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Kazuyoshi Takeda, Keita Miyake, Masako Hitaka, Tatsuya Kawae, Nariyasu ...
専門分野: Statistical physics and thermodynamics.
1994 年 63 巻 6 号 p.
2017-2020
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The partially disordered spins in the triangular antiferromagnetic lattice in CuFeO
2 have been studied by heat capacity measurements. A cusp and a sharp peak in the heat capacity curve were observed at T
N1=14.0± 0.5, K and T
N2=11.0± 0.5, K, respectively.The analysis of heat capacity revealed that the magnetic entropy associated with the anomaly in the heat capacity around T
N2 is attributable to the disordering of one-fifth of Fe
3+ spins. The present result is discussed in comparison with partially disordered states of CeSb and PrCo
2Si
2, anisotropic spin systems with frustration. The heat capacity cusp around T
N1 is compared with the characteristic thermal behavior for frustrated spin systems.
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Yoshimitsu Amagishi, Seiko Kitagawa
専門分野: The physics of plasmas and electric discharges.
1994 年 63 巻 6 号 p.
2021-2024
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Kinetic modes of the Alfvén wave in an inhomogeneous plasma are investigated by using a two-fluid theory including a finite pressure effect, the Hall effect, electron inertia and collisional effects. The dispersion relation involving the kinetic Alfvén wave, the surface electrostatic wave and the resistive wave is derived with the terms of ion-cyclotron frequency and electron-ion collisions, and it is also concluded that the observed waves in the experiment [Phys. Rev. Lett. 64 (1990) 1247;J. Phys. Soc. Jpn. 59 (1990) 2374] are kinetic Alfvén waves in a collisional plasma including ion-neutral collision effects.
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Naoki Toyoda, Kiyoshi Sakaue, Hikaru Terauchi, Takeshi Arai, Youichi M ...
専門分野: Structure of liquids and solids; crystallography.
1994 年 63 巻 6 号 p.
2025-2027
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
X-ray study of single-crystal C
60 was carried out at low temperatures to investigate the relaxational properties of the glassy phase. We observed the time-dependent X-ray integrated intensity of the reflection characteristic of the low-temperature stable phase. It is found that the relaxation times of molecular reorientation follow the Arrhenius law. The relaxation process is discussed in terms of a cluster model, in which the small crystal with the space group P2
13 is considered to appear in a matrix with the space group Pa3.
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Tsuyoshi Watanabe, Shozo Takeno
専門分野: Structure of liquids and solids; crystallography.
1994 年 63 巻 6 号 p.
2028-2031
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
A new kind of surface phonon mode is proposed to occur for a semi-infinite (SI) one-dimensional (1d) lattice with hard quartic anharmonicity. This is a nonlinear localized mode with p-like symmetry in the strong localization limit associated with the end of the SI 1d nonlinear lattice. The characteristic properties of these modes in contrast to conventional surface modes and bulk anharmonic localized modes are that its central position is located at a point 3/2-lattice-constant away from the end atom, and that only a few atoms undergo large excursion in comparison with the rest of the atoms.
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Yasuhiro Akutsu, Noriko Akutsu, Takao Yamamoto
専門分野: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1994 年 63 巻 6 号 p.
2032-2036
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Based on the terrace-step-kink (TSK) picture, the fluctuation property of a single step on the vicinal surface is studied by the Monte Carlo method. Logarithmic behavior of the squared step width W
2(y)-- A
Wln y (y: distance between two points on the same step) is confirmed for both the free-fermion TSK model and the non-free-fermion solid-on-solid (SOS) step model. The calculated amplitude A
W as a function of the step density ρ verifies the universal form A
W=1/(π
2ρ
2) for the free-fermion TSK model. For the SOS step model, A
W deviates from the universal form as ρ increases.
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Tadao Kasuya
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2037-2041
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Unexplained anomalous properties recently found in CeNiSn have been investigated based on the novel idea of a localized homogeneous mixed valence state developed recently to explain anomalies in SmB
6 and YbB
12. All the anomalies including most mysterious ones found in NMR and neutron scattering are explained consistently. It was shown that the simple Kondo model cannot explain the anomalies consistently. It is also important to differentiate impurity effects at low temperature.
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Kazumasa Miyake, Osamu Narikiyo
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1994 年 63 巻 6 号 p.
2042-2046
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
It is shown that the charge susceptibility in nearly half-filled two-dimensional (2D) metals, with technically nested Fermi surface, shows anomaly at the wave vector different from that for the spin susceptibility at low temperatures. Namely charge degrees of freedom behave there as if their “Fermi surface” corresponded to that of “holes” created in the Mott insulator. Such anomaly is caused by the Aslamazov-Larkin-type contribution of 2D antiferromagnetic spin fluctuations. This phenomenon gives a possible clue to resolve the paradox of normal state properties of high-T
c cuprates starting from the Fermi-liquid fixed point.
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Arisato Kawabata
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1994 年 63 巻 6 号 p.
2047-2051
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Electron transport of interacting electrons in a quantum wire is investigated. The resistance is calculated in the lowest order in the impurity potential taking account of the electron-electron interaction in the form of the vertex correction to the interaction with the impurities. To calculate the vertices we use the parquet diagram method, and the results by the renormalization group method on the transmission of single barrier are reproduced in the lowest order in the impurity potential. The case of coulomb interaction is investigated also and it is pointed out that the temperature dependence of the resistance is qualitatively equal to that for short-range interaction.
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Yoshio Kitaoka, Kenji Ishida, Kunisuke Asayama
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2052-2056
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The contrast between Zn- and Ni-impurity effects in YBa
2Cu
3O
7 and the imperfection-induced gapless superconductivity in Bi
2Sr
2CaCu
2O
8 reported previously are quantitatively analyzed based on the d-wave superconducting model. By taking account of the fact that the Zn impurity which caused the gapless superconductivity acts as a unitarity or strong scatterer, it is demonstrated that the Ni impurity does not give rise to the gapless superconductivity, although it is not so weak as to be treated in terms of Born scattering. The d-wave model can explain the characteristic feature such that even though T
c is moderately reduced by impurity scattering, the superconductivity changes into the gapless type with a finite density of states at the Fermi level.
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Shigeki Ohsugi, Yoshio Kitaoka, Hideaki Yamanaka, Kenji Ishida, Kunisu ...
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2057-2060
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The nuclear quadrupole resonance (NQR) study of
139La in La
2-xSr
xCuO
4 was systematically carried out in the Sr-content range from 0.085 to 0.15 at 1.4 and 4.2, K in zero field. The linewidth of the
139La NQR spectrum for the (± 1/2→ ± 3/2) transition was found to increase especially at x=0.115, associated with the occurrence of magnetic ordering. This is hence considered to be responsible for the decrease of the superconducting transition temperature around x=0.115. Since the spectrum does not broaden with for the (± 5/2→ ± 7/2) transition down to 1.4, K, the ordered Cu-moments are considered to exist in the Cu-O
2 sheets.
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Noriaki Sato, Kimihiro Imamura, Takuo Sakon, Takemi Komatsubara, Izuru ...
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2061-2065
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
We find that La
3Ni is a type-II superconductor with a Ginzburg-Landau parameter, κ=49. The temperature dependence of the specific heat reveals two peaks, one of which appears in the superconducting phase and is ascribed to the symmetry change of the superconducting order parameter. We observe nearly T
3 power law dependence of the specific heat, implying that the superconducting energy gap function has nodes on points. The lower critical magnetic field H
c1 in the lower temperature phase is larger than that in the higher temperature phase.
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Takuhiro Ogawa, Yoshikazu Suzumura
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2066-2069
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The strongly correlated electronic states of the periodic Anderson model in the presence of the electron-phonon (e-p) interaction have been examined to understand the properties of the metal-insulator transition for DCNQI-Cu salts. By making use of the slave-boson mean-field theory based on the previous work [J. Phys. Soc. Jpn. 62 (1993) 3244], it is shown that the first-order Peierls transition from the metallic state with the heavy electron mass into the insulating state with the local spin takes place by varying the temperature and/or the e-p coupling constant.
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Hidetsugu Kitatani
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2070-2073
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
For the ± J Ising models, it is proved that p
c (the concentration of +J bonds) of the multicritical point in the model A does not exceed that in the model B (p
c, A≤ p
c, B) when the model A is obtained from the model B by adding bonds, each of which takes +J or -J with the same probability weight as in the model B. The proof holds for any lattice structure, dimension of the lattice and range of the interactions.
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Hiroaki Kadowaki, Taku Sato, Hideki Yoshizawa, Toshikazu Ekino, Toshir ...
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2074-2077
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Spin excitation of the Kondo semiconductor CeNiSn has been studied by neutron scattering in a wide Q space. Below the coherence temperature of 20, K, the excitation spectra show pronounced peaks at (h/2π)ω = 4 and 2, meV, at Q=(Q
a, ½, Q
c) and (0 0 1), respectively. The observed Q dependence of the 4, meV excitation implies that the corresponding dynamical antiferromagnetic-correlation is quasi-one-dimensional along the b-axis, and is polarized mainly along the a-axis.
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Eduardo Di Mauro, Walter Sano
専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1994 年 63 巻 6 号 p.
2078-2081
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The study of the perpendicular part of the Electron Paramagnetic Resonance spectra of Cu
2+, characterized by a variable number of lines when doped in Ammonium Bromide, has been extended examining crystals grown in acidic solution (pH≈1.6). The 19 lines of the spectra that have been observed at 300, K are interpreted like in our quite recent study of Cu
2+:NH
4Br (basic). The new hf / parameter is A
⊥=66± 2 (the values of A are given in units of 10
-4, cm
-1) and the shf / parameter is A
′⊥=47± 3. At 77, K the spectra have ten lines and are interpreted combining seven shf / lines and four hf / lines. The parameters determined are: g
z=2.048± 0.005, g
x=2.284± 0.005, g
y=2.189± 0.005, A
z=108± 3, A
x=78± 3, A
y=0± 3, A
x′=0± 3 and A
y′=76± 3. The hf / and shf / interactions are in the same order and are responsible for the characteristic spectra.
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Yoshihiro Ishibashi
専門分野: Dielectric properties and materials.
1994 年 63 巻 6 号 p.
2082-2084
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The structural phase transition induced by biquadratic coupling of two different modes is discussed utilizing the Landau-type free energy. The phase diagrams are presented, in which the first-order transition lines associated with simultaneous destabilization of two modes appear.
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Tomozo Tomoyose
専門分野: Dielectric properties and materials.
1994 年 63 巻 6 号 p.
2085-2088
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
By using the pseudopotential method, the transverse effective charges Z
TZB and Z
TRS of zincblende and rock-salt structures, respectively, are presented as a function of the Phillips ionicity f
i. The critical ionicity F
c is analytically determined from the critical point where Z
TZB is equal to Z
TRS. Its average value for various tetrahedral compounds F
c is estimated to be F
c=0.78, which is very close to the Phillips critical ionicity F
i=0.785. The relationship between F
c and F
i is discussed with respect to the structural instability caused by the large effective charge Z
T.
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Tetsusuke Hayashi, Ping Gu, Masayuki Watanabe
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 年 63 巻 6 号 p.
2089-2092
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Emission and excitation spectra of the luminescence in Pb
1-xCd
xI
2 solid solutions have been investigated in the range of x between 0.5 and 0.8. Emission band observed near the absorption edge is attributed to the luminescence associated with Pb ion clusters dispersed in CdI
2 matrix. Time-resolved measurements of the emission spectra reveal that the emission band consists of singlet and triplet components. The energy split between the singlet and triplet states is found to increase with decrease in the cluster size. The result is discussed in relation to an exciton Bohr radius.
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Tsutomu Tomari, Masao Doi
専門分野: Mechanics, elasticity, and rheology.
1994 年 63 巻 6 号 p.
2093-2101
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The swelling dynamics of a gel undergoing the volume transitionis studied theoretically for one dimensional case. It is assumed thatthere is a sharp interface between the swollen region andthe unswollen region. The position of the interface and the volumechange of the gel is calculated as a function of time by numericalsimulation and analytical calculation. It is shown that(i) the characteristic time of the swelling is proportional toL
20ζ / |σ
c|(L
0, ζ and σ
c being the gel size, the friction constant and the transition stress respectively), which diverges at the equilibrium transition temperature and that(ii) the volume of the gel increases in proportion to√t until it reaches the final volume.
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Masayoshi Okamoto
専門分野: Fluid dynamics.
1994 年 63 巻 6 号 p.
2102-2122
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
An eddy-viscosity-type representation of the Reynolds stressis investigated with the aid of a two-scale direct-interactionapproximation (TSDIA). The second- and third-order analyses ofthe TSDIA are applied to the Reynolds stress. Using these results, the nonlinear part of the Reynolds stress andthe turbulent-energy dissipation rate equation are discussed in detail.Non-equilibrium effects of turbulence are also incorporated intothe nonlinear part in addition to the simple eddy-viscosity one.Further, using the experimental data, we confirm that the K-ε model is improved bythe non-equilibrium property.
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Keisuke Araki, Jiro Mizushima, Sinichiro Yanase
専門分野: Fluid dynamics.
1994 年 63 巻 6 号 p.
2123-2132
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The thermal instability of a fluid layer confined in a spherical shellis investigated on a linear theory basis.The dependence of the critical Rayleigh numberon the functional form of the gravity distribution is investigated.An asymptotic analysis is also made for very thin layer caseby an expansion with R
-1, where R is the radiusof the inner sphere normalized by the thickness of the fluid layer.The critical Rayleigh number is obtained asRa
c=Ra
c(0)[1+(1-(3/2)λ
G)R
-1]+O(R
-2), where λ
G is the density ratio of the fluidto the matter inside the inner sphere.The asymptotic expression of the Rayleigh numberis shown to be a good approximation even for R of order one.
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Seigo Kishiba, Koji Ohkitani, Shigeo Kida
専門分野: Fluid dynamics.
1994 年 63 巻 6 号 p.
2133-2148
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
A transition process from vortex layers into vortex tubesthrough the Kelvin-Helmholtz instability in decaying homogeneous turbulenceis studied numerically in terms of the helical decomposition.For smooth initial conditions high-vorticity regionswith positive and negative helicity generally take the form of blobs.In the early stage with almost inviscid dynamicsthese blobs become flatter and layer-like, approaching simultaneously each other.In the next stage a pair of high-vorticitystrips with opposite-signed helicity attach each other.It forms a precursor of a vortex tubewith an internal dipole / structure, which corresponds to the surrounding dipoles of high energy-dissipation.At later times two high-vorticity tubes with opposite-signed helicityjoin in series into a single vortex tube.They are separated again by the viscous diffusion.The recovery to a reflectional symmetry state is also studiedusing a strongly helical initial condition.
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K. N. Mehta, K. Narasimha Rao
専門分野: Kinetic and transport theory of fluids; physical properties of gases.
1994 年 63 巻 6 号 p.
2149-2156
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
This paper examines the effect of permeability on boundary layerflow over an infinite permeable bed rotatingin a mass of still fluid occupying the upper half space.The slip boundar condition proposed by Beavers and Joseph
1) isemployed to analyse the dynamic coupling of boundary layer flowwith the Darcy flow induced in the bed due to transfer of momentumby seepage into the porous medium, occupying the lower half space below the fluid.The effect of permeability and rotation on the componentsof slip velocity and shear stress in the radialand transverse directions is examined.Rotation and tangential slip are found to cause axial flow reversalin the boundary layer.Dependence of the location of point of flow reversalon rotation and permeability has been also studied.
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Kohji Yamamoto, Nobuaki Ikuta
専門分野: Kinetic and transport theory of fluids; physical properties of gases.
1994 年 63 巻 6 号 p.
2157-2167
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The electron collision cross sections of CF
4 havevery singuler forms with very high values of vibrational excitationcross sections in the region of Ramsauer minimum of momentumtransfer cross section, and the electron transport propertiesshow peculiar variations with E/N. There have been several reports onthe electron swarm data in CF
4 and on the cross section dataderived from the swarm data and of beam experiments.In our laboratory, some efforts have also been made usingthe FFT Monte-Carlo simulation accuratelly to calculatethe electron transport properties in CF
4 andto obtain the collision cross sections well fitwith the experimental swarm data. However, it has been recognizedto be very difficult strictly to reproduce the peculiar transportproperties. In this paper, the backgrounds of disagreementsbetween the experimental and the calculated datawith various cross section sets are discussed.
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Jiro Todoroki
専門分野: The physics of plasmas and electric discharges.
1994 年 63 巻 6 号 p.
2168-2176
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Averaged resistive MHD equations are derived by using the Lagrangianformalism. The assumption is that the perturbation is of singletoroidal harmonics on the special magnetic coordinates Jacobianof which is independent of the toroidal angle. The metrics containedin the obtained resistive equations are those appearing in the averagedequilibrium equations. The local stability conditions are also derived.
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Ken–ichi Hattori, Kiyoshi Hayase, Yasuyuki Sato
専門分野: The physics of plasmas and electric discharges.
1994 年 63 巻 6 号 p.
2177-2184
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Reversed field pinch configuration with a poloidal-open divertorhas been realized quasi-continuously on TPE-2M device with close-fittingshell. Significant increase of liner temperature near the separatrix hasbeen observed, indicating strong heat transport through the separatrix, consistent with calculated last closed flux surface from measured magneticfields. Spectroscopic measurement has shown that impurities from thelimiters and the first wall rapidly increase right after divertorconfiguration is realized, which are supposed to be due to a shortconnection length between the separatrix and the wall. Characteristicsof resistive kink modes have been found to be similar to those withoutdivertor. Apppearance of local magnetic fluctuations near separatrix, however, have been observed by the onset of divertor fields, but notto grow to the disruption.
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Kozo Hoshino, Fuyuki Shimojo, Mitsuo Watabe
専門分野: Structure of liquids and solids; crystallography.
1994 年 63 巻 6 号 p.
2185-2193
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
We have investigated theoretically the temperature dependence ofthe dispersion relation, derived from the dynamical structure factor, of expanded liquid alkali metals on the basis of the effective pairpotential obtained by the pseudopotential theory, the static structure factor calculated with the modified hypernetted-chain (MHNC) approximation and the dynamical structure factor calculated with the viscoelastic approximation. It is shown that the characteristic features of the observed temperature dependence of the dispersion relation of expanded liquid rubidium are well reproduced theoretically and that those features are common to all expanded liquid alkali metals. The quality of the viscoelastic approximation is assessed by comparing the theoretical results with those of the molecular dynamics simulation. The universal feature of the liquid alkali metals near the triple point is discussed by scaling the pair potential and the dispersion curve.
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Han–Min Kim, Tadashi Fukumoto, Shinji Hayashi, Keiichi Yamamoto
専門分野: Structure of liquids and solids; crystallography.
1994 年 63 巻 6 号 p.
2194-2201
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
MoO
3 microcrystals were produced by heating a Mo wire in mixture gas of Ar and O
2, and their Raman spectra were measured. Although previous electron microscopic studies revealed only an orthorhombic structure of the microcrystals, the present spectra show additional Raman peaks not attributable to the orthorhombic structure. The intensities of the additional peaks depend strongly on the zone of particle collection, total gas pressure and partial O
2 pressure. From a comparison between the present Raman data and previous reports on various types of MoO
3 crystals (metastable forms), we find that the additional peaks are due to metastable forms of MoO
3 crystals.
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Yoshihiro Ishibashi, Vladimir Dvorak
専門分野: Equations of state, phase equilibria, and phase transitions.
1994 年 63 巻 6 号 p.
2202-2205
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
A Landau-type free energy function is proposed to reproduce the phase sequences, which are given rise to by the instability of the modes at the X-point of the I4/mmm phase as seen in La
2MO
4 (M=Cu, Ni etc.) compounds. Emphasis is placed on the appearance of the Pccn phase. Typical phase diagrams obtained by varying the coefficient values appearing in the free energy function are presented.
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Takeji Hashimoto, Toshihiro Ogawa, Chang Dae Han
専門分野: Equations of state, phase equilibria, and phase transitions.
1994 年 63 巻 6 号 p.
2206-2214
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
It has been considered that elastic scattering profiles gradually change with temperature across the order-disorder transition (ODT) of block copolymers and hence a unique determination of the ODT temperature (T
ODT) is difficult by scattering methods alone. We report here our finding that the scattering experiments with a high temperature-resolution, involving a temperature increment of smaller than or equal to 1°C, enables a straightforward, unequivocal determination of T
ODT even for a low molecular weight polystyrene-block /-polyisoprene copolymer. Moreover we found that the high temperature-resolution scattering experiment can reveal the very sharp ODT of the copolymer occurring in a very narrow temperature range of less than 1°C; the experimental results with a low temperature-resolution can easily lead us to overlook the sharpness of the ODT and to misunderstand the nature of the transition.
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Masayuki Hasegawa
専門分野: Equations of state, phase equilibria, and phase transitions.
1994 年 63 巻 6 号 p.
2215-2224
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
A self-consistent theory of freezing developed by the author (J. Phys. Soc. Jpn. 62 (1993) 4316) is applied to systems interacting through inverse-power potentials. The theory is based on the idea of the thermodynamic perturbation approach and consists in a generalization of the modified weighted-density approximation of Denton and Ashcroft (Phys. Rev. A 39 (1989) 4701). The results of applications are in good agreement with the simulation data and usefulness of the theory is confirmed for systems interacting through soft-core or long-ranged potentials. Both theoretical and numerical comparisons between the present and other similar approaches are also made.
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Satoru Ohta, Yoshiya Adachi, Takejiro Kaneko, Motoyoshi Yuzuri, Hajime ...
専門分野: Thermal properties of condensed matter.
1994 年 63 巻 6 号 p.
2225-2230
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The lattice parameters a(T) and c(T) as a function of temperature(T) for rhombohedral-Cr
2Se
3 and trigonal-Cr
2Te
3 have been measured in the temperature range between 15, K and 300, K.As T increases, a(T) for Cr
2Se
3 increases up to a magnetic order-order transition temperature T
t above which it suddenly shrinks with the change Δ a/a=-1.1× 10
-3, while c(T) smoothly increases through T
t. In Cr
2Te
3, a(T) decreases up to about 250, K and then increases while c(T) increases in the temperature range measured. The obtained results are qualitatively discussed on the relation beteen the moment stability and volumetric expansion.
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Toshihiko Tsuneto
専門分野: Transport properties of condensed matter (nonelectronic).
1994 年 63 巻 6 号 p.
2231-2234
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Treating ideal frost heave on the phenomenological level, we introduce the transport coefficient associated with the boundary between solid and porous material filled with liquid. We regard this coefficient central for basic understanding of the kinetics of frost heave.
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Akira Sugiyama
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2235-2251
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Asymptotic expression for Fourier transform of a regular functionf(x) is estimated by transforming f(x) into ∫ F(x-z)g(z)dz, where F(x) has a singularity at x=0 and the asymptotic expression for Fourier transform of F(x) is estimated by the usual Lighthill's method. As in I, the transforms are applied to derive the interaction potentials in metals at non-zero temperatures. Now F(x)=xlog|x|, x
2log|x|, and x
2[log|x|]
2 are discussed, since they play important roles in deriving asymptotic expressions of interaction potentials V
3[cos(2k
Fr)/(2k
Fr)
3]+V
4[sin(2k
Fr)/(2k
Fr)
4at zero temperature. In a previous paper, by using F(x)=1/x, the temperature dependence of the first term was considered, but now that of both terms also are done. Fourier transforms of generalized function (1/x)log|x+a| and some of related functions, for example (x+a)(x-a)log|x+a|log|x-a|, are given.
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R. A. Jishi, Daisuke Inomata, Kenji Nakao, M. S. Dresselhaus, G. Dress ...
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2252-2260
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The symmetry properties of chiral monolayered carbon nanotubes, along with the method of zone-folding, are used to study their electronic and lattice properties. The energy bands and phonon modes are classified according to the irreducible representations of the 1D periodicity of the chiral nanotubes.
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Kazuhiro Ikezawa, Mahito Kohmoto
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2261-2268
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The one-dimentional quasiperiodic tight-binding model is-ψ
n+1-ψ
n-1+λ V(nω)ψ
n=Eψ
n, where ω is an irrational number and V is a periodic function, i.e., V(x+1)=V(x). In the Harper model V(nω)=cos(2π nω), all the states are critical at the critical coupling λ
c=2. The critical properties of the spectrum and the wavefunctions for ω=√{2}-1 (the inverse of the silver mean) are numerically studied by the scaling and multifractal methods.The results are compared with the golden mean case ω=(√{5}-1)/2. Some universal properties are proposed.
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Tetsuhiko Tomiki, Yoshiiku Ganaha, Tomoyoshi Futemma, Tohru Shikenbaru ...
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2269-2289
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The Kramers-Kronig derived complex dielectric constant, energy loss functions and effective number of electrons of YAP are presented in the region of 6, eV--120, eV for the light polarized parallel to each of the three crystallographic axes. The peak value of ε
2 spectrum at 33.34, eV, the highest-energy component of the bands associated with five resonance transitions from the Y
3+, 4p
6 level, is found to be proportional to the site number of Y
3+/cm
3 in the lattices of YAG, YAP and Y
2O
3. The maxima due to plasma oscillations are derived at --23, eV and --36, eV in each volume loss function. The energy dependence of the dielectric constant is found to be in substantial agreement in the region of 50, eV--120, eV with that calculated by the Drude formula with the use of the peak energy and half value width of the loss maximum at --36, eV. The above continuum is superposed on the features led by doublet lines at 78.4, eV and 78.8, eV which originate from the transitions from the Al
3+L
2, 3 levels.
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Hiroshi Yamagami, Akira Hasegawa
専門分野: Electron states in condensed matter.
1994 年 63 巻 6 号 p.
2290-2302
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
We derive the Fermi surface for LaRu
2Ge
2 by a self-consistent relativistic APW method within the framework of a local-density approximation.The Fermi surfaces thus obtained are composed of four hole sheets and an electron sheet, all of which have no open orbits. The Fermi surface topology is consistent with the experimental results for the high-field transverse magnetoresistance. These Fermi surfaces explain reasonably well the absolute magnitude and the angular dependence of the de Haas-van Alphen (dHvA) frequency-branches. Moreover, we use the theoretical Fermi surface of LaRu
2Ge
2 to re-examine an origin of the dHvA frequency-branches for a ferromagnetic CeRu
2Ge
2 regarded as non-Kondo-lattice system.
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Shinji Kawaji, Katsunobu Hirakawa, Makoto Nagata, Tohru Okamoto, Tetsu ...
専門分野: Electronic transport in condensed matter.
1994 年 63 巻 6 号 p.
2303-2313
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Properties of the breakdown of the quantum Hall effect due to current have been measured in specially designed samples with the width ranging from 10 to 120, μm made from a GaAs/AlGaAs heterostructure wafer at temperatures between 0.5 and 1.2, K in magnetic fields up to 23, T. Critical current in the onset of the breakdown is proportional to the sample width. The critical current density does not depend on temperature but depends on the Hall-plateau quantum number i for i=1, 2 and 4 where R
H(i)=h/ie
2. Experimental results can be explained by production of dissipative carriers by inter-Landau-level transitions from the filled Landau level to the empty Landau level cuased by strong local electric fields in the extended states enhanced due to the localization.
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Jun–ichi Yamada, Masafumi Sera, Masatoshi Sato, Takashi Takayama ...
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2314-2323
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Relationship between successive structural transitions and transport anomalies of La
2-x-yNd
yBa
xCuO
4 has been studied, where electrical resistivities ρ, Hall coefficients R
H, thermoelectric powers S and ultrasonic sound velocities V
s were measured. The transport properties exhibit no anomalous behavior at T
d2, the critical temperature of the transition from the low temperature orthorhombic (LTO1) to the low temperature tetragonal (LTT(Ba)) phase, indicating that the conduction electrons are not affected by this transition. Instead, a sudden decrease in S is observed with decreasing temperature for samples with x -- 0.125 at T
′d3 --70, K. Although T
′d3 seemed to coincide with the temperature T
d3 of the tetragonal → orthorhombic transition reported by Hara et al., results of the present X-ray diffraction study do not indicate any evidence for the existence of such a transition.
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Shin–ichi Shamoto, Takanori Kiyokura, Hiroshi Harashina, Masatos ...
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2324-2330
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Specific heat jumps ΔC at the superconducting transition temperature T
c have been estimated from reversible magnetizations of YBa
2(Cu
1-xM
x)
3O
6+y (M=Zn and Ni). The y-dependence of ΔC/T
c(≡ γ
M) is in good agreement with that of Loram et al. [Phys. Rev. Lett. 71 1740 (1993)] taken by direct specific heat measurements. The significant y-dependence of γ
M(x)/γ
M(0)-T
c(x)/T
c(0) curves cannot be explained by conventional theories of pair breaking due to magnetic or nonmagnetic scatterings for d-wave order parameters. The present results and other experimental results reported previously indicate that electron localization effects play an important role in determining the behaviors of impurity-doped high-T
c oxides.
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Jun"ichiro Hara, Katsuhiko Nagai
専門分野: Superconductivity.
1994 年 63 巻 6 号 p.
2331-2336
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Superconducting transition temperature of thin films in magnetic field is investigated. The linearized gap equation is derived by a quasiclassical Green's function method, which correctly includes the boundary effects and the impurity scattering effects. From the properties of the gap equation, it can be rigorously shown that the transition temperature is not enhanced by magnetic field. The temperature dependence of the critical field is numerically calculated in the clean limit.
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Hiroaki Kadowaki, Masahumi Kohgi, Kenji Ohoyama, Mitsuo Kasaya
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2337-2342
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Magnetic structure of the Kondo compound CePdSn is studied by neutron diffraction experiments on a single-crystalline sample. Below T
N=7, K, Ce moments establish a single-Q type ordering S
nν=a
ν e
ik· Rn+a
ν*e
-ik· Rn with incommensurate modulation vector k=0.473b
*. The polarization vectors a
ν cannot uniquely be determined from scattering intensities, and thus those which reproduce the intensities are selected using a maximum entropy method. The polarization vectors have a, b and c components with root mean square of the moment m
rms=0.82± 0.08, μ
B (m
arms=0.59, m
brms=0.48, m
crms=0.30, μ
B) at T=1.5, K.
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Tadashi Fukuhara, Hideyuki Sato, Yoshichika Onuki
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2343-2348
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Electrical resistivity, thermoelectric power, Hall coefficient, magnetic susceptibility and magnetization of binary uranium-tin compounds U
3Sn
2 and U
3Sn
5 have been measured in the temperature range of 1.3, K to room temperature. The experimental results indicate that both U
3Sn
2 andU
3Sn
5 are ferromagnetic below about 60, K and 45, K, respectively, although for U
3Sn
5 a some kind of magnetic order starts below about 75, K.
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Yosikazu Isikawa, Toshio Mizushima, Junji Sakurai, Katsunori Mori, Ang ...
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2349-2358
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The intermetallic compound CeNi
2Al
5 is an orthorhombic dense-Kondo compound with a magnetic transition temperature at 2.6, K.We have carried out magnetization and neutron diffraction measurements to study the magnetic structure of CeNi
2Al
5 using a powder sample and a single crystalline sample. It is found that the magnetic structure is sine-wave modulated with a propagation vector k=(1/2, 2/5, 1/12). The maximum amplitude of magnetic moment is equal to 1.54, μ
B and its direction is tilted 8 degrees from the b-axis toward the a-axis.
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Kazuo Hida
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2359-2364
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The magnetic properties of the ferromagnetic-ferromagnetic-antiferromagnetic trimerized spin-1/2 Heisenberg chain are studied theoretically. The high temperature susceptibilty and the ground state saturation magnetic field are calculated and the exchange energies of the trimer compound 3CuCl
2·2dx are determined. The magnetization curve is obtained by numerical diagonalization of finite size systems. The result explains the low temperature magnetization data for 3CuCl
2·2dx with the exchange energies obtained as above. It is predicted that the magnetization curve has a plateau at 1/3 of the saturation magnetization if the ferromagnetic exchange energy is comparable to or smaller than the antiferromagnetic exchange energy.
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Tosizumi Aoki
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2365-2373
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The spin-1/2 Heisenberg antiferromagnet with the nearest neighbor interaction J
1 and the next nearest neighbor one J
2 is studied on the square lattice by use of the self-consistent spin-wave approach, in which an on-site exclusion principle, i.e., (S
jy)
2+(S
jz)
2=1/2 with the x-axis taken as a quantized one is satisfied at any lattice point j on the average. From this constraint, the zero-temperature long-range order σ
0 and ground-state energy E
0 are determined as a function of α=J
2/J
1. The behaviors of σ
0 and E
0 near α=0.5 are very different from the ones of the ordinary spin-wave theory based on the Holstein-Primakoff transformation. For example, our calculation predicts the vanishing long-range order at α=0.5. It is emphasized that the on-site exclusion principle fairly well suppresses the quantum spin fluctuations highly enhanced by the frustration.
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Kunihiko Maezawa, Tadasi Fukuhara, Katsuhiko Nishimura, Yosikazu Isika ...
専門分野: Magnetic properties and materials.
1994 年 63 巻 6 号 p.
2374-2381
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The transverse magnetoresistance and de Haas-van Alphen (dHvA) effect in ferromagnetic RENi (RE: Pr, Nd and Sm) have been studied in fields up to 120, kOe and at temperatures down to 1.3, K. It was found that the Fermi surfaces of the three compounds contain an open surface along the b axis as in a non magnetic LaNi. On the other hand, the c-directional open surface was not found in PrNi and NdNi, being different from LaNi. Many dHvA frequency branches with the frequencies range of 2MG to 50MG were found. These branches show that the Fermi surfaces of these compounds are altered from that of LaNi by a relatively large spin splitting of the conduction band.
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Masahiro Matsumura, Yusaku Takayanagi, Hideki Yamagata, Yasukage Oda
専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1994 年 63 巻 6 号 p.
2382-2392
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
Cu-NQR spectra in YBa
2(Cu
1-xCo
x)
3O
7+ywere investigated systematically from x=0 to 0.18. In the normal state, T=100, K, the integrated intensities of the spectra for both Cu(1) and Cu(2) sites decrease rapidly with increasing x, which indicates that the large region around Co atom extending to 4--5th n.n. in Cu(1)-chain plane and 3rd--4th n.n. in Cu(2)O
2 plane are wiped out from observation. From temperature dependence of the spectra, the magnetic ordered state associated with Co moments is confirmed to coexist with the superconducting state. The magnetic transition temperature, T
M, is estimated from temperature dependence of the resonance intensities. At 1.5, K, the abnormally broad spectra ranging from 6 to 130, MHz appear, indicating the local moment formation at Cu(2) sites in the region wiped out at 100, K. Some discussions are made on the origins of the destruction of the superconductivity from the experimental results.
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G. van der Laan
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1994 年 63 巻 6 号 p.
2393-2400
発行日: 1994/06/01
公開日: 1999/10/01
ジャーナル
認証あり
The sumrules for X-ray absorption and photoemission [Thole et al., Phys. Rev. Lett. 68 (1992) 1943; 70 (1993) 2499] which relate the integrated signals of the magnetic circular and linear dichroism to the orbital magnetic moment and quadrupole moment are generalized to point group symmetry. The polarization dependence of the spectra is obtained by separating the geometry from the physical properties. The number of fundamental spectra is equal to the number of total symmetric representations of the recoupled moment in the point group. Cylindrical symmetry is particularly simple because it has the natural basis lm. The presented results can be useful for measurementsof magnetic materials that contain transition metal, rare earth or actinide ions using linearly and circularly polarized X-rays.
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