness in a MBE-grown Au/Fe/Au/Fe/Au(001) sandwich structure. Two oscillations with periods of 2.6 ML and 8.0 ML were observed. The characteristics of the Au cap layer thickness dependence, namely the appearance of two oscillations and the values of their oscillation periods are the same as those for the Au interlayer. The behavior can be explained as arising from the quantum interference effect in the Au cap layer.
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Kosai Tanabe, Seiichi Seki
専門分野: Superconductivity.
1995 年 64 巻 10 号 p.
3635-3638
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A new type of solution is found of the one-dimensional Ginzburg-Landau equation for superconducting pairing gap Δ(x) coupled with magnetization M(x). It describes a periodic coexistence of superconductivity and magnetic order realized in an open system, which is stabilized by external electric current. Within a spatial period of this phase, d-- (8π
2c/a
0)
1/2(T
M-T)
-1/2, there appears a pair of magnetic domain walls at x=d/4 and 3d/4, where Δ(x) reaches its maxima. A novel feature is that such an order is induced and controlled by the electric current supplied from the external device, j, defining another order parameter related to the phase factor of the gap, ζ =mj/(h/2π) e-- (4α
30/27β
2γ )
1/2 (T
c-T)
3/2.
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Hitoshi Sugawara, Osamu Inoue, Yoshihiko Kobayashi, Hiroki Sato, Tsugu ...
専門分野: Superconductivity.
1995 年 64 巻 10 号 p.
3639-3642
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have succeeded in growing a high-quality single crystal of CeCo
2 which shows a clear de Haas-van Alphen oscillation. Using this single crystal, we have studied the superconducting properties related to the FFLO state.
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Yoshitami Ajiro, Kazumi Hanasaki, Takayuki Asano, Takeo Takagi, Mamoru ...
専門分野: Magnetic properties and materials.
1995 年 64 巻 10 号 p.
3643-3646
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Effect of impurities on the high-field magnetization process in a frustrated antiferromagnet CuFeO
2 is studied for powder samples of CuFe
1-xAl
xO
2 (0≤ x≤ 0.1) and CuFe
1-xCr
xO
2 (0≤ x≤ 0.08) using a pulse magnet up to 38, T. For the pure Fe compound distinct magnetization anomalies are successively observed at 7, 12 and 20, T due to the field-induced transitions originated from a subtle balance of competing interactions. These anomalies rapidly disappear with increasing impurity concentration. The effect of impurities is interpreted in terms of the magnetic domain model in which the collinear spin structure of the pure system survives locally as domains without coherence as a consequence of partial suppression of a geometrical frustration by impurities.
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Masayuki Hagiwara, Koichi Katsumata, Shinji Sasaki, Naoyuki Narita, Is ...
専門分野: Magnetic properties and materials.
1995 年 64 巻 10 号 p.
3647-3650
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Dc, linear ac and nonlinear ac susceptibility measurements on a nominally pure single crystal of the S=1 linear chain Heisenberg antiferromagnet Ni(C
2H
8N
2)
2NO
2ClO
4 (NENP) show clearly that a spin-glass transition takes place in this sample. A possible origin of this spin-glass freezing is discussed.
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Tetsuya Yokoo, Takehiro Sakaguchi, Kazuhisa Kakurai, Jun Akimitsu
専門分野: Magnetic properties and materials.
1995 年 64 巻 10 号 p.
3651-3655
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Magnetization measurement and inelastic neutron scattering have been performed on a single crystal of a new Haldane system Y
2BaNiO
5. Magnetic susceptibility shows a weak anisotropy and decreases as temperature decreases, reflecting the singlet ground state at low temperature. The energy gaps were found to be Δ
///k
B=118, K and Δ
⊥ /k
B=104, K, parallel and perpendicular to the chain, respectively. Using inelastic neutron scattering magnetic excitations along the chain (a
*-) and perpendicular (c
*-) directions up to 30, meV energy transfer are studied. Energy gap of about 10, meV (116, K) is observed along the one-dimensional, antiferromagnetic zone center, in good agreement with the magnetization measurement. The observed dispersion relation in the chain direction with the gap can be well described by the exact numerical results of S=1, Heisenberg antiferromagnetic chain yielding an intrachain exchange of J/k
B=280± 10, K.
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Shigeki Ohsugi
専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1995 年 64 巻 10 号 p.
3656-3659
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The nuclear quadrupole resonance (NQR) frequency, ν
Q, of
139La in La
2-xM
xCuO
4 (M=Sr, , Ba) was systematically measured in the Sr or Ba content range of 0\lex≥0.20 at 1.4 and 4.2, K in zero field. ν
Q, which is the principal component of the electric field gradient (EFG) tensor, decreases linearly with increasing x for both compounds, showing no appreciable change even around x-- 1/8 for Ba doping where the structural phase transition from orthorhombic to tetragonal structure occurs at low temperature.
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Sin–Ichi Hamazaki, Fuminao Shimizu, Seiji Kojima, Masaaki Takash ...
専門分野: Dielectric properties and materials.
1995 年 64 巻 10 号 p.
3660-3663
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We used atomic force microscopy (AFM) to study the surface morphology of tetragonal barium titanate BaTiO
3 at room temperature. An undulation of the surface was observed around the boundary of 90° domains of the as-grown surface of the so-called butterfly crystals, which can be reasonably explained by the tetragonality of this crystal at room temperature.
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Tetsuo Ogawa, Hiroshi Otani
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1995 年 64 巻 10 号 p.
3664-3667
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The Tomonaga-Luttinger liquids with spin-polarized Fermi points in an external magnetic field are studied theoretically. The critical exponent of the Fermi-edge singularity is analytically obtained. Power-law divergence of edge spectra is possible even for repulsive electron-hole interactions.
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Atsushi Nagai, Junkichi Satsuma
専門分野: Mathematical methods in physics.
1995 年 64 巻 10 号 p.
3669-3674
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
It is shown that a hierarchy of the Lotka-Volterra equations is generated from the QR algorithm to find eigenvalues of a given matrix. One of the equations in the hierarchy is given by dN
k/dt=N
k {N
k+1(N
k+N
k+1+N
k+2) -N
k-1(N
k-2+N
k-1+N
k)}, in which one species interacts with other four species. The relation between this hierarchy and the Toda lattice hierarchy is discussed. Moreover, the structure of soliton solutions is studied by means of the bilinear formalism.
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Taro Nagao
専門分野: Mathematical methods in physics.
1995 年 64 巻 10 号 p.
3675-3681
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Asymptotic correlation functions of the eigenvalues in the limit of large dimension of random matrices are evaluated for two models related to the Jacobi polynomials. One of the models is a generalization of Dyson's circular ensemble. Both models show identical unfolded correlations near a singularity of the spectrum. A previously unnoticed universal behavior of random matrix ensembles near a singularity is discussed.
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Toshiyuki Imai, Takeshi Fukuyama
専門分野: Mathematical methods in physics.
1995 年 64 巻 10 号 p.
3682-3687
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Aitken acceleration is used to prove a conjecture that solutions of Toda molecule equation lead to those of Ernst equation giving Tomimatsu-Sato solutions.
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Hiroshi Takano, Seiji Miyashita
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 10 号 p.
3688-3698
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A method of finding slow relaxation modes in random spin systems is proposed. For stochastic dynamics, an approximate relaxation mode {f
i} and its relaxation rate λ are determined from an eigenvalue problem ∑
j, C
i, j(t
0+t)f
j=exp, (-λ t), ∑
j , C
i, j(t
0)f
j, where C
i, j(t)=‹ S
i(t) · S
j(0)› is the correlation matrix of spins. The method is applied to the two-dimensional ± J Ising spin glass below the critical temperature of the corresponding nonrandom ferromagnet. It is found through Monte Carlo simulations that the slow relaxation modes obtained by the present method describe the long-time behavior of spins well. The slow relaxation modes are spatially localized and can be regarded as clusters. The distribution of the relaxation rates is consistent with the prediction of the theory which assumes independent motion of clusters.
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Makoto Inoue
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 10 号 p.
3699-3706
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The two-dimensional ± J random Ising model is studied numerically up to a system size 700× 701 by using the Pfaffian method which gives exact free energy and correlation functions. The behavior of the specific heat at the paramagnetic-ferromagnetic phase boundary is analysed by using logarithmic type, double-logarithmic type and cusp type of regression equations. It is found that the logarithmic divergence is the most natural behavior. The critical temperature is determined accurately.
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Shigeru Yamada, Taher Sharshar, Kazuhiko Aoki, Kotoyuki Okano
専門分野: Nuclear decay and radioactivity.
1995 年 64 巻 10 号 p.
3707-3717
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The level scheme of
177Lu following the β-decay of
177Yb (T
1/2=1.9, h) has been constructed from results of γ singles and γ-γ coincidence measurements. Angular correlations of γ-rays were measured with a 4-Ge detector system. Mixing ratios (E2/M1) of seven γ-rays were obtained. The spins and parities of the 1049.4, 1150.0 and 1241.7, keV levels have been assigned to be 9/2
-, 7/2
+ and 7/2
+, respectively. These assignments for the 1049.4 and 1241.7, keV levels are consistent with the interpretation that these levels are members of three-quasiparticle multiplets. Energy splittings of three-quasiparticle states were calculated. The calculated 1160, keV 7/2
+ level may correspond to the observed 1150.0, keV 7/2
+ level. A calculation with a rotation-vibration coupling model was performed. The K-2 γ-vibrational state of the 7/2
+[404] state and the K± 2 γ-vibrational states of the 9/2
-[514] state are expected to exist near 1300, keV.
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Jirohta Kasagi, Takeshi Murakami, Tohru Yajima, Shiho Kobayashi, Masao ...
専門分野: Nuclear reactions and scattering: general.
1995 年 64 巻 10 号 p.
3718-3724
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The D+D reactions in Ti metal were investigated for the deuteron incident energies between 4.7 and 18, keV. Observed were protons, tritons and
3He particles emitted in the deuteron bombardment on TiD
x. Thick target yields for the D(d, , p)T and D(d, , n)
3He reactions were measured at bombarding energies down to 4.7 and 5.4, keV, respectively, for the first time. They were well explained with the reported astrophysical S-factors which were deduced from gas target measurements at E
d>6, keV for the D(d, , p)T reaction and E
d>13.3, keV for the D(d, , n)
3He reaction. The cross section ratio σ(d, , p)/σ(d, , n) was obtained down to 6.4, keV, and was found to be constant at around 1.0 for E
d<20, keV.
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Hiroaki Fukuta, Youichi Murakami
専門分野: Fluid dynamics.
1995 年 64 巻 10 号 p.
3725-3739
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Stability of Kolmogorov flow: U=-sin y to any finite disturbances is treated by using the energy method. The linear damping term -λ u due to the bottom friction is taken into account. The Euler-Lagrange equation is solved numerically and analytically to determine the critical Reynolds number, R
Ec, below which subcritical instability cannot occur. It is shown numerically that R
Ec and the linear critical Reynolds number, R
Lc are of the same order in 0<λ <200. The critical wavenumber, (α
Ec, , β
Ec) is always (0, , 0) when λ <49.1; otherwise α
Ec≠ 0. By using a small wavenumber expansion, it is obtained that R
E= [8λ (λ +1)]
1/2 at α=0. In the limit λ → ∞, numerical results suggest that R
Ec→ 2λ and α
Ec→ ∞. In this limit for general parallel flow U(y) the relation: (2/M)λ
EcLc=(1/σ0)λ is obtained analytically where M=maxy, | ∂ U/∂ y|, and σ0 is the inviscid maximum growth rate.
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Tohru Nakano
専門分野: Fluid dynamics.
1995 年 64 巻 10 号 p.
3740-3747
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
In the present paper we have carefully examined the behavior of Q
p(r), the moments of the enstrophy dissipation rate in two-dimensional turbulence averaged over squares of size r. We found a new scaling relation between Q
p(r) and Q
p-1(r), which helps to establish the existence of two scaling regimes of Q
p(r) in the large and small r region. The crossover scale is the length of the strips where the strong enstrophy dissipation occurs. If the length is much longer than the dissipation length corresponding to the width of the strips, such a scale is expected to naturally come in the scaling of Q
p(r), casting a doubt on the usual statement that there is no characteristic length in turbulence. The implication of the result is discussed in relation to three-dimensional turbulence.
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Shinsuke Watanabe, Koji Nakamichi, In–Sung Jang, Kenya Kazama, S ...
専門分野: Kinetic and transport theory of fluids; physical properties of gases.
1995 年 64 巻 10 号 p.
3748-3757
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A method is presented for generating a vortex ring in water by an exploding wire installed in a metal pipe. As a vapor bubble accompanied by wire explosion grows, water starts to flow with a high speed resulting in a formation of a vortex ring at the outlet of the pipe. The growth speed of a vapor bubble by the exploding wire in water is measured as 10-- 20, m/s, in consistent with measurements of the translational velocity, 4-- 5, m/s, of vortex ring and the rotational velocity, about 10, m/s, of fluid at the edge of vortex core. The Reynolds number based on the diameter of orifice, the velocity of vortex ring and the kinematic viscosity reaches the order of 10
5. The magnitude of vorticity and the circulation are in the order of 10
3/s and 10
-1, m
2/s. These values are larger by about 10 times than those reported previously.
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Mohammad Salimullah, Brahmananda Dasgupta, Kunihiko Watanabe, Tetsuya ...
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 10 号 p.
3758-3766
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The dispersion characteristics of the circularly polarized electromagnetic waves propagating along a homogeneous magnetic field in a dusty plasma have been investigated theoretically. The Vlasov equation has been employed to find the response of the magnetized plasma particles where the dust grains form a static background of highly charged and massive centers having certain correlation. It is found that in addition to the usual Landau damping which is negligible in the low temperature approximation, a novel mechanism of damping of the Alfvén waves due to the dust comes into play. The modification and damping of the Alfvén waves depend on the dust perturbation parameters, unequal densities of plasma particles, the average correlation length of the dust grains, temperature of the plasma and the magnetic field.
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Chang Lin, Xiu–lian Zhang
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 10 号 p.
3767-3769
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A general analytical solution for the three-dimensional Poisson equation has been obtained for the nonlinear Debye screening in plasmas. We derive an exact analytical expression for T
e=T
i and an approximate expression for T
e≠ T
i for the three-dimensional nonlinear Debye potential.
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Takashi Sakuma, Takashi Aoyama, Yoshimi Tsuchiya
専門分野: Structure of liquids and solids; crystallography.
1995 年 64 巻 10 号 p.
3770-3774
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A general expression of the scattering intensity for non-crystalline materials has been proposed by introducing the correlations of the thermal displacements of atoms. The statistical average of the scattering intensity consists of two contributions; thermal vibrations and static disordered arrangements. The profiles of the X-ray scattering intensity for amorphous Pd
80Si
20 and the neutron thermal scattering intensity for amorphous Ge are discussed with the present theory including the correlations of the thermal displacements of atoms.
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Hiroshi Orihara, Yoshihiro Ishibashi
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 10 号 p.
3775-3786
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have theoretically studied the electro-optic effect and third-order nonlinear dielectric response in antiferroelectric liquid crystals on the basis of phenomenological equations of motion. It has been found that the antiferroelectric soft and Goldstone modes can be excited by an electric field, though they respond to the square of the field but not to the field itself, and they modulate the dielectric constant both for the visible light and low frequencies, contributing to the electro-optic effect and the third-order nonlinear dielectric response, respectively. The transmitted intensity and the third-order dielectric constant were theoretically derived, and the former was compared with experimental results.
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Tomonori Koda, Hatsuo Kimura
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 10 号 p.
3787-3797
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A chiral rod-like molecule has the head-tail asymmetry, so that the pair potential between such molecules in head-to-head configuration is naturally different from the potential of those in tail-to-tail or head-to-tail configuration. Taking the head-tail asymmetry into account, we propose a simple model of chiral smectics and calculate the free energy of possible phases in a mean field approximation. The results show that the head-tail asymmetry can contribute to stabilize certain type of antiferroelectric phase between the ferroelectric smectic-C
* phase and the antiferroelectric smectic-C
*A phase.
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Yoshihiro Kuroiwa, Hideaki Muramoto, Takahisa Shobu, Hiroaki Tokumichi ...
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 10 号 p.
3798-3803
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
X-ray diffraction experiments have been performed near the ferroelastic first-order phase transition temperature in lanthanum niobate LaNbO
4, which transforms from a tetragonal phase to a monoclinic phase at T
c=768, K with a discontinuous change of the lattice parameter Δβ =0.4°. With regard to the temperature dependence of the Bragg reflection near T
c, such pretransitional phenomena as decreasing of the peak intensity and broadening of the profile were observed. Furthermore, in the high temperature phase, as the temperature was close to T
c, the anisotropic diffuse scattering around the Bragg reflections extended to the directions where the Bragg reflections in the low temperature phase appeared was observed. These behaviors were contrasted with the well known precursor phenomena of the martensitic phase transformation in metals and alloys.
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Hiroki Nagashima, Hiroyuki Okamoto, Yuuichi Okada, Yutaka Ishihara
専門分野: Thermal properties of condensed matter.
1995 年 64 巻 10 号 p.
3804-3810
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The specific heats of niobium chalcogenide Nb
3S
4, Nb
3Se
4 and Nb
3Te
4 have been measured in the temperature range from 0.5 to 150, K. The lattice contribution to the specific heat of Nb
3S
4 and Nb
3Se
4 deviates from a T
3 dependence at about 13 and 7, K and then changes to a T
1 dependence with increasing temperature. The lattice-specific heat of Nb
3Te
4 deviates from a T
3 dependence near 2, K, changing from T
3 to rough T
2.2 and then begins saturate toward the classical value with increasing temperature. The anisotropy in force constants that causes these behaviors is discussed in relation to the crystal structure of Nb
3X
4.
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Hideo Yoshioka, Yoshikazu Suzumura
専門分野: Electron states in condensed matter.
1995 年 64 巻 10 号 p.
3811-3825
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Two chains of interacting spinless fermions in the presence of interchain hopping are investigated by use of phase Hamiltonian based on bosonization method. Excitation spectrum and phase diagram at absolute zero temperature are obtained by means of renormalization group method. Momentum distribution functions are also calculated. It is shown that the interchain hopping gives rise to drastic effects on properties of ground state compared to interchain interaction and is crucial to appearance of ordered states in higher dimensions.
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Ken Deguchi, Yoshiaki Ohno, Tamifusa Matsuura, Yoshihiro Kuroda
専門分野: Electron states in condensed matter.
1995 年 64 巻 10 号 p.
3826-3839
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Effects of a single impurity in the degenerate lattice Anderson model describing heavy elecron systems are investigated rigorously within the framework of the axiliary boson method and the perturbation expansion from the large limit of the spin-orbital degeneracy N (1/N-expansion). It is found that a non-magnetic impurity leads to the unitarity limit value of the scattering rate of the conduction electrons at low temperature while it has no appreciable effect on the thermodynamic properties. These results are consistent with the experimental observations on the heavy electron systems such as Ce
1-xLa
xCu
6.
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Chikara Sugiura
専門分野: Electron states in condensed matter.
1995 年 64 巻 10 号 p.
3840-3852
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The P Kβ emission and S Kβ emission spectra in fluorescence from many selected compounds, P
4O
10, KPF
6, M
4P
2O
7, M
2SO
3, M
2SO
4, MHSO
4 (M=Na and K), P
4S
n (n=3, , 5, , 7 and 10), Na
2S
2O
n (n=3--7) and K
2S
2O
n (n=3, , 5, , 7 and 8), are measured with a high-resolution two-crystal vacuum spectrometer equipped with Ge(111) crystals. The measured Kβ emission spectra are discussed in relation to the fundamental structures of the compounds and interpreted in terms of available molecular-orbital calculations of the PF
-6 ion and sulfur oxo anions. It is shown that the emission spectra are strongly influenced by chemical environments around phosphorus and sulfur atoms in the compounds, but little affected by the metal ions Na
+ and K
+.
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Keita Kishigi, Kazushige Machida
専門分野: Electron states in condensed matter.
1995 年 64 巻 10 号 p.
3853-3859
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have investigated the first order field induced phase transitions observed in α-(BEDT-TTF)
2MHg(SCN)
4 (M=K, Rb and Tl) by examining theoretically the energetics of the magnetic breakdown phenomena in high fields (H) which were understood as a probabilistic process. Since the diamagnetic energy loss associated with the cyclotron motion is effectively lowered by taking a larger orbit in reciprocal space as H increases, the spin density wave (SDW) gap formed on an orbit can be eliminated by the “break-through” electrons. An origin of the field-induced reentrant transition from SDW to the normal state in those quasi-two dimensional conductors is attributed to this energetics. The quantum magnetic oscillation is predicted to yield a novel type of successive phase transitions where two phases are interwoven in a fine scale against H.
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Hironori Sakamoto, Masafumi Shirai, Naoshi Suzuki
専門分野: Electron states in condensed matter.
1995 年 64 巻 10 号 p.
3860-3870
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Band structure calculations based on the full-potential linearized augmented-plane-wave method are performed for the metallic FCC phase of solid iodine. Pressures which are evaluated from the total energy as a function of the atomic volume agree well with the observations. The calculated Hall coefficients are positive and agree in order of magnitude with the experimental data. Contradicting with the observations, however, they decrease slowly as pressure increases. Pressure effects on the electron-lattice interaction are studied microscopically on the basis of the tight-binding scheme. The magnitude of the transfer integrals and their derivatives increase significantly with increasing pressure. As the results the McMillan-Hopfield parameter N(E
F)‹ ξ
2› increase with increasing pressure, which indicates a possibility of increase of the superconducting transition temperature with increasing pressure. Here N(E
F) denotes the desnity of states at the Fermi level and ‹ ξ
2› is the Fermi surface average of squaure of electron-phonon coupling.
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Shinji Nonoyama, Akira Oguri
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3871-3880
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The effect of on-site Coulomb repulsion on the process of resonant tunneling through a small interacting region is studied in the presence of a magnetic field by using the recursive Green's function method within a mean field approximation. The conductance is calculated as a function of the chemical potential μ making use of the Kubo formula, and calculations are performed for single- and double-mode quasi-one-dimensional quantum wires. In a magnetic field, some resonance levels close each other to form a single Landau level, so that the electron correlation in the small region is enhanced, and the μ-dependence of the conductance is changed by rather small value of the Coulomb repulsion. For the double-mode wire a collinear-type electronic state, in which spins in the small region are aligned antiferromagnetically in the x-direction and ferromagnetically in the y-direction, is found to be stable over a wide range of the chemical potential.
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Noriaki Kimura, Rikio Settai, Yoshichika Onuki, Hiroyuki Toshima, Etsu ...
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3881-3889
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have done the transverse magnetoresistance and the de Haas-van Alphen (dHvA) experiments in UPt
3. The magnetoresistance increases in the whole field direction. UPt
3 is thus a compensated metal, possessing no open orbits. As for the dHvA experiment, we have observed at least three new branches. One of them is in the basal plane and the others are around the [0001] direction. The branches with dHvA frequencies of 2.7× 10
7, Oe and 4.9× 10
7, Oe in the field along [0001] possess large masses of 40--50m
0. These results have been discussed on the basis of the 5f-itinerant Fermi surface model.
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Yukio Yasui, Takashi Nishikawa, Yoshiaki Kobayashi, Masatoshi Sato, Ta ...
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 10 号 p.
3890-3896
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Transport and magnetic measurements including the magnetic resonance of
51V nuclei have been carried out for misfit-layer compounds (La
1-yR
yS)
1+αVS
2 (R=Sr and Pb, 0≤ y≤ 1.0). The results indicate that the system is in the Mott insulating state at high temperatures, at least in the y region near α /(1+α) which corresponds to the V-valency of +3. It undergoes a transition with decreasing temperature possibly to a nonmagnetic ground state. With increasing carrier doping into this insulating state, the system tends to become metallic and an essentially metallic state is realized in the hole-doped region 0.30 x ≡ y(1+α )<0.5, where various properties are found to exhibit anomalous behavior similar to the case of high-T
c Cu-oxides.
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Junji Sakurai, Katsuhiro Hasegawa, Kazuhiko Shintaku, Teruya Shinjo
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1995 年 64 巻 10 号 p.
3897-3902
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
The thermoelectric power S of artificial magnetic multilayers of Fe/Au has been measured as functions of temperature T as well as magnetic field H. The magneto-thermoelectric power (MTEP) was found to have a negative sign. In addition, data of S of magnetic multilayers of Co/Cu hitherto published were reexamined in order of clarify its sample dependence, and MTEP for these multilayers was ascertained to have also a negative sign. The negative sign of MTEP of the two systems are discussed in relation to the theory developed by Inoue et al.
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Bruce Normand, Hiroshi Kohno, Hidetoshi Fukuyama
専門分野: Superconductivity.
1995 年 64 巻 10 号 p.
3903-3924
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We consider a bilayer version of the extended t-J model, with a view to computing the form of certain experimentally observable properties. Using the slave-boson decomposition, we show at the mean-field level that in the bilayer system the existence of in-plane d-wave singlet pairing excludes any interplane singlet order for reasonable values of the interplane superexchange parameter. Restricting the analysis to the regime of no interplane singlet pairing, we deduce parameter sets reproducing the Fermi surfaces of YBCO- and BSCCO-like bilayer systems. From these we calculate the form of the dynamic susceptibility χ(q, , ω) in both systems, and of the anomalies in frequency and linewidth of selected phonon modes in YBCO. We compare the results with experiment, and discuss the features which differ from the single-layer case.
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Ryusuke Ikeda
専門分野: Superconductivity.
1995 年 64 巻 10 号 p.
3925-3933
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
A hydrodynamical description for vortex states in type II superconductors is presented based on the time-dependent Ginzburg-Landau equation (TDGL). In contrast to the familiar extension of a single vortex dynamics based on the force balance, our description is consistent with the known hydrodynamics of a rotating neutral superfluid and correctly includes informations on the Goldstone mode. Further it enables one to examine nonlocal conductivities perpendicular to the field in terms of Kubo formula. Typically, the nonlocal conductivities deviate from the usual vortex flow expressions, as the nonlocality parallel to the field becomes weaker than the perpendicular one measuring a degree of positional correlations, and, for instance, the superconducting contribution of dc Hall conductivity nonlocal only in directions perpendicular to the field becomes vanishingly small in the situations with large shear viscosity, leading to an experimentally measurable relation ρ
xy-- ρ
2xx among the resistivity components. Other situations are also discussed on the basis of the resulting expressions.
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Hitoshi Ohta, Shojiro Kimura, Mitsuhiro Motokawa
専門分野: Magnetic properties and materials.
1995 年 64 巻 10 号 p.
3934-3940
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
Antiferromagnetic order of Y
2BaCuO
5 has been observed by submillimeter wave ESR in the frequency region from 90 to 383, GHz using pulsed magnetic field up to 16, T. Transition temperature is determined to be around 15, K using powder sample. The results suggest easy-plane type anisotropy and they are analyzed in the framework of molecular field theory. The result of the magnetization measurement is also presented.
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Shintaro Nakamura, Terutaka Goto, Satoru Kunii
専門分野: Magnetic properties and materials.
1995 年 64 巻 10 号 p.
3941-3945
発行日: 1995/10/01
公開日: 1999/10/01
ジャーナル
認証あり
We have studied the magnetic phase diagrams of the dense Kondo compounds CeB
6 and Ce
0.5La
0.5B
6 by use of low temperature ultrasonic measurements. A transition associated with a quadrupolar reorientation has clearly been observed around 1, kOe in the antiferroquadrupolar phase II of CeB
6. In the paramagnetic phase I of Ce
0.5La
0.5 B
6 a crossover from the ordinaly Γ
8 ground state to the Kondo singlet state has been found. The field induced transition from the Kondo singlet state to the antiferromagnetic phase III or the phase II has been found at a critical field 17, kOe. The field angle dependence of the phase diagram of Ce
0.5La
0.5B
6 is also presented.
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