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Yutaka Toyozawa
1989 年 58 巻 7 号 p.
2215-2218
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Arguments are presented for the viewpoint that irreversibility is inherent in quantum mechanics, irrespective of the number of particles participating. This fact is related to the notion of transition—ramifying evolution—which is characteristic of quantum mechanics. It is in contrast to classical mechanics based on the notion of orbit, where the irreversibility arises only as the result of a large number of particles or a certain complexity of the system. The statistical assumption needed for the derivation of irreversibility in classical mechanics is absorbed into the uncertainty principle of quantum mechanics, and is revived as inherent irreversibility. The statements conform with the parallelism of quantum mechanics and classical statistical mechanics emphasized in a previous report.
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Yasuhiro Akutsu
1989 年 58 巻 7 号 p.
2219-2222
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
For a solvable
N-state vertex model in the low-temperature antiferroelectric phase, exact per-site free-energy
f is calculated as a function of the order-parameter
p (‘vertical polarization’), based on the quantum inverse scattering method. The Bethe-ansatz integral equation is solved as an expansion with respect to
p, which leads to the Gruber-Mullins-Pokrovsky-Talapov-type expansion,
f(
p)=
f(0)+
a·|
p|+
b·|
p|
3+
O(|
p|
4). It is found that the coefficients
a and
b are identical to those of the six-vertex model (
N=2 case). This fact gives support for the
universal Gaussian curvature jump for the
N-state vertex model interpreted as a model of interface roughening.
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Masanori Takaoka
1989 年 58 巻 7 号 p.
2223-2226
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The stability of one parameter family of isosceles triangular cell flows represented by the stream function
Φ=sin
y (cos
y+cos α
x) is investigated. The periodicity of these flows in two directions permits us to employ Floquet theory to investigate the instability characteristics. The critical Reynolds number is given by long- or intermediate-wave disturbances depending on the parameter α. Even in the former case, the stream function of the disturbance does not necessarily converge to a constant function in the long-wave limit, in contrast to the other cases studied before.
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Ken-ichi Hattori
1989 年 58 巻 7 号 p.
2227-2230
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Behaviors of
m=1 kink modes of reversed field pinch plasmas are analyzed in the presence of field errors at shell gaps due to vertical field penetration. Perturbations in the vacuum and in the plasma are respectively expressed by using a class of modified Bessel functions and Bessel functions with
m=1 modes and matched on the boundary. It has been shown that
m=1 perturbation is amplified by the response of the plasma and its stability is deteriorated by the shell-gap field errors. Comparison with experiments is also discussed.
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Yuichi Akahama, Yoshihisa Mori, Mototada Kobayashi, Haruki Kawamura, K ...
1989 年 58 巻 7 号 p.
2231-2234
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
X-ray diffraction analysis under high pressure was performed on the icosahedral phase of an Al
6Li
3Cu alloy. The icosahedral phase was isotropically compressed under pressure. Above 10 GPa, however, a broad glassy background developed, while the diffraction peaks from the I-phase began to decrease markedly in intensity. This is the first observation of pressure-induced amorphization from the I-phase. At 28 GPa, new diffraction peaks developed from the glassy background. On release of pressure, the new peaks disappeared but the glassy background still remained after a month.
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Gendo Oomi, Atsuto Okamoto, Yoshichika \={O}nuki, Takemi Komatsubara
1989 年 58 巻 7 号 p.
2235-2237
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Thermal expansion coefficients α(K
−1) of single crystalline CeInCu
2 have been measured from 4.2 K to 300 K by means of the strain gauge method. The α along the [110] direction is very large at low temperatures below ∼100 K compared with that of LaInCu
2 which has no 4f electron. This fact implies that there is a large contribution from the 4f electron in CeInCu
2 to the magnitude of α. The results are discussed with regard to the crystalline electric field splitting of the Ce
3+ ion.
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Katsuyoshi Kobayashi, Masaru Tsukada
1989 年 58 巻 7 号 p.
2238-2241
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The tunnel current in the scanning tunneling microscopy (STM) of graphite is numerically simulated using the bonding and the antibonding orbitals of H
2 as a model of the tip. The normal image of the triangular lattice is obtained by the bonding orbital. But the image by the antibonding orbital is very much distorted; in an extreme case, it is the shape of linear chain which is often observed in the actual STM. It is caused by the special wave function of graphite near the Fermi level and the interference of the current contributed by the two tip atoms.
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Ken-ichi Takarabe, Shigeru Minomura, Masaaki Nakayama, Hiromu Kato
1989 年 58 巻 7 号 p.
2242-2243
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
Photoluminescence spectra of MBE-grown (GaAs)
12(AlAs)
12 superlattices under high pressure and low temperature are measured. Two main emission bands are observed. The higher emission band behaves like a
Γ-edge under pressure; the lower emission band, on the other hand, behaves like an
X-edge. This result shows that the
Γ−
X crossover occurs beyond the twelfth layers in (GaAs)
m(AlAs)
m superlattices.
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Kazushige Machida, Masa-aki Ozaki
1989 年 58 巻 7 号 p.
2244-2247
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The successive superconducting (SC) transitions observed in UPt
3 are explained as arising from the unconventional nature of the pairing state intrinsic in heavy fermion materials. Entirely from reasons of symmetry based on group theory, we have found a nontrivial coupling of two order parameters: the preexisting antiferromagnetism and the degenerate pairing state, which ultimately leads to the splitting of the SC transition temperature. Thermodynamic behaviors of this phenomenon are discussed.
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Makoto Hikita, Yukimichi Tajima, Hiroyuki Fuke, Kiyohiro Sugiyama, Mun ...
1989 年 58 巻 7 号 p.
2248-2251
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The high-field magnetoresistance of well-characterized LnBa
2Cu
3O
y (Ln=Ho, Dy, Eu and Y) single crystals has been measured from 4.2 K to 300 K under a pulsed magnetic field up to 60 T. The upper critical field
Hc2 is well sketched by the usual anisotropic BCS model and the normal resistivity down to liquid helium temperature shows that the system can be regarded as normal metal with positive magnetoresistance. The residual resistivity is between 10 and 50 μΩ cm, reflecting a highly qualified sample preparation. The relations among upper critical field, coherence length and normal resistivity are discussed. It is concluded that the magnetic rare-earth ions Ho and Dy enhance
Hc2 without affecting
Tc.
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Hiroshi Sawa, Kazuhiko Obara, Jun Akimitsu, Yoshio Matsui, Shigeo Hori ...
1989 年 58 巻 7 号 p.
2252-2255
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
A new family of high-
TC superconductors (Ln
1−xCe
x)
2(Ba
1−yLn
y)
2Cu
3O
10−δ (Ln: Nd, Sm, Eu) has been found by resistivity and magnetization measurements. The highest onset transition temperature is about 43 K. The structure is proposed on the basis of electron diffractions and Rietveld analysis of powder X-ray diffraction data.
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Yuji Yamaguchi, Madoka Tokumoto, Shinya Waki, Yoshihiko Nakagawa, Yoic ...
1989 年 58 巻 7 号 p.
2256-2259
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Magnetic susceptibility was measured on grain-oriented YBa
2Cu
3O
y (
y≈6.1 to 7.0). A distinct kink was observed in the susceptibility-vs-temperature curve at 435 K for
y≈6.1, when the external field was parallel to the
c-axis. The kink is attributed to an antiferromagnetic transition and the magnetic susceptibility is well explained as a typical quadratic Heisenberg antiferromagnet with an exchange-interaction parameter of ∼950 cm
−1 in the Cu(2) plane. The magnetic behavior changes gradually to the temperature-independent susceptibility of superconducting samples (
y≈7.0) with nearly constant parameters of anisotropy.
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Kazuo Hida
1989 年 58 巻 7 号 p.
2260-2263
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The slave fermion method is applied to the study of the ground state properties of the two-dimensional coupled spin-fermion model which describes the Cu–O plane of the high-
Tc oxide superconductors. It is found that the antiferromagnetic spin structure of the Heisenberg spin system is deformed into an incommensurate one in the presence of the fermions. For low fermion densities, a single incommensurate magnetic order appears, while for higher fermion densities, either the mixed phase of two incommensurate magnetic orders or the nonmagnetic phase appears depending on the model parameters. It is also shown that the effective interaction between the fermions is attractive for low fermion densities.
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F. Tchoffo, B. Lemius, S. Domngang
1989 年 58 巻 7 号 p.
2264-2267
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The valence instability phenomenon is studied in the mixed-valent system (Ce
xLa
1−x)Be
13 in the usual temperature range 4.2 to 300 K and for
x≤20% using the Nuclear Magnetic Resonance (NMR) spin-echo technique. The results obtained reveal that the spin-lattice relaxation rate of
9Be nucleus due to Ce impurities in (Ce
0.02La
0.98)Be
13 does not depend on temperature. This behaviour is identical to that observed in normal magnetic Rare Earth Beryllides and we have then deduced that there is a narrow range of concentration in the series (
x<5%) where Cerium ions are trivalent.
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Norio Akiyama, Yuzo Mori, Hiromasa Hanzawa, Hiroshi Ohkura
1989 年 58 巻 7 号 p.
2268-2271
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
By adopting Mezger and Jaccard’s method, we have optically determined the isotropic and anisotropic hyperfine (hf) parameters for the K nuclei at the fifth shell in the ground state of the
F center in KCl at 4.2 K. We have found three additional facts: (1) the hf signal intensity is decreased with an increase of the frequency of the modulation field superimposed on the static magnetic field; (2) the spin-lattice relaxation time in the relaxed excited state is an important factor for the occurrence of the hf signal; (3) the hf signal intensity is independent of the excitation power,
P, in the low magnetic field range. However, it is reduced with an increase in
P of the high-power pulse laser.
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Kunihiko Morimoto, Tadamiki Hihara
1989 年 58 巻 7 号 p.
2272-2275
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Temperature dependence of the spin-lattice relaxation time
T1ρ of
2D in a rotating frame has been measured in ammonium perchlorate ND
4ClO
4 and NH
4−xD
xClO
4 (
x=0.8). The temperature dependences of
T1ρ show minima due to the effect of rare spin
17O (0.037% in natural abundance). The relaxation in ND
4ClO
4 is of single exponential type, while in partially deuterated NH
4−xD
xClO
4, it is of an extremely nonexponential type. It was found that the relaxation rate
T1ρ−1 due to
17O spin in partially deuterated NH
4−xD
xClO
4 is enhanced by about 10 times that of pure ND
4ClO
4. Because of this enhancement, the measurement of
T1ρ of
2D in partially deuterated compounds is useful for confirming the relaxation via rare nuclear-spin and investigating the dynamic motion of oxygen atoms.
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Takehisa Yoshinari, Takao Nanba, Shigetaka Shimanuki, Masami Fujisawa, ...
1989 年 58 巻 7 号 p.
2276-2279
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The reflection spectra of (C
nH
2n+1NH
3)
2CdCl
4 were measured in the photon energy region of 0.5–25 eV at room temperature (RT) and liquid nitrogen temperature (LNT) by means of synchrotron radiation. It was found that absorption spectra of the present crystals resemble that of CdCl
2 crystals except for an additional peak at 5.10 eV (RT). The energy of the additional peak shifts with temperature by as much as 0.38 eV from 5.10 eV (RT) to 5.48 eV (LNT). This absorption peak has doublet structure and the splitting energy is 0.1 eV, which is the same magnitude as the spin-orbit splitting of a chlorine atom. The band is assigned to be an electronic transition from the chlorine 3
p valence band to a new-type conduction band which is composed of alkylammonium bases and is below the ordinary Cd 5
s conduction band in energy.
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Akio Yamagishi, Tetsuya Takeuchi, Terumasa Higashi, Muneyuki Date
1989 年 58 巻 7 号 p.
2280-2283
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
Diamagnetic alignment of polymerized organic molecules is discussed both from the theoretical and experimental points of view. When a number of molecules aggregate with their diamagnetic principal axes along the same direction, the resultant diamagnetic anisotropy energy becomes comparable to the thermal energy and the aggregated molecule can align under a conventional magnetic field, even at room temperatures. Polymerization of fibrin molecules is observed under magnetic fields up to 8 Tesla and considerable alignment is found. Partial alignment is seen even at 1 Tesla which means that blood clotting is influenced by use of the conventional superconducting magnet.
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Ryogo Hirota
1989 年 58 巻 7 号 p.
2285-2296
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Soliton solutions τ(
x) to the BKP hierarchy
[(
D3−
D13)
D−1+3
D12]τ·τ=0,
[
D16−5
D13D3−5
D32+9
D1D5]τ·τ=0,
………·
are expressed by the pfaffians denoted by (1, 2, …, 2
n):
τ=(1, 2, …, 2
n),
whose (
i,
j) elements are given by
(
Remark: Graphics omitted.)
where
Cij(=−
Cji) are constant and all
fi(
x) satisfy the linear differential equations
(
Remark: Graphics omitted.)
for odd
n and for
i=1, 2, …, 2
n.
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Masakazu Ichiyanagi
1989 年 58 巻 7 号 p.
2297-2304
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
What kind of ensemble has to be used for describing general nonequilibrium behavior is one of the unsolved problems of nonequilibrium statistical mechanics. We would like to propose a formalism for nonequilibrium many-body systems which follows the spirit of Gibbs’ ensemble theory. We shall set forth a new perspective of Kirkwood’s time-smoothing operation to define the initial density matrix. We will show that such an initial density matrix may be employed to prove the positivity of entropy production.
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Masakazu Ichiyanagi
1989 年 58 巻 7 号 p.
2305-2315
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The concept proposed by Kirkwood that a macroscopic quantity is the time average of the ensemble average of the corresponding dynamical operator is examined in detail. This concept provides us with a new possibility of studying nonequilibrium macroscopic systems. The method to be used here is based on the fact that a time-smoothed density matrix also satisfies the original Liouville-von Neumann equation for the unsmoothed one. Forms of nonequilibritum density matrix are given as exact solutions to it. In characterizing thermodynamically the density operators the use of the Gibbs-Duhem relation is made. A generalized version of Kubo formula is obtained for nonequilibrium systems in the hydrodynamical stage. The present method is also applicable to nonlinear dynamical systems.
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B. S. Grewal, H. S. Sahota
1989 年 58 巻 7 号 p.
2316-2319
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Analytic expressions have been developed for the electric quadrupole transition rates within the SU(3) limit of Interacting Boson Approximation for the intra gamma band transitions in even-even nuclei. The calculated values in
166,168Er agree with the experimental as well as the theoretical one’s, obtained using the complicated technique of numerical analysis.
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Akihiro Kajita, Yahachi Saito, Tsuneo Yasue, Manabu Hayashi, Ayahiko I ...
1989 年 58 巻 7 号 p.
2320-2324
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
Ionization profiles in the threshold region (7.05 to 8.40 eV) have been measured for Bi
n (
n≤4) by using synchrotron radiation, which crosses a molecular beam coupled with a time-of-flight mass spectrometer. Resonance lines due to autoionization are observed only for monomer. The photoionization spectrum of Bi
2 shows a depletion of intensity, which indicates a predissociation of Bi
2 to Bi
++Bi. Bi
3 and Bi
4 show only slowly varying profiles.
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Kazuo Sakai
1989 年 58 巻 7 号 p.
2325-2329
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Motions of particles in the beats of two noncollinear laser beams with the same linear polarization in vacuum are studied. It is shown that the beats propagate with a velocity smaller than the velocity of light and can trap charged particles by the relativistic ponderomotive four-force. The trapping condition, the maximum energy gain and the acceleration gradient are derived. The effect of the radiation loss is also examined.
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Geraldo Alexandre Barbosa
1989 年 58 巻 7 号 p.
2330-2337
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
An optical device that utilizes a semiconductor switch and parametric luminescence from a non-inversion symmetric crystal is proposed to generate a light beam with sub-Poissonian number variance. Numerical estimates based on a simplified model indicate qualitative features of the optical switch and the signal intensity achieving sub-Poissonian variance. The calculation is exemplified with parameters from a GaAs–AlGaAs multiple-quantum well structure (MQW) within a Fabri-Perot cavity. Conjugated beams (for example, λ
1=8322 Å and λ
2=8230 Å) from the down-conversion luminescence in a KDP crystal are selected by a pinhole system and directed to the MQW. Non-linear refractive index changes are induced by fluctuations in the pump beam (λ
2) matched to an excitonic level (
N=1) of the bi-dimensional GaAs and modulates the cavity compensating for identical fluctuations in the signal beam (λ
1).
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Kimie Nakashima, Naokata Takeyama
1989 年 58 巻 7 号 p.
2338-2345
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Based on the collision-theoretical results by Longuet-Higgins, Pople, and Valleau for a binary hard sphere mixture, thermal diffusion is discussed at the most elementary level to formulate it consistently with linear nonequilibrium thermodynamics without using the two-step logic outlined by the above authors. In accordance with the previous proposition by the present authors (J. Phys. Soc. Jpn.
57 (1988) 3332), specific enthalpies
transported and
of transport play an important role in maintaining the consistency under the Onsager reciprocal relation. Individual quantities
transported and
of transport are explicitly formulated, of which the quantities
of transport are subject to an analogue of the Gibbs-Duhem equation at constant temperature and pressure to validate an equation for the sum of the mechanical and thermodynamic forces.
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Masahiro Nakagawa
1989 年 58 巻 7 号 p.
2346-2354
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The elastic free energy of the incompressible ferroelectric SmC
* is constructed in a tensor formalism based on the symmetry argument of the monoclinic structure. Extracting some surface contributions from the total free energy, we find that such a monoclinic SmC
* phase permits 9 nonchiral, 2 chiral, 1 piezoelectric, and 9 flexoelectric terms in the bulk energy. In addition, the present expression for the elastic free energy is found to be somewhat simplified compared with that previously derived by Dahl and Lagerwall because of the reduction of a certain cross term in their expression. Finally the Euler-Lagrange equations for the layer distortion and the
c-director deformation are derived on the basis of the presently proposed elastic free energy.
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Masayuki Oikawa, Takashi Karasudani, Mitsuaki Funakoshi
1989 年 58 巻 7 号 p.
2355-2364
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The linear stability of two-dimensional steady flows between two long, eccentric, rotating circular cylinders is studied numerically under the condition that the inner cylinder rotates uniformly while the outer one is at rest. By using the pseudospectral method it is found that the critical Reynolds number increases with the eccentricity ε. The critical axial wave number is found to remain nearly constant for small ε and to increase with larger ε. The eigenfunctions are distributed in the region from the position of the maximum gap to 180° downstream of that position. The Taylor-vortexlike three-dimensional steady flows are computed for several supercritical Reynolds numbers. The torques acting on the cylinders and the position of maximum vortex activity are calculated.
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Toshiyuki Gotoh
1989 年 58 巻 7 号 p.
2365-2379
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Passive scalar diffusion in two dimensional turbulence is considered on the basis of Lagrangian renormalized approximation. The probability density function for particle pair dispersion is found to be selfsimilar in the energy cascading range and to be lognormal in both the enstrophy and the viscous convective ranges. The spectrum
F(
k) of scalar fluctuations is found to be
F(
k)=
Csχε
−1⁄3k−5⁄3 with
Cs=0.198 in the energy cascading range,
F(
k)=
Cs′χβ
−1⁄3k−1{ln (
k⁄
kI)}
−1⁄3 with
Cs′=0.561 in the enstrophy cascading range,
F(
k)=\sqrt6χ(ν⁄ε)
1⁄2k−1 in the viscous convective range and
F(
k)’s in other ranges are also shown. It is shown that in the enstrophy inertial range the turbulent diffusivity is dominated by large scale eddies. The evolution of the mean square distance of the particle pair is compared with the data of ballon release experiments by Er–El and Peskin (J. Atmos. Sci.
38 2264 (1981)).
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Shigeo Kida, Koji Ohkitani, Michio Yamada
1989 年 58 巻 7 号 p.
2380-2385
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The process of complexity is investigated in the motion of an incompressible viscous fluid. The Navier-Stokes equation is solved numerically in a cyclic box with an external force by use of the spectral method with a resolution of 84
3. High symmetry is imposed on the velocity field. The complexity of the flow is characterized by the spectral structure of the temporal variation of the kinetic energy. It is found that as the Reynolds number is increased, the temporal behavior of the velocity field undergoes the following series of transitions: steady→simply periodic→doubly periodic→triply periodic→nonperiodic (chaotic) motions.
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Makoto Okamura, Masayuki Oikawa
1989 年 58 巻 7 号 p.
2386-2396
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
We give some instability characteristics of two-dimensional finite amplitude surface waves on a linear shearing flow to three-dimensional infinitesimal rotational disturbances using a numerical method. We have found three kinds of instabilities: two of them are related with four- and five-wave resonances and the rest is intrinsically caused by a shearing flow. The growth rates of instabilities associated with four- and five-wave resonances are larger than those without a shearing flow for the same wave steepness.
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Zensho Yoshida, Hiroshi Yamada, Kimitaka Itoh, Sanae-I. Itoh
1989 年 58 巻 7 号 p.
2397-2401
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
The electron thermal transmission has been estimated for wavy electrostatic potentials which appears in structurally unstable electrostatic plasmas with Mach numbers less than unity. Wavy solutions of the potential are obtained by nonlinear analysis of the Bohm equation with the Sagdeev potential for the sheath problems.
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V. Petrillo, C. Riccardi, C. Maroli, G. Lampis
1989 年 58 巻 7 号 p.
2402-2413
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The propegation and absoption of ordinary waves in the range of the second harmonic of the electron cyclotron frequency in a hot and dense plasma, have been analyzed by means of a wave-dynamical approch. The existence of two different mode conversion schemes, occuring respectively when the injection takes place from the low or from the high megnatic field side, is shown. From the low megnetic field side, the ordinary wave is converted into an extraordinary mode, successively transformed into quasielectrostatic (
Q) modes, and finally, into Bernstein waves. From the high field side, no connection with Bernstein waves is possible, and, therefore, the ordinary mode produces only extraordinary and quasielectrostatic waves.
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Fujihiro Hamba
1989 年 58 巻 7 号 p.
2414-2422
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
A numerical simulation of reversed field pinches is performed using a three-dimensional incompressible magnetohydrodynamic (MHD) code. A turbulence model called large eddy simulation is applied. Although field reversal is obtained in a simulation without the model, the skin current inconsistent with experiment is observed near the wall. The skin current vanishes and deeper field reversal is obtained by the use of the model. The balance of terms in the mean magnetic field equation is investigated to confirm the effect of the model. The magnetic energy and its spectrum are also presented to examine the character of magnetic fluctuations.
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Akira Kato, Masahiro Wakatani
1989 年 58 巻 7 号 p.
2423-2429
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Velocity space loss regions are studied by using constants of motion to calculate particle orbits in
l=2 torsatrons. A criterion to confine a particle with
v⁄⁄\simeq0 initially is obtained in terms of ε
t(
a), ε
h(
a) and ρ
0, where
v⁄⁄ is a parallel velocity, ε
t(
a) and ε
h(
a) are magnitudes of toroidal magnetic ripple and helical magnetic ripple, respectively, and ρ
0 is a normalized radius of initial position. In order to confine all particles in ρ
0≤0.3, ε
h(
a)⁄ε
t(
a)≥3–3.5 is required for a model magnetic field described by both ε
t(
r) and ε
h(
r); however, ε
h(
a)⁄ε
t(
a) can be reduced to about 2 by improving particle confinement with appropriate side-band components corresponding to
l=1 and
l=3 helical fields having the same helical period number as the
l=2 helical field. This result increases flexibility for designing a low aspect ratio helical system with good confinement of high energy particles.
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Masaharu Tokunaga, Katsuhiko Fujii, Takeo Matsubara
1989 年 58 巻 7 号 p.
2430-2433
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
In some substances so called quantum paraelectrics, the structural phase transition is suppressed by the zero point vibration near
T=0. This phenomena is studied by making use of the self-consistent phonon theory. From the numerical computation on the dependence of the soft mode frequency on temperature, anisotropic polarization fluctuations due to the electrostatic interaction is found to release the suppression of the transition by the quantum effect. It is shown that the transition temperature depends not only upon the magnitude of the quantum effect but also upon the magnitude of the electrostatic interaction.
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Toyonori Munakata
1989 年 58 巻 7 号 p.
2434-2438
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
A dynamical version of the density functional theory (DFT) for classical (equilibrium) statistical mechanics is presented. A nonlinear Langevin equation with multiplicative noise is derived for a density field. The corresponding Fokker-Planck equation is shown to have the appropriate stationary distribution expressed in terms of the free energy functional.
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Norikazu Ishimura, Takao Yamamoto
1989 年 58 巻 7 号 p.
2439-2449
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
We propose a phenomenological lattice gas model to investigate an adsorbed system with strong interaction between adatoms and the substrate. In our model, adatoms sit on top of substrate atoms of the square lattice and adsorption induces surface reconstructions. The ground state of this system is discussed and is shown to have many commensurate phases of obliquely striped structure of adatoms. It is shown that these structures are caused by the long range effective adatom-adatom interaction mediated by the displacements of substrate atoms. A complex ground state phase diagram is also given.
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Yoshiyuki Ono, Kaoru Iwano, Akira Terai, Yasushi Ohfuti, Yasushi Wada
1989 年 58 巻 7 号 p.
2450-2462
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
Effects of impurities in polyacetylene are investigated numerically by using Su-Schrieffer-Heeger’s model with short-ranged site-type impurities. Particular emphases are on the infrared activities. The change of the total electron number, due to impurity doping, is compensated by introducing the same numbers of positive and negative dopants. Soliton formation and its pinning due to the impurities are confirmed. The amplitude oscillation mode, localized around a soliton, is found to have a possibility to become infrared active, though it is not active without impurities.
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Masashi Suezawa, Koji Sumino
1989 年 58 巻 7 号 p.
2463-2471
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
Properties of Si–K1 centers induced in silicon crystals by plastic deformation are investigated by means of electron spin resonance (ESR). A Si–K1 center is found to be ESR-active in its electrically neutral state. Some fraction of Si–K1 centers act as donors in
p-type Si and as acceptors in
n-type Si while the other remain to be neutral. This fact is interpreted with an idea that deformation induces a variety of electrically active centers including Si–K1 centers in a silicon crystal and electrostatic interaction between a K1 center and other centers affects the occupation of the K1 center by an electron or by a hole. The response of the ESR absorption to light illumination shows a transient behavior with respect to the illumination time. The electronic energy levels of a Si–K1 center in its charged and neutral states are determined from the analysis of photo-ESR data.
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Kaoru Kimura, Hiroki Iwahashi, Tatsuo Hashimoto, Shin Takeuchi, Uichir ...
1989 年 58 巻 7 号 p.
2472-2481
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The low-temperature specific heat (1.5 K to 6 K), the electrical resistivity (1 K to room temperature) and the magnetoresistance at 1.4, 4.2 and 10 K have been measured for the single-grained I-phase of Al–Li–Cu with near 6:4:1 composition grown by the Bridgman method. An etching method, which allows us to dissolve only the fcc Al second phase completely, was developed. The density of states at the Fermi energy obtained from the electronic specific heat coefficient is extremely small compared with the corresponding free-electron value. The resistivity at 4.2 K is as high as 870 μΩcm and decreases as −\sqrt
T below 20 K and as −
T above 20 K, indicating the development of the weak localization of electrons. Magnetic field dependence of the magnetoresistance is consistent with the theory of the localization without involving electron-electron interaction.
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Tomi Ohtsuki, Yoshiyuki Ono
1989 年 58 巻 7 号 p.
2482-2494
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Using the linear response theory, the Hall current distributions in the quantum Hall regime are calculated numerically for two dimensional systems of non- interacting electrons, confined to an area of a finite width. At the low filling factor region, the local current density is enhanced around the localized states. Such current density is much stronger than that in the impurity-free case, although the Hall conductivity, which is obtained by integrating the current density over the system, is much smaller than that in the impurity-free case. With the increase of the filling factor, the local enhancement spreads over the whole system. The current, however, flows uniformly almost in the same way as in the impurity-free case, when the Fermi level is in the bulk band gap, i.e., in the edge state region. It shows that the strong spatial fluctuations of the Hall current are locally compensated.
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Hironobu Fujii, Hirofumi Kawanaka, Toshiro Takabatake, Makio Kurisu, Y ...
1989 年 58 巻 7 号 p.
2495-2500
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
Measurements of magnetic susceptibility, electrical resistivity, thermoelectric power and thermal expansion have been performed on the half-metallic magnet UNiSn. A second-order transition from a paramagnetic semiconductor to an antiferromagnetic metal takes place at
TN=47 K without any significant lattice deformation. Unlike in the usual antiferromagnets, the curve of magnetic susceptibility sharply turns up at
TN. Magnetic fields up to 13.5 T have no significant influence either on
TN or the semiconducting energy gap. On the contrary, hydrostatic pressure increases
TN at a rate of d
TN⁄d
p=0.50 K/kbar, but suppresses the gap energy at a rate of d
Eg⁄d
p=−0.6 meV/ kbar. Thermoelectric power has an extremely sharp peak at 42 K, which is 5 K lower than
TN.
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Hiroyuki Mori, Tatsuya Nagao, Fumiko Yonezawa
1989 年 58 巻 7 号 p.
2501-2514
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
On the basis of the phenomenological model due to Lawrence and Doniach for layered superconductors, we derive a formalism for the critical temperature
Tc in relation with the numbers of layers. We show that the critical temperature
Tc of a system composed of
n identical layers is the same as that of each layer, irrespective of the number
n. We also apply our formalism to a binary periodic layered structure whose unit cell consists of two kinds of superconducting layers. When the carrier number of each layer is independent of structure, the critical temperature
Tc of the whole system increases monotonically with the number of layers having higher
Tc. When the carrier number depends on structure,
Tc does not necessarily show a monotonic behaviour. We discuss our numerical results in comparison with the experimental data on some high-
Tc superconductors such as thallium and bismuth families. We make a suggestion to achieve a higher
Tc.
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Yoshikazu Endo, Takeji Ayukawa
1989 年 58 巻 7 号 p.
2515-2520
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
A ferromagnetic thin film with single-ion uniaxial surface anisotropy is studied using Green’s function technique for the whole range of anisotropy strength. Allowing that the surface anisotropy on both sides of the film is different in strength, the layer magnetization and the Curie temperature are calculated as a function of the anisotropy of the substrate side by fixing the free-surface anisotropy at a strong or weak value. The results show that, for the case with strong free-surface anisotropy, the thermodynamic behavior of the film is driven by the free-surface, while for the case with weak anisotropy on both sides, it is mainly determined by inner layers.
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Keiichi Ohara, Kei Yosida
1989 年 58 巻 7 号 p.
2521-2530
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
A modified spin-wave theory is developed for the square-lattice antiferromagnet under the constraint that the sublattice magnetization vanishes. This constraint gives rise to a highly anisotropic susceptibility. The rotationally averaged susceptibility increases linear in temperature from its
T=0 value which is equal to the average susceptibility at
T=0, 2/3 χ
⊥, obtained by the usual spin-wave theory. The free energy and specific heat remain essentially unchanged from those obtained by the usual spin-wave theory.
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Hikomitsu Kikuchi, Yoshitami Ajiro
1989 年 58 巻 7 号 p.
2531-2546
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
ESR study is performed to elucidate crucial roles of characteristic domain-wall solitons in the title substance. The ESR signal due to Co
2+ spins at propagating domain-walls which we term the soliton signal exhibits the temperature-dependent linewidth proportional to exp (−|
J|⁄
kT), evidencing the collisional effect of the thermally excited solitons in the frustrated chains. A small amount of Mn impurities weakens the soliton signal very effectively without giving any change in the line width. A single hyperfine-structured signal due to the doped Mn
2+ spins is also observed, presenting rich information concerning the unusual spin dynamics of the host system. An additional sharp signal is newly observed in the pure and doped samples. Its behavior is very similar to that of the soliton signal. The origin of the sharp signal, however, is still unclear.
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Tatsuya Kishi, Kenn Kubo
1989 年 58 巻 7 号 p.
2547-2552
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
The existence of long range order (LRO) is examined in the antiferromagnetic Heisenberg model on the square or the simple cubic lattice with the next nearest neighbor interactions which are taken to be λ times the nearest neighbor ones (λ≥0). It is rigorously shown that Néel LRO exists at a low temperature on the simple cubic lattice and in the ground state on the square lattice for λ smaller than a critical value λ
c. On the square lattice λ
c increases with
S starting from 0.072 for
S=1 and approaches 0.5 in the limit
S→∞. On the simple cubic lattice λ
c=0.002 for
S=1⁄2 and approaches 0.25 in the limit
S→∞.
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Tadashi Tokuhiro, Sherman Susman, Torben O. Brun, Kenneth J. Volin
1989 年 58 巻 7 号 p.
2553-2569
発行日: 1989/07/15
公開日: 2007/06/01
ジャーナル
認証あり
NMR measurements have been carried out on stoichiometric β-LiAl samples as a function of temperature and frequency. The
7Li spin-lattice relaxation was found to be predominantly dipolar. Data were analyzed using several diffusion models. The results show that a fraction of the constitutional Li vacancies in β-LiAl is bound to the vicinity of a Li antisite defect. The remaining free vacancies are responsible for the fact that LiAl is a superionic Li conductor. The spin-spin relaxation results support this picture of two different vacancy environments. The high-temperature results demonstrate still another type of Li diffusion related to thermally-generated defects.
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Teruyoshi Awano, Takao Nanba, Mikihiko Ikezawa, Tomochika Matsuyama, H ...
1989 年 58 巻 7 号 p.
2570-2577
発行日: 1989/07/15
公開日: 2007/05/29
ジャーナル
認証あり
γ-ray irradiation at 77 K induces defects in Rb
2AgI
3 and K
2AgI
3 crystals. The analysis of hyperfine structure and super-hyperfine structure of ESR spectra shows that a hole is self-trapped mainly at an iodine ion and is weakly coupled to the nearest alkali ion of Rb
+ or K
+. The center has a symmetry axis along the direction from the iodine ion to the alkali ion. Iodine ions at two sites, out of three different sites in the unit cell, form the hole center. The optical absorption spectra measured with the linearly polarized light along the
a-,
b- and
c-axis of the crystal of Rb
2AgI
3 have main peaks at about 2.9, 2.5 and 3.2 eV, respectively. The respective peaks in K
2AgI
3 crystal are at about 2.9, 2.5 and 3.1 eV.
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