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Ryogo Hirota, Satoshi Tsujimoto
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 9 Pages
3125-3127
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Higher-order conserved quantities of a class of nonlinear difference-difference equations which are related to the discrete-time Toda equation are obtained using the Miura transformations.
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Yukiyasu Ozeki, Yoshihiko Nonomura
Subject area: Statistical physics and thermodynamics.
1995 Volume 64 Issue 9 Pages
3128-3131
Published: September 01, 1995
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The site-random Ising spin glass model is investigated. We find a rigorous symmetry for the SG correlation and the free energy, which provides some restrictions in the phase diagram. Using the defect energies calculated by the numerical transfer matrix method, we obtain evidence for the existence of the SG phase in the two-dimensional Ising system. We suggest that the transitions from the FM and the AF phases in the ground state in this model can be explained by the percolated-cluster picture, which is quite different from the frustration picture in the conventional ± J model.
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Hidezumi Terazawa
Subject area: Specific reactions and phenomenology.
1995 Volume 64 Issue 9 Pages
3132-3135
Published: September 01, 1995
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The ratio of the cross section for charm-quark pair production in vector-meson-dominant and single-resolved-photonic two-photon processes to that in direct-partonic ones is estimated to be as large as two so that the cross section for D
*± production recently measured by TOPAZ Collaboration at TRISTAN may be explained by these two-photon processes and may not necessarily lead to such indication of scalar-top-quark pair production as assumed by the experimentalists.
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Takemasa Shibata, Koichi Ogura
Subject area: Atomic and molecular collision processes and interactions.
1995 Volume 64 Issue 9 Pages
3136-3140
Published: September 01, 1995
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Cross sections of symmetric charge transfer are calculated for Gd
++Gd and Nd
++Nd in the ion incident energy range of 2, eV--5, keV considering that the charge transfer has two main reaction paths, which are resonant and nonresonant processes due to open 4f and 5d shells inside 6s electrons. Because a near-resonant process contributes to the reaction in Nd
++Nd collisions, the cross section for Nd is larger than that for Gd at energies above a few hundred electron volts and impact energy dependence is anomalous. Calculated cross sections are compared with the experimental data.
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Iwao Hosokawa
Subject area: Fluid dynamics.
1995 Volume 64 Issue 9 Pages
3141-3144
Published: September 01, 1995
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It is pointed out within the framework of Kolmogorov and Obukhov's refined similarity hypothesis that the 1D surrogate of energy dissipation rate in isotropic turbulence, which has been conventionally used by many experimentalists to investigate intermittency in isotropic turbulence, leads to an unrealistic prediction of the probability density function of velocity gradient. This suggests that any discussion of intermittency of turbulence based on the 1D surrogate may be of a more or less qualitative nature.
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P. K. Shukla, S. V. Vladimirov, M. Nambu
Subject area: The physics of plasmas and electric discharges.
1995 Volume 64 Issue 9 Pages
3145-3148
Published: September 01, 1995
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The resistive drift wave instability is examined in the presence of static charged dust grains. It is found that drift waves can become unstable on account of free energy stored in the equilibrium dust and ion density gradients in collisional dusty plasmas. Nonthermal resistive drift waves can cause anomalous particle transport.
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Isao Katanuma, Yasuhito Kiwamoto, Yoshinori Tatematsu, Kameo Ishii, Te ...
Subject area: The physics of plasmas and electric discharges.
1995 Volume 64 Issue 9 Pages
3149-3152
Published: September 01, 1995
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The monotonic electrostatic potential profile is found to be realized around the plug region of a tandem mirror, even if the ion drift velocity is zero at the point of potential maximum.
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Shinji Yuasa, Hideki Miyajima, Yoshichika Otani, Genta Masada, Nobuyos ...
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 9 Pages
3153-3156
Published: September 01, 1995
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The crystalline structure of FeRh
0.38Pd
0.62 alloy was examined by means of X-ray diffractometry. In this alloy, a new ferromagnetic phase was found below 265, K in the matrix body-centered tetragonal phase. The low-temperature phase has an orthorhombic structure (space group: C
mmm). The Fe atoms on 4i sites of the orthorhombic structure are displaced along the b-axis, while the Rh and Pd atoms on 4j sites are displaced along the a-axis.
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Kozo Tajiri, Naoshi Yamada, Hiroshi Orihara, Isao Takahashi, Hikaru Te ...
Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1995 Volume 64 Issue 9 Pages
3157-3159
Published: September 01, 1995
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In an antiferroelectric liquid crystal MHPOBC, it was found, by observation of the surface of the free-standing film by means of X-ray diffraction, that at the surface the SmA
2-type double layers, which produce a Bragg peak at half the angle of the fundamental reflection, develop in all the phases, SmA, SmC
*α , SmC
*, SmC
*γ and SmC
*A.
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Tadao Kasuya, Yasushi Okayama, Yoshinori Haga
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3160-3163
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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The anomalous Hall Effect in CeAs and CeP is studied critically based on the recent detailed experimental study under pressure of up to 2.6, GPa, as well as a vast amount of data on other rare-earth monopnictides and monochalcogenides. It is shown that the anomalous Hall effect is observed only in the intermediate region where the magnetic polaron liquid state becomes unstable and the transition to the valence fluctuation state begins to occur. Strong field dependence of the anomalous Hall effect is explained very well by a simple skew scattering model.
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Nobuo Furukawa
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3164-3167
Published: September 01, 1995
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Using the Kondo lattice model with classical spins in infinite dimension, conductivity in the perovskite-type 3d transition-metal oxide (La, , Sr)MnO
3 is theoretically studied. Green's functions as well as spontaneous magnetization are obtained exactly on the Bethe lattice as a function of temperature. Conductivity is calculated from the Kubo formula. Below the Curie temperature, resistivity as a function of magnetization is in good agreement with the experimental data. Anomalous behavior in the temperature dependence of the optical conductivity observed in (La, , Sr)MnO
3 is also explained.
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Daijiro Yoshioka
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3168-3171
Published: September 01, 1995
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(BEDT-TTF)
2MHg(SCN)
4[M:, K, , Rb, , Tl] shows typical two-dimensional angular dependent magnetoresistance oscillation (ADMRO) at high temperatures (T>8, K), but at lower temperatures it shows anomalously large magnetoresistance, and the ADMRO pattern changes. These low-temperature behaviors are explained as effects of a periodic potential. The present explanation is different from that by Kartsovnik et al. [J. Phys. I 3 (1993) 1187] in that reconstruction of the cylindrical Fermi surface into an open Fermi surface is not assumed. It is also predicted that if the periodic potential exists at quantizing magnetic field, where only a few Landau subbands cross the Fermi level, a resistivity peak of new origin should be observed.
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Akinobu Kanda, Shun–ichi Kobayashi
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3172-3174
Published: September 01, 1995
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We have studied the self-capacitance dependence of zero-bias resistance in two-dimensional arrays of highly resistive small tunnel junctions. Deviation from the square-root-cusp behavior is more prominent in arrays with smaller screening length. The results suggest that the finiteness of the screening length is responsible for disappearance of the charge Kosterlitz-Thouless (KT) transition in these arrays.
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Hideyuki Sato, Yuji Aoki, Hitoshi Sugawara, Tadashi Fukuhara
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3175-3178
Published: September 01, 1995
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We have measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat of single-crystal samples of Yb
3Rh
4Sn
13. Below the upper critical field, we observed an irreversible peak effect in the magnetization curves above a finite reversible field region. The phase diagram determined from the temperature dependence of magnetization curves resembles that for CeRu
2 which was proposed as a candidate for Fulde-Ferrel superconductors recently. A tricritical point was found near 6, K which differs from the onset temperature of 7.8, K.
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Kazuhiro Kuboki, Patrick A. Lee
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3179-3183
Published: September 01, 1995
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We consider a model for bilayer superconductors where an interlayer pairing amplitude Δ
⊥ coexists with intralayer pairing Δ
// of d
x2-y2 symmetry. This model is motivated by a recent photoemission experiment reporting the splitting of the nodes of the energy gap. In addition to offering a natural explanation of this observation, the model has a number of new experimental consequences. We find that the new state is accompanied by a spontaneous breaking of the tetragonal symmetry. We also find that the out-of-phase oscillation of Δ
⊥ and Δ
// gives rise to a new Raman active mode. The phase of Δ
⊥ may also become imaginary, leading to a state which breaks time reversal symmetry, which may have important implications for tunnelling experiments.
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Guo–qing Zheng, Yoshio Kitaoka, Kunisuke Asayama, Kazuyuki Hamad ...
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3184-3187
Published: September 01, 1995
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We report a
63Cu and
17O NMR study in the high-T
c superconductor Tl
2Ba
2Ca
2Cu
3O
10with T
c(max)=127, K. The results of T
1 and T
2G reveal that the characteristic energy of the antiferromagnetic spin fluctuation Γ
Q is higher than that in YBa
2Cu
3O
7, while the magnetic correlation lengths ξ do not differ much from each other. The high T
c in this compound is thus related to large Γ
Q, suggesting that the superconductivity is spin fluctuation mediated.
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Koji Obayashi, Hiroshi Orihara, Yoshihiro Ishibashi
Subject area: Dielectric properties and materials.
1995 Volume 64 Issue 9 Pages
3188-3191
Published: September 01, 1995
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The third-order nonlinear dielectric constant of an antiferroelectric liquid crystal, MHPOBC, was measured in the antiferroelectric phase (SmC
*A). The third-order dielectric relaxation due to the antiferroelectric Goldstone mode was observed, which was Debye-type. This Debye-type relaxation in the third-order dielectric response indicates that the third-order dielectric constant should be proportional to the linear susceptibility of the antiferroelectric Goldstone mode. The temperature dependence of the relaxation frequency was obtained from the third-order dielectric constant. By comparing it with that obtained by the photon correlation spectroscopy, it was found that the surface anchoring has a great influence on the helical pitch.
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Takao Yoshinaga
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 9 Pages
3193-3200
Published: September 01, 1995
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The integrability of the long and short wave interaction equation in a coupled form of the Nonlinear Schrödinger equation and the Korteweg-de Vries equation is examined by means of the Painlevé test. In particular, the cases when the reduced ordinary differential equation obtained through the traveling wave transformation has the Painlevé property are examined. As a result of this, except for the special cases, it is found that this equation does not pass the test without the imposition of restrictions. However, this test is not successful in the nearly integrable case, since the singular manifold expansion becomes non-uniformly valid. Furthermore, for the particular case, the condition that permits the Painlevé property is shown to be relaxed considerably for a finite time.
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Takeshi Fukuyama, Kiyoshi Kamimura, Songju Yu
Subject area: Mathematical methods in physics.
1995 Volume 64 Issue 9 Pages
3201-3206
Published: September 01, 1995
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We discuss an analytic proof of a conjecture (Nakamura) that solutions of Toda molecule equation give those of Ernst equation giving Tomimatsu-Sato solutions of Einstein equation. Using Pfaffian identities it is shown for Weyl solutions completely and for generic cases partially.
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Seiji Miyashita
Subject area: Classical and quantum physics: mechanics and fields.
1995 Volume 64 Issue 9 Pages
3207-3214
Published: September 01, 1995
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Time dependence of a magnetization under a time dependent magnetic field in systems with quantum fluctuations is studied by a direct numerical method. In particular, the time evolution of a system under a reversing field is investigated. Even a system has metastability, system can relax to the stable state when the field changes slowly enough. The process is found to be understood through the Landau-Zener mechanism. The change of the state from a metastable state is discussed in the light of quantum tunneling.
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Takeshi Iizuka
Subject area: Classical and quantum physics: mechanics and fields.
1995 Volume 64 Issue 9 Pages
3215-3225
Published: September 01, 1995
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Using a recently presented theory of nonlinear periodic systems, we investigate wave propagations in anharmonic periodic lattices. If the system is linearized, it has Bloch type solutions which are regarded as an extension of the monochromatic waves. It is shown that the modulations of the Bloch wave due to the nonlinearity and the dispersion obey the nonlinear Schrödinger equation. One of the important results is that envelope soliton propagates in the periodic lattices.
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Salvador Sabanal, Masahiro Nakagawa
Subject area: Measurement science, general laboratory techniques, and instrumentation systems.
1995 Volume 64 Issue 9 Pages
3226-3238
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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In this paper, we propose a new method to analyze the fractal properties of self-affine time-sequential data by expanding the well-known fractal dimension analysis to characterize the local dynamical fractal properties. Here we investigate the time dependence of the fractal dimensions of a time-sequential data, which we shall term the “Time-Dependent Fractal Dimensions” (TDFDs), and analyze its characteristics. As an example of self-affine time-sequential data, we will utilize vocal sounds. The TDFDs of Japanese vowels as well as Japanese and English words are evaluated by the recently proposed critical exponent method based on the power spectra and by the multifractal analysis. As a result, one may observe that the fractal properties of vocal sounds shows a dynamical change with respect to time and it was found out that there is a certain pattern of TDFDs for each data.
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Ramen Majumdar
Subject area: Nuclear structure.
1995 Volume 64 Issue 9 Pages
3239-3243
Published: September 01, 1995
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The proton strength distributions of the discrete hole states of
207Tl have been deduced within the framework of the Hole-Core vibrational scheme. The spectroscopic factors of the low-lying states have been compared with the recent experimental works performed with the help of energetic polarised deuteron beam. The loss of shell-model identities of these discrete proton states are explained due to strong mixing of the proton hole orbitals with the collective vibrational states of
208Pb core nucleus including the ones arising from the giant resonances.
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Tomohiko Ikuta, Akihiro Taniguchi, Hiroshi Yamamoto, Kiyoshi Kawade, Y ...
Subject area: Nuclear decay and radioactivity.
1995 Volume 64 Issue 9 Pages
3244-3254
Published: September 01, 1995
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The systematic Q
β measurements of 14 neutron-rich nuclei in the mass region from A=147 to A=152 have been performed with an HPGe detector. Neutron rich nuclei were mass separated from the thermal neutron induced fission of
235U using a He-jet type on-line isotope separator which has been developed at the Kyoto University Reactor (KUR). From β -ray singles and β -γ coincidence measurements, the Q
β values of
147La,
147-150Ce,
147-152Pr,
152Nd and
152Pm have been determined. The Q
β values of
152Pr and
152Nd have been measured for the first time. The atomic masses derived from the Q
β values are compared with the predictions of theoretical mass calculations.
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Akio Itoh, Nobutsugu Imanishi, Fumio Fukuzawa, Nariaki Hamamoto, Shin& ...
Subject area: Atomic and molecular collision processes and interactions.
1995 Volume 64 Issue 9 Pages
3255-3264
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Cross sections have been measured for single, double and triple electron capture by C
q+ (q=1--4) ions from H
2, CH
4, C
2H
6, C
3H
8 and CO
2 molecules in the energy range of (1--20)q, keV. The cross sections obtained here exhibit little dependence on the incident energy. Compared with the previous scaling laws, the present cross sections revealed a much stronger dependence on the first ionization potential of the molecules. For hydrocarbon molecules including H
2 all the cross sections show a remarkable linearity on the number of compositeatoms. The single electron capture cross sections σ
q, q-1 are compared with the classical over barrier model and with the Olson model which was slighty modified so as to be applied to the molecular targets.
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Yuichi Yamane, Yukio Kaneda, Masao Doi
Subject area: Mechanics, elasticity, and rheology.
1995 Volume 64 Issue 9 Pages
3265-3274
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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A computer simulation is carried out for the motion of many rodlike particles suspended in a Newtonian fluid subject to a shear flow. It is based on a model which takes into account the short range part of the hydrodynamic interaction between the rods only and neglect the long range part. The simulation is done for both wall bounded systems and unbounded systems. It is found that (i) the rotational motion of the rodlike particle becomes chaotic due to the hydrodynamic interaction and the Folgar-Tucker constant which characterizes the chaotic motion increases linearly with the concentration, (ii) the average period of the rotational motion increases with concentration in agreement with experiments of Stover et al., and (iii) the rods near the wall are aligned towards the vorticity.
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Takeshi Miyazaki, Toshihiro Kubo
Subject area: Fluid dynamics.
1995 Volume 64 Issue 9 Pages
3275-3283
Published: September 01, 1995
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The linear axisymmetric stability of a stretching capillary jet with parabolic axial velocity is investigated, numerically. Since the basic flow is time-dependent, the stability analysis is reduced to an initial-value problem of ordinary differential equations, instead of an eigenvalue problem for normal modes. It is shown that a parabolic velocity profile has a remarkable stabilizing effect.
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Katsuhiro Suzuki
Subject area: Fluid dynamics.
1995 Volume 64 Issue 9 Pages
3284-3290
Published: September 01, 1995
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Influence of weak dissipation on the simple waves in relativistic magnetohydrodynamic fluid (MHD fluid) is considered. By means of the method of asymptotic expansions, a relativistic analogue of MHD Burgers equation is derived. It is reduced to the non-relativistic MHD Burgers equation in the classical limit. Relativistic and magnetic effect on the thickness of the shock are examined. Dependence of the thickness on the external magnetic field is illustrated in both the classical and ultrarelativistic limit.
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Hisao Ashida, Hisaya Sugimoto, Takasi Kurasawa
Subject area: The physics of plasmas and electric discharges.
1995 Volume 64 Issue 9 Pages
3291-3299
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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The instability of the axisymmetric spherical force free plasma with the parallel plasma flow to the magnetic filed is studied by using the MHD equations under the condition of incompressibility. The linear growth rate of the unstable mode with the fixed toroidal mode number n=1 is obtained and it decreases with the increase of Alfven Mach number C
A in the rage of C
A<1 in the case of the free boundary. The nonliner numerical analysis in the free boundary case shows that the tilting mode plays a main role, and the damping rate of the original helicity and the toroidal flux decreases with the increase of C
A.
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G. P. Bahuguna, V. D. Guputa, C. Mehrotra
Subject area: Structure of liquids and solids; crystallography.
1995 Volume 64 Issue 9 Pages
3300-3308
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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The small-angle X-ray scattering (SAXS) curves on ultra-long n-alkanes obtained by Ungar and Keller at different times after reaching the crytallization temperature have been Fourier analysed and the correlation curves so obtained at different temperatures and different annealing times reflect sensitively all those morphological features which are broadly characteristic of the scattering curves. In addition the correlation curves beautifully show a transition from a non-integer-fraction (NIF) length to extended (E) chain structure. Some other parameters characterizing the kinetics of morphological features, which are not easily observable in SAXS, such as crystalline and amorphous lengths, degree of order and halfwidths of correlation peaks are also reported.
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Shigeo Sasaki, Hiroyasu Shimizu
Subject area: Mechanical and acoustical properties of condesed matter.
1995 Volume 64 Issue 9 Pages
3309-3314
Published: September 01, 1995
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Acoustic velocities, refractive index, and elastic constants in the orientationally disordered solid phase I of D
2S have been determined at pressures up to 5, GPa and room temperature, by Brillouin spectroscopy developed for a single crystal grown in a diamond anvil cell. It has turned out that H
2S and D
2S have large values of the ratio of the longitudinal acoustic velocity to the slow transverse one in the [110] direction, i.e., 3.22 and 3.30 at 1, GPa, respectively. These results indicate the molecular rotation-translation coupling is effective in the orientationally disordered phase I. These values of this ratio decrease with increasing pressure, which means that the rotation-translation coupling becomes weak with compression, resulting in stronger hydrogen bond in H
2S and D
2S.
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Hiroshi Matsui, Terutaka Goto, Mitsuo Kataoka, Takashi Suzuki, Hisatom ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 9 Pages
3315-3327
Published: September 01, 1995
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Acoustic de Haas-van Alphen (dHvA) effect of LaB
6 has been investigated by the ultrasonic velocity measurement. The oscillation intensities of the elastic constants have been found to be highly anisotropic even for magnetic field directions with crystallographic equivalence. This anisotropy depends strongly on the polarization and propagation directions of the ultrasonic modes. The observed oscillation intensities have been analyzed by means of the theory of the acoustic dHvA effect which bases on the effective mass approximation. These analyses enable us to know the change of the cross-sectional areas of the Fermi surfaces by the ultrasonic wave and therefore the electron-lattice interaction. The characteristic features of the electron-lattice interactions for the main α Fermi surfaces at X points and for the small ρ Fermi surfaces on Σ lines are presented.
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Kazuyuki Motoki, Rikio Settai, Noriaki Kimura, Hiroyuki Toshima, Takao ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 9 Pages
3328-3335
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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We have observed the de Haas-van Alphen oscillation in LaAg and CeAg. Four kinds of closed Fermi surfaces are detected in LaAg, which are in good agreement with the results of band calculations. In CeAg, each Fermi surface is split into two Fermi surfaces with the up- and down-spin states due to the ferromagnetic exchange interaction. The cyclotron mass of CeAg is not very large, which is only by 40% larger than the corresponding mass of LaAg.
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Makoto Nakaura, Tetsuya Ozawa, Kunio Saiga, Shintaro Kumazawa, Hiroyuk ...
Subject area: Electron states in condensed matter.
1995 Volume 64 Issue 9 Pages
3336-3342
Published: September 01, 1995
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Using synchrotron radiation, we carried out X-ray powder diffraction of the YBa
2Cu
3O
y compounds at the several points near the Cu K absorption edge. From the Rietveld analysis of these data, we obtained the anomalous X-ray atomic scattering factor of the Cu ions in the Cu(1) and Cu(2) sites in the superconductor (y=6.90) and the nonsuperconductor (y=6.07). In both compounds, the absorption edge of the Cu ions in the Cu(1) and Cu(2) sites is nearly equal to that of CuO. The results indicate that changes in the O content of YBa
2Cu
3O
y produce no significant changes in the valence state of Cu ions in the Cu(1) and Cu(2) sites. Detailed inspection of the spectra, however, shows that the energy position of the edge of the Cu(1) sites in the nonsuperconductor is a little lower than in the superconductor, but the magnitude of the shift is not large as that expected from monovalent Cu ion.
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Takeshi Usuki, Osamu Uemura, Tomoki Fujino, Kohei Ikeda
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3343-3351
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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The electrical conductivity, magnetic susceptibility and thermoelectric power of liquid (Tl
1/2Pb
1/2)--Te and (In
1/2Pb
1/2)--Te systems have been measured as a function of composition in the temperature range from near the melting point to 1000°C. The former system exhibits a conductivity minimum, diamagnetic maximum and change in the sign of thermoelectric power in the vicinity of 42.8 at.%Te (corresponding to the stoichiometric composition of Tl
2Pb
2Te
3). On the other hand, similar anomalies of electronic properties have been observed around 55.6 at.%Te (the stoichiometric composition of In
2Pb
2Te
5) in the latter In system. In addition, the temperature dependence of these electronic properties considerably differs in both systems, reflecting the bonding nature of Tl--Te or In--Te pair. Energy band parameters around the Fermi level at the stoichiometric composition in both systems have been determined based on the model recently developed by Enderby and Barnes (Rep. Prog. Phys. {53} (1990) 85).
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S. Sen, T. N. Misra
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3352-3359
Published: September 01, 1995
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The photoconductive properties of some carotenoid polyenes has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before the attainment of a steady state value. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperature T
max and then decrease with temperature. This behaviour has been attributed to monomolecular and bimolecular recombination processes operative at the two temperature regimes. The variation of photocurrent with light intensity provide information on the carrier generation processes. Both fast and slow decay of photocurrent have been observed at different temperatures. Temperature dependence of the decay constant and exponential trap distribution parameter T
c have been evaluated.
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Hitoshi Sugawara, Kazuyuki Motoki, Tsuyoshi Yamazaki, Takao Ebihara, N ...
Subject area: Electronic transport in condensed matter.
1995 Volume 64 Issue 9 Pages
3360-3364
Published: September 01, 1995
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We have succeeded in growing a high-quality single crystal of YbGa
2, and have done the magnetoresistance and the de Haas-van Alphen experiments. YbGa
2 is a semimetal and Fermi surfaces consist of the closed electron and hole ones. Their cyclotron masses are in the range of 0.2 to 0.9, m
0.
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Kenji Koga, Masahiko Fujita, Ken–ichi Ohshima, Yoshikazu Nishiha ...
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3365-3375
Published: September 01, 1995
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Phase separation in La
2CuO
4+δ single crystals was studied with electrical resistivity, magnetic susceptibility, X-ray and neutron diffraction measurements. The c-axis resistivity of an as-grown crystal has dropped from 265, K down to 190, K and shown a hysteretic behavior between 270, K and 190, K. From X-ray results, these anomalies have been attributed to the progress of phase separation. The antiferromagnetic transition was observed in the midst of the phase separation at 250, K using neutron and magnetic susceptibility measurements. On the other hand, the Néel point in an oxygen-reduced crystal was found to be higher than its onset of phase separation. Based on these results, an approximate phase diagram has been made. Moreover, we observed susceptibility difference between zero field and field-cooled conditions only under a low field, suggesting the magnetic-glass-like nature.
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Yasuyuki Ohyagi, Daisuke Shimada, Nobuaki Miyakawa, Akiko Mottate, Min ...
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3376-3383
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Reproducibility of phonon structures in the tunneling conductance of Bi
2Sr
2CaCu
2O
8 is discussed in relation to their positions and intensities. As for the positions, correspondences with the phonon density of states are certainly observed. As for the intensity-ratios among structures corresponding to different phonon-modes, the reproducibility is not so certain as for the positions. As for the absolute intensity, which reflects the interaction strength, the apparent reproducibility is quite poor.
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Masashige Matsumoto, Hiroyuki Shiba
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3384-3396
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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A possible coexistence of different symmetry order parameters is studied near a surface of d-wave supercoductors. The appearance of a different symmetry order parameter depends sensitively on the surface direction relative to the d-wave order parameter. In the case of d
x2-y2-wave, the (1, , 1, , 0) surface is the most favorable for coexistence. The coexisting order parameters having ± π /2 as their relative phase break locally the time-reversal symmetry near the surface.
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Satoshi Okuma, Keigo Enya, Hideaki Hirai
Subject area: Superconductivity.
1995 Volume 64 Issue 9 Pages
3397-3402
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Thickness dependence of the nonlinear resistance (I-V characteristics) has been measured in quench-condensed films of indium with thicknesses of 14, nm, 26, nm and 65, nm. The I-V curves for the 14, nm-thick film are qualitatively similar to the previous result for the much thinner film (5, nm) whose superconducting properties were well described by the two-dimensional (2D) Kosterlitz-Thouless (KT) theory. In contrast, those for the thicker films are markedly different. As I is raised from zero at low temperatures, there appears the nonlinear I-V curve (resistance) which exhibits negative curvature.
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Tetsuo Kitai
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3403-3408
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Temperature dependence of magnetic susceptibility has been studied for single crystals of rare earth intermatallic compounds TbZn
2, HoZn
2 and ErZn
2. These compounds show anisotropic and complex magnetic susceptibility below the magnetic ordering temperature. The calculations of paramagnetic susceptibility are carried out on the basis of the crystal field Hamiltonian up to second order terms taking account of molecular field. The results of calculations represent fairly well the measured paramagnetic susceptibilities of RZn
2.
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Shigeyoshi Mori, Jong–Jae Kim, Isao Harada
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3409-3415
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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We investigate the ground-state property of the one-dimensional spin-1/2 antiferromagnetic XXZ chain in a symmetry-breaking field, by means of numerical diagonalization method for finite-size spin systems combined with the phenomenological renormalization group method. It is found that, with increasing field, there occurs the ground-state phase transition from an ordered phase to a disordered phase, whose critical property belongs to the universality class of the transverse Ising model. The ground-state phase diagram is determined in two parameter regions; (i) an Ising-like region and (ii) an XY-like region. Our inspection of the field dependence of the energy gap and the static spin structure factors reveals that the ordered phase in both regions exhibits the characteristics of Néel order. Quantum nature of the ground state is also briefly discussed.
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Takao Ebihara, Rikio Settai, Noriaki Kimura, Hiroyuki Toshima, Kazuyuk ...
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3416-3421
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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We have observed the de Haas-van Alphen oscillation of the antiferromagnetic compound NdPb
3. Main Fermi surfaces consist of four closed ones, which are in good agreement with the results of band calculations based on the FLAPW method for the non-magnetic reference compound LuPb
3. The cyclotron effective masses are in the range of 0.4 m
0 to 3 m
0.
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Haruhisa Ikezawa, Rikio Settai, Masahiro Takashita, Noriaki Kimura, Ta ...
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3422-3428
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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We have measured the magnetoresistance and the de Haas-van Alphen effect of Yru
2Si
2. The Fermi surface and cyclotron mass of Yru
2Si
2 are compared to those of LaRu
2Si
2 and LaRu
2Ge
2. Main hole Fermi surfaces of the three compounds are similar and ellipsoidal in shape, which occupy about half of the Brillouin zone. The small hole Fermi surface with a shape of rugby ball is one in number for Yru
2Si
2, while three for LaRu
2Si
2 and LaRu
2Ge
2. A cylindrical Fermi surface and a multiply-connected Fermi surface exist for Yru
2Si
2, while there exists a doughnut like electron Fermi surface for LaRu
2Si
2 and LaRu
2Ge
2. The cyclotron masses of Yru
2Si
2 are about 50% and 10% larger than those of LaRu
2Si
2 and LaRu
2Ge
2, respectively.
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Hikomitsu Kikuchi, Hiroshi Nagasawa, Ko Mibu, Teruya Ono, Nobuyoshi Ho ...
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3429-3433
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Susceptibility measurements using a SQUID magnetometer on the Haldane gapped system NiC
2O
4· 2DMIz doped with nonmagnetic Zn
2+ ions in wide concentration (0≤ x≤ 0.15) were carried out. The susceptibility is composed of a bulk and a paramagnetic part induced by doping. The Curie constant C(x) of the paramagnetic susceptibility and an energy gap δ (x) concerned with the edge spins are evaluated. C(x) follws the VBS theory when x is small, whereas, for larger x, it deviates from the theory owing to the effect of the spin correlation. The correlation length ξ is evaluated to be 8.0 lattice sites from the concentration dependence of δ (x).
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Masahiko Hatatani, Tohru Moriya
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3434-3441
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Ferromagnetic spin fluctuations in two-dimensional itinerant electron systems are discussed by using the self-consistent renormalization (SCR) theory of spin fluctuations. There is no long range magnetic order at finite temperatures. The temperature dependences of the static and dynamical susceptibilities and the physical properties associated with the spin fluctuations such as specific heat, nuclear spin-lattice relaxation rate and electrical resistivity are treated with particular attention to the critical behaviors around the magnetic instability.
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Takuya Okabe
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3442-3448
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Based on the double exchange mechanism, a model for ferromagnet La
1-xM
xMnO
3 (M=Ca
2+, Sr
2+, Ba
2+, or Pb
2+) is developed. Our theory can well describe several features such as the crossing behaviour of the magnetization curve for different composition x and the steep increase of resistivity around T
c. We use only one free parameter, the e
g-derived band width W-- 0.5, eV. The Curie temperature T
c is shown as a function of x.
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Akimasa Sakuma
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3449-3458
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Ferromagnetism of the Kondo lattice model (KLM) in the classical spin limit has been studied by using the single site approximation in the functional integral method. The magnetic phase diagram of the ground state is qualitatively consistent with one predicted by Ueda et al., except for a small Hund coupling limit where we have found the ferromagnetic phase for a finite electron concentration range of 0
1/3J2. Further for small n, the localized spin system exhibits snake-type M-T curve which is often the case with one with the mean field approximation for the Heisenberg model under the external magnetic field. This reflects that the KLM is composed of two systems, localized spin and conduction electron systems, coupled each other.
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Hiroyuki Mitamura, Toshiro Sakakibara, Giyuu Kido, Tsuneaki Goto
Subject area: Magnetic properties and materials.
1995 Volume 64 Issue 9 Pages
3459-3470
Published: September 01, 1995
Released on J-STAGE: October 01, 1999
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Isothermal magnetizations of itinerant metamagnet Y(Co
1-xAl
x)
2, x=0.08-- 0.11, were measured in static fields up to 23, T at various temperatures 3.6-- 30, K. Temperature variation of the magnetization M is found to change dramatically around the metamagnetic field H
c, from ∂ M/∂ T>0 (H
c) to ∂ M/∂ T<0 (H≥ Hc). Using the thermodynamic relations, the field dependence of the electronic specific heat coefficient γ is estimated. The γ value is enhanced as H approaches Hc from lower field. However, the enhancement is weak and is not divergent, consistent with the first-order transition at Hc. There is a sudden decrease of γ at around Hc, indicating a significant reduction of the density of state or a suppression of the spin fluctuations. For H>Hc, gradual decrease of γ continues to higher fields. These results suggest that the spin fluctuation behavior of this system is strongly affected by the metamagnetic transition.
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