-
Sadayoshi Toh
1995 Volume 64 Issue 3 Pages
685-689
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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To understand how entropy (T
2/2) is cascaded to smaller scales and kinetic energy is transferred to larger scales, temporal evolutions of the entropies and the energies distributed into several scales by 2D wavelet are examined numerically. The correlation coefficient of entropy between adjacent scales has a sharp peak and the delay time giving this peak is scaled as k
-2/5. The direction of energy transfer is not fixed but reverses occasionally between normal and inverse.
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Leonid G. Bruskin, Teruo Tamano
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1995 Volume 64 Issue 3 Pages
690-694
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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It is analytically shown that interaction of magnetized multicomponent plasma with a target surface causes an instability of material erosion. The wave numbers and increments of growing fluctuations are determined in a linear approximation. The mean time of surface roughening is of the same order or even shorter than that of the erosion process itself. Erosion instabilities are of importance for long-pulse or steady-state operation of future reactor-grade fusion devices.
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Tota Nakamura, Yohei Saika
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 3 Pages
695-698
Published: March 01, 1995
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A one-dimensional fully frustrated quantum spin system called the Δ-chain is investigated, particularly with respect to the low-temperature structure of the specific heat, by quantum Monte Carlo simulations using the restructuring method. Sizes of the systems we considered are N=32, 48 and 64. The simulation results together with the diagonalization results for N=10 and 16 show that the size dependence of the data is very weak, and thus the second peak of the specific heat stably exists at T<0.1, which corresponds to less than half the spin gap. Locality of excitations is seen in the Monte Carlo snapshot. We consider that the low-temperature properties of this system are governed by the local elementary excitations which generate the Schottky-type specific heat peak in the background of the ordinary thermal specific heat.
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Kaoru Mizuno, Kotaro Ono, Kazuyoshi Ito, Takao Kino
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 3 Pages
699-701
Published: March 01, 1995
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In order to investigate interstitial-type dislocation loops grown as vacancy sources after a temperature rise in nearly perfect aluminum crystals, a single-scanned X-ray Lang topograph was taken while a specimen crystal was cooled to room temperature from 295°C at a cooling rate of 1000°C/h in air. The interstitial loops were found to be frozen in the crystal without multiplication of glide dislocations and few loops disappeared upon cooling.
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Ryousuke Shiina
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
702-705
Published: March 01, 1995
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The effects of doped impurities of heavy fermion semiconductors are studied on the basis of the periodic Anderson model with randomly distributed Kondo holes. The slave boson mean-field theory is applied to treat the strong Coulomb interaction on f-orbitals, while the effect of disorder is analyzed by the coherent potential approximation (CPA). It is shown that the low-temperature behaviors of specific heat and resistivity are strongly affected by a small amount of impurities due to the formation of an impurity band in the hybridization gap. The results are compared with the experimental observation in the doped heavy fermion semiconductor (Ce
1-xLa
x)
3Bi
4Pt
3.
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Shu–ichi Izawa, Shingo Katsumoto, Akira Endo, Yasuhiro Iye
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
706-710
Published: March 01, 1995
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We have observed an oscillatory magnetoresistance effect in a two-dimensional electron gas in GaAs/AlGaAs heterojunctions subjected to a periodically modulated magnetic field generated using a striped gate electrode of ferromagnetic metal. The hysteretic part of magnetoresistance clearly shows oscillations analogous to the so-called Weiss oscillation with the phase relation predicted for the case of vector potential modulation.
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Hikaru Kawamura
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
711-715
Published: March 01, 1995
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A close connection is pointed out between the orbital-glass state recently proposed for high-T
c ceramic superconductors and the chiral-glass state identified in XY spin glasses. Based on this analogy, the orbital-glass state is argued to be an equilibrium phase with broken reflection (charge-conjugation) symmetry, but not a true superconductor on long length and time scales. The transition to the normal state lies in the universality class of the 3d Ising spin glass. It is predicted that the nonlinear susceptibility in the zero-field limit exhibits a negative divergence for d-wave ceramics and a positive divergence for s-wave ceramics.
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Kenji Nakamura, Yasuo Endoh, Kazuyoshi Yamada, Shyoichi Hosoya, Nobuhi ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
716-720
Published: March 01, 1995
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Quasielastic neutron scattering experiments from La
2NiO
4+δ revealed a substantial hole doping effect on the 2 dimensional spin correlations. Thermal evolution of correlation length clearly shows the reduction of the exchange stiffness constant by hole doping, which is in marked contrast to that of La
2CuO
4+δ. The present result is reflected by the hole character in La
2NiO
4+δ, which is different from that in the cuprate.
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Masahiro Matsumura, Yoichi Sakamoto, Tomotaka Fushihara, Yutaka Itoh, ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
721-724
Published: March 01, 1995
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In order to investigate the hole doping dependence of the spin-gap behavior in Y123 system, the temperature dependence of the nuclear spin-lattice relaxation time T
1 of Cu(2) site was measured in Y(Ba
1-xLa
x)
2Cu
3O
y system. The long-range antiferromagnetic ordered states in x≥0.4 confirmed by the Cu(2) NMR signal around 90, MHz ensure that the system is in the lightly doped region, at least in x\le0.3. Well-defined spin-gap behaviors were observed at least in x\le0.1. Considering the previous result for YBa
2Cu
3O
6.63, the spin-gap temperature, T
s, which is defined as the peak temperature in (T
1T)
-1(T), increases linearly with the decrease of the hole content per unit cell in CuO
2 sheet, P
sh(x), which was evaluated on the basis of the diagram by Tokura et al. and our results for oxygen content y. This result places one restriction on the theoretical model for the spin-gap behavior.
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Hideki Tou, Yoshio Kitaoka, Kunisuke Asayama, Christoph Geibel, Christ ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
725-729
Published: March 01, 1995
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The nuclear-spin-lattice relaxation rate,
27(1/T
1), of the high-quality polycrystalline UPd
2Al
3 with a record T
c=2, K and the narrowest Al NQR linewidth to date of 12, kHz has been measured in zero magnetic field by the NQR technique.
27(1/T
1) below T
c has been found to obey the T
3-law at least down to 0.18, K, giving strong evidence that the energy gap vanishes along lines on the Fermi surface. From the analysis of
27Al Knight shift below T
c, it is shown that the anisotropic residual Knight shift originates from the f-electron susceptibility in the antiferromagnetic state, whereas the isotropic reduction of the shift below T
c is due to a singlet pairing nature of the superconductivity. Both the results of
27(1/T
1) and
27Al Knight shift in UPd
2Al
3 can be reproduced consistently by a d-wave pairing model characterized by lines of vanishing gap on the Fermi surface.
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Shuichi Nakamura, Tetsuji Konishi, Akihiko Kitada
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 3 Pages
731-735
Published: March 01, 1995
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We topologize a polycrystal composed of single crystals defined in a finite-dimensional affine space, to be a complete metric space. In the topological space “polycrystal”, we can find a compact domain with a self-similarity which is one of the geometrical properties characteristic of the complete metric space.
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Noriko Akutsu, Yasuhiro Akutsu
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 3 Pages
736-756
Published: March 01, 1995
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For two-dimensional (2D) lattice gas which consists of more than one sublattices, we show that microscopic interface energy cannot be determined uniquely. Accordingly, the interface tension has unavoidable ambiguity in choice of the origin (Wulff point) of the Wulff plot. On the other hand, interface stiffness, equilibrium crystal shape and interface entropy are free from the ambiguity. For anisotropic systems, it has been known that the interface tension in various “physical” formulas is replaced by the interface stiffness, which can be naturally understood from the ambiguity argument. As a demonstration, we consider a step (regarded as a 1D interface) on the (10\overline{1}0) surface of the hexagonal ZnS-type crystal, and calculate interface (step) quantities at finite temperatures. Critical curve is successfully obtained from zeros of the interface stiffness.
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Sumiyoshi Fujiki, Nahomi M. Fujiki
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 3 Pages
757-765
Published: March 01, 1995
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A positive reinforcement type learning algorithm is formulated for a stochastic feed-forward neural network by minimizing a relative entropic measure, and a learning equation similar to that of the Boltzmann machine is obtained. The learning of the network actually shows a similar result to that of the Boltzmann machine in the classification problems of AND and XOR, by numerical experiments.
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Schin Daté, Kenji Kumagai, Osamu Miyamura, Hiroyuki Sumiyoshi, ...
Subject area: General theory of fields and particles.
1995 Volume 64 Issue 3 Pages
766-776
Published: March 01, 1995
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Local collision frequencies of produced hadrons in ultrarelativistic nucleus-nucleus collisions are studied by an event generator URASiMA. From these frequencies, local number densities of produced hadrons are derived. It turns out that thermalized high density local system is achievable in CERN-SPS energy region although its size is not always large. Time evolution and nuclear mass number dependence of these quantities, frequency and density, are also investigated.
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Jirohta Kasagi, Tsutomu Ohtsuki, Keizo Ishii, Masayuki Hiraga
Subject area: Nuclear structure.
1995 Volume 64 Issue 3 Pages
777-783
Published: March 01, 1995
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Energetic charged particles have been measured in the bombardment of 150-keV deuterons on deuterated Ti. Protons and α particles were observed with energies up to --17 and --6.5, MeV, respectively, which can never be attained in the D+D reaction. A bump structure at around 14, MeV seen in the proton spectrum can be well explained as emitted in the sequential reaction involving three deuterons. However, protons and α particles distributed continuously up to the maximum energies can never be understood as products of the conceivable nuclear reactions.
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Bhaben Chandra Kalita, Satyendra Nath Barman
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1995 Volume 64 Issue 3 Pages
784-790
Published: March 01, 1995
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Ion-acoustic soliton in a warm plasma with positive and negative ions of equal temperatures is studied under the influence of electron inertia. Depending upon Q (=m
j/m
i, negative ion to positive ion mass ratio) and various ion temperatures, compressive fast ion-acoustic solitons for Q>1, and both compressive and rarefactive fast ion-acoustic solitons for Q<1 are shown to exist.
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Arimichi Takayama, Masahiro Wakatani, Hideo Sugama
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1995 Volume 64 Issue 3 Pages
791-799
Published: March 01, 1995
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Nonlinear evolution of two dimensional pressure-driven interchange mode produces relaxation oscillations in the presence of poloidal shear flow for Reyleigh number Ra--10
4. Here the flow velocity has a symmetric profile with respect to the center of slab plasma where the velocity shear disappears. There is a tendency that the velocity shear becomes weak after the saturatioin. When the velocity shear almost disappears, fluctuations grow rapidly. Then the velocity shear is again generated to suppress the growth of fluctuations. This kind of relaxation oscillation may be related to ELM [Edge Localized Mode] in the H-mode of tokamak.
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Marcus Hacke, Eiichi Yagi
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 3 Pages
800-808
Published: March 01, 1995
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The behaviour of Kr atoms implanted into aluminium at room temperature with a dose of 1×10
15, Kr/cm
2 has been investigated by a channelling method for isochronal annealing up to 683, K. In the as-implanted state the Kr atoms are distributed over tetrahedral (T), octahedral (O), substitutional (S) and random (R) sites. On annealing at 433 and 593, K, the T- and O-site occupancies disappear, respectively, and in both cases the fraction of the S-site occupancy decreases and that of the R-site occupancy increases. The T- and O-site occupancies have been interpreted to be a result of the formation of Kr-vacancy (V) complexes of KrV
4 and KrV
6, respectively, and the R-site occupancy to be Kr atoms associated with cavities. Therefore, the annealing stages at 433 and 593, K are explained in terms of the dissociation of KrV
4 and KrV
6, respectively. On annealing at 683, K, solid krypton is formed.
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Masanori Aoki, Shozo Takeno
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 3 Pages
809-821
Published: March 01, 1995
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Numerical experiments and a theoretical study are made for the diatomic Toda lattice equation to show the existence of stationary nonlinear gap modes. The characteristic properties of the nonlinear localized mode obtained numerically and analytically using the rotating-wave approximation are: (1) It arises from the soft anharmonicity of an effective potential for the Toda lattice. (2) Its central position is located at the site of a lighter atom. (3) Its eigenfrequency is splitted from the bottom of the optic frequency band. (4) The gap mode profile is composed of two parts, a localized s-like vibrational mode and a lattice distortion. (5) For not too large anharmonicity, there exists a simple relationship between a shift function and an envelope function representing the lattice distortion and the vibrational amplitude, respectively.
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Hisashi Haga, Akira Onodera, Yoichi Shiozaki, Kenji Ema, Hideaki Sakat ...
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 3 Pages
822-829
Published: March 01, 1995
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A high-resolution heat capacity measurement has been carried out near the normal-incommensurate phase transition in Rb
2ZnCl
4 by an ac calorimeter. The obtained data have been analyzed with a renormalization-group expression which includes correction terms up to the second order. It was found that the heat capacity anomaly is described well with the three dimensional XY model; the critical exponent, the critical amplitude ratio, and the universal constant derived from the first-order correction amplitude agree well with the theoretically expected values.
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Masahiko Higuchi, Akira Hasegawa
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
830-847
Published: March 01, 1995
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In order to derive an efficient method for calculating the electronic structures including the f bands in the rare-earth and the actinide compounds with complex crystal structures, Loucks' relativistic augmented-plane-wave method is converted into a linear form by relativistic band theory proposed by Takeda. In this method, the four-component relativistic plane wave is augmented by a linear combination of the solutions of the Dirac equation for two fixed energies for each angular momentum, and the secular equation is derived directly from the Dirac Hamiltonian. As an application of this linear method, the electronic structure is calculated for the double-hexagonal rare-earth compound YbGa
2. A self-consistent calculation reveals that the f bands lie just below the Fermi level and that the Fermi surface consists of small hole and electron sheets, which can explain experimental results for the de Haas-van Alphen effect reasonably well.
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Chikara Sugiura
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
848-857
Published: March 01, 1995
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With a high-resolution two-crystal vacuum spectrometer, the phosphorus Kβ emission spectra in fluorescence are measured for H
3PO_{3 (= H
2PHO
3)}, H
3PO
4, Li
3PO
4, Na
3PO
4· 12H
2O, Na
2HPO
4, NaH
2PO
4, K
3PO
4· nH
2O, K
2HPO
4, KH
2PO
4, Ca
3(PO
4)
2, CaHPO
4· 2H
2O, Ca(H
2PO
4)
2· H
2O, CaHPO
3· H
2O, Ca(H
2PO
2)
2 and NH
4H
2PO
4. In the phosphate compounds, a weak peak is observed on the high-energy side of the main peak Kβ
1 and related to a molecular orbital of t
2 symmetry in the PO
43-ion. It is shown that the phosphorus Kβ emission spectra are influenced by ligand substitution and cations. The measured Kβ emission spectra of Li
3PO
4, Na
3PO
4· 12H
2O, K
3PO
4· nH
2O and Ca
3(PO
4)
2 are presented along with the previously reported P-K absorption spectra of these phosphate compounds. The emission and absorption spectra are interpreted in terms of available molecular orbitals of the PO
43- ion.
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Shuichi Ishida, Kazuo Murase, Kenji Gamo, Susumu Namba
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
858-871
Published: March 01, 1995
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The low-temperature magnetoresistance (MR) of PtSi thin films and narrow wires with 6, nm thickness has been studied to determine the physical parameters in the weak localization with strong spin-orbit interaction, including superconducting fluctuations. We find the magnetic scattering to be negligible in the thin films. For the wires, the obtained magnetic scattering time τ
s is found to decrease with narrowing wire width. This is interpreted as the spin effect due to sidewall damage caused by ion-beam etching. The reduction in T
c with narrowing width has also been deduced, which is qualitatively explained both by the increase of localization which enhances the Coulomb interaction and by the increased magnetic scattering which destroys Cooper pairs.
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B. Roy, S. Roy, D. Chakravorty, H. Jain
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
872-876
Published: March 01, 1995
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The resistivity of metallic particles of silver and copper respectively having diameters in the range 4.2 to 11.4, nm and grown within a glass-ceramic has been measured over the temperature range 5 to 300, K. The resistivity vs. temperature curve shows a dip at a temperature in the range 40 to 60, K the exact temperature depending on the metal particle diameter. The resistivity data have been fitted to Ziman equation and the effective Debye temperature θ
D as estimated shows a minimum value corresponding to a metal particle diameter around 6, nm for both the metallic species. This is explained as arising due to the occurrence of at least two fractal dimensions in the structure of the percolative chains of the metal particles.
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Tsuyoshi Ueta
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
877-886
Published: March 01, 1995
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The time evolution of a Gaussian wave packet of an electron, which is confined in a quantum dot subjected to uniform magnetic fields, is analytically studied in terms of the exact Feynman kernel. The central position of the wave packet follows the classical trajectory. Although the motion of the central position is aperiodic due to its dual period, the variance of the probability density changes periodically. If the shape of the initial wave packet is the same as that of the wave function of the ground state, its shape never alters. For more general systems in which the periodic full revival of electron wave packets is realized, the characteristic of energy eigenvalues is discussed.
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Yoji Ohashi
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
887-912
Published: March 01, 1995
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A new experimental method to judge the symmetry of the order parameter in high-T
c superconductivity is proposed. The interference of reflected holes from different directions due to the Andreev reflection causes quite different phenomena among s-, d
x2{-y}
2- and d
xy-wave superconductivity. It is shown that this interference effect may be observed as a change of the conductance below T
c, which enables us to identify the symmetry of the pairing state in high-T
c superconductivity. Various cases in which the experimental setup deviates from the ideal situation are also studied and experimental condition for this method is clarified.
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M. E. Zhitomirsky
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
913-921
Published: March 01, 1995
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Besides usual flux lines the topology of the “real” vector phase in a multicomponent superconductor admits an existence of half-quantum vortices in the bulk. These vortices have a divergent energy near H
c1. However, the possibility of their existence reveals itself in an instability of a usual singular one-quantum vortex towards dissociation into the nonsingular bound pair of half-quantum vortices. Considering an example of the multicomponent Ginzburg-Landau functional we found analytically critical values of phenomenological parameters corresponding to this instability, as well as the symmetry group of the vortex pair.
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Hiroki Tsuchiura, Yukio Tanaka, Yasunari Ushijima
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
922-926
Published: March 01, 1995
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Coexistence of the s and d
x2-y2-wave (d-wave) pairing is investigated in the two-dimensional (2-D) extended Hubbard model with on-site repulsive and inter-site attractive interactions using the mean-field approximation at T=0, K. The next-nearest-neighbor hopping effect can induce the coexistence of the s and d-wave pairing. It is found that in such a case, s+id-wave pairing state becomes most stable.
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Shinichi Itoh, Hironobu Ikeda, Daisuke Sugimoto, Kazuaki Iwasa, Roger ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
927-933
Published: March 01, 1995
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Neutron inelastic-scattering experiments on an Ising-like quantum antiferromagnetic chain with nonmagnetic impurities, CsCo
cMg
1-cCl
3 (c=1, 0.95, 0.9, 0.85, 0.6 and 0.4), were performed. The concentration dependence of the spin dynamics showed that although the solitons and the spin-wave continuum state were stable for a small amount of nonmagnetic impurities, they vanished at c=0.8. We also observed the coexistence of Ising-cluster excitations and intra-cluster excitations at low temperatures. These results can be well interpreted by a theory incorporated with next-nearest-neighbor interactions in the chain.
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Serng–Yerl Park, Sadatsugu Muto, Akio Kimura, Shin Imada, Yasush ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
934-943
Published: March 01, 1995
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The magnetic circular dichroism of Ni
xPd
1-x was measured in the Ni 3p, Pd 4p, Ni 2p, and Pd 3p excitation region. The change in the total magnetic moment and the contribution by orbital moments associated with the constituent atoms were estimated through the obtained spectra. There is a non negligible difference between the data in the Ni 3p-3d excitation region and those in the Ni 2p-3d excitation region, which has been interpreted in terms of atomic and itinerant aspects of the 3d states. It is found that the Ni 2p-3d spectra reflects atomic aspect of the valence band while Ni 3p-3d spectra an itinerant aspect, both of which give complementary information. The orbital moment is found to increase with decreasing x. The result is not in full agreement with the previous result of the band calculation.
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Sanshiro Sako, Kazunari Ohshima
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
944-950
Published: March 01, 1995
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The size dependence of Néel temperature T
N of MnO ultrafine particles in LiF matrix with the average size range from 4.0, nm to 5.4, nm was investigated through the temperature dependence of the ESR linewidth. It was found that the T
N of MnO ultrafine particles becomes smaller than that in bulk state, and decreases as the size becomes smaller. The fact is mainly attributed to the smallness of the coordination number of surface atom in a particle. This tendency is also confirmed by the calculation of using mean field approximation of the Ising clusters.
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Takashi Shirane, Tomohiro Moriya, Teruo Bitoh, Akira Sawada, Hiroyuki ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
951-959
Published: March 01, 1995
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The ac linear (χ
0) and nonlinear (χ
2) susceptibilities of a ferromagnetic Ni have been studied near the Curie temperature, to clarify the feature of the magnetic phase transition. The first observation for the critical behavior of χ
2 in a pure ferromagnetic system has been made at low frequency measurement. The observed χ
2 at higher frequencies is affected extremely by the contribution of the eddy currents. From analysis of the frequency dependence of χ
0 and χ
2, the method of eddy-current correction for χ
2 is found. Analysis of the critical behavior of χ
0 and χ
2 yields the critical exponents γ =1.333± 0.008 and γ
2=4.69± 0.30.
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Tohru Moriya, Tetsuya Takimoto
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
960-969
Published: March 01, 1995
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Spin fluctuations in heavy electron systems around their antiferromagnetic instability are discussed from a phenomenological point of view by using a sum rule for the dynamical susceptibility valid in the strong correlation limit. As a result the dynamical susceptibility takes the same form as in the standard spin fluctuation theory of weak itinerant antiferromagnetism, although the values for the parameters are substantially different from those in d-metals. The expression for the Néel temperature given in terms of the staggered magnetization at 0, K and the spin fluctuation parameters are successfully compared with experiment. Anomalous (non-Fermi liquid) behaviors reported for the specific heat and electrical resistivity in some heavy electron systems around their magnetic instabilities are explained in terms of this theory.
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Masayuki Itoh, Ikuomi Natori
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
970-975
Published: March 01, 1995
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59Co and
139La NMR measurements have been made to reveal microscopically the hole-doping effect on the spin state and magnetic properties of La
1-xSr
xCoO
3 (0{\le}x{\le}0.5). The signal from the Co atoms with no Sr nearest neighbors was observed in the spin-glass region below x
c--0.18. From the analysis of the temperature dependence of the Knight shift, the ground state of such Co atoms was found to be the trivalent low-spin state
1A
1g. Above x
c, we observed at 4.2, K the
59Co and
139La signals which come from the cluster-glass region with a finite ferromagnetic correlation. Thus, it was microscopically confirmed that the boundary between the two regions is located at x
c--0.18.
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Hiroshi Orihara, Akihiro Fukase, Yoshihiro Ishibashi
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
976-980
Published: March 01, 1995
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The nonlinear dielectric spectroscopy of the Goldstone mode has been performed in a ferroelectric liquid crystal. The third-order dielectric constant obtained from the experiments was analyzed in terms of a formula derived from a phenomenological equation of motion by Orihara and Ishibashi [J. Phys. Soc. Jpn. 62 (1993) 489]. The dispersion and the Cole-Cole plot of the third-order dielectric constant were well reproduced by the theory, and the relaxation times obtained from the linear and the third-order dielectric constants were the same, indicating that the equation of motion is still valid in obtaining the nonlinear dielectric constants as well as the linear one. On the basis of the experimental results we discuss dynamic equations described in terms of fractional derivatives.
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Yoichiro Yagi, Katsuhiko Fujii, Hironobu Kondo
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
981-986
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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The γ-β transition in a superionic conductor Ag
3SI is studied on the basis of the order-disorder transition for Ag ions. The Ag ion, taking one of the four equivalent sites which are slightly apart from the face centered position of cube, is represented by the orientational rotator with four components. The dielectric properties are described by the ordered parameter appearing in [111] direction, and the transition temperature is estimated by assuming three kinds of the interactions: Coulomb potential between Ag ions, dipole-dipole interaction and repulsive potential between electron clouds.
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Tamao Matsumoto, Masanobu Shirai, Ken–ichi Kan"no
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 3 Pages
987-1001
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Excitation spectra for the fluorescent and phosphorescent components of type I bands in seven alkali halides, NaCl, NaBr, KBr, RbBr, NaI, KI and RbI, are measured in both energy ranges of the free exciton absorption and the band-to-band transition. Using SR pulses as the excitation light source, the two components are resolved by the method of simultaneous photon-counting through two independent time-windows. Excitation spectra for the phosphorescent bands of type II or III are also measured for comparison. From these spectra, total luminescence yield and the fraction of the type I band are determined as a function of excitation energy. On the basis of these results, the relaxation processes of free electron-hole pairs and free excitons, especially on the difference between them, are discussed.
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Masaaki Sugiyama, Yutaka Maeda
Subject area: Materials science.
1995 Volume 64 Issue 3 Pages
1002-1010
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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The structural changes in poly(vinyl alcohol) films by annealing and/or stretching were observed by means of small-angle neutron scattering. The difference in the neutron scattering length densities of crystalline regions and amorphous regions was made by incorporation of D
2O into the amorphous regions. In a raw cast film, the crystalline regions with cylindrical shape were randomly distributed. By stretching the film, the long axes of the crystalline regions were arranged to the stretch direction. On the other hand, the annealed film was separated to many domains where the crystalline regions and the amorphous regions were mutually stacked. Adding the stretch to the film in annealing, the stacking axes of the domains were aligned to the stretch direction.
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Hiroto Kikuchi, Kei Odai, Hideo Suzuki
Subject area: Materials science.
1995 Volume 64 Issue 3 Pages
1011-1022
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Based on the ZDO approximation of the LCAO-ASMO-SCF-CI theory of π-electrons, we show the methods of calculating the integrals ‹ Ψ
r | ∂ Ψ
s/∂ Θ›, ‹ Ψ
r| \
abla(d)
TG\
abla}(d)Ψ
s› and ‹ Ψ
r| \
abla(d)
TΨ
s› in the basic equation of photoisomerization which was derived in the pervious paper I with a due account of the kinetic energy of atomic cores. Here {Ψ
r} represent the transient π-electronic states of rhodopsin chromophore; Θ does the angle of photoisomerization; d is the internal displacement coordinate of the chromophore; G denotes the matrix G in Wilson's GF matrix method. It is also shown that the second and third integrals mentioned above can be reduced to the first one in a good approximation, and that the three integrals play very important roles in the photoisomerization of the chromophore.
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Masahiro Nakagawa
Subject area: Materials science.
1995 Volume 64 Issue 3 Pages
1023-1031
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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In this paper we shall propose a novel chaos neuron model with a periodic activation function and investigate the dynamic properties in a chaotic memory retrieval mode. The present artificial neuron model is characterized by a sinusoidal activation function. It is elucidated that the present neural network has an ability of the dynamic memory retrievals beyond the conventional chaotic model with such a monotonous mapping as a sigmoid function. This advantage is considered to result from the nonmonotonous property of the analogue periodic mapping which may be accompanied with a chaotic behaviour of the neurons. It is also found that the present analogue neuron model has a relatively larger memory capacity than the conventional association model even for the case of the monotonous mapping as a special case.
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V. S. R. Sasipalli, Koichi Harada
1995 Volume 64 Issue 3 Pages
1032-1033
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Shigeru Sasabe, Yuji Okunaga
1995 Volume 64 Issue 3 Pages
1034-1035
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Tetsu Yajima, Katsuhiro Nishinari
1995 Volume 64 Issue 3 Pages
1036-1037
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Youhong Wu, Shigeo Sasaki, Hiroyasu Shimizu, Mami Sakashita, Hiroshi Y ...
1995 Volume 64 Issue 3 Pages
1038-1039
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Kazumasa Miyake, Osamu Narikiyo
1995 Volume 64 Issue 3 Pages
1040-1041
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Yasuko Nishiyama, Akira Shimauchi, Nobuo Nakazawa
1995 Volume 64 Issue 3 Pages
1042-1043
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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Michio Sasanuma, Hiroyuki Senda
1995 Volume 64 Issue 3 Pages
1044-1045
Published: March 01, 1995
Released on J-STAGE: October 01, 1999
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