-
Masataka Mizushima
1993 Volume 62 Issue 12 Pages
4159-4162
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
A binary star system, which has a mutual orbiting rotational speed of ω
b, produces a time-dependent anisotropy of space at an observer. The equation of geodesic deviation shows that the resulting anisotropy of space gives rise to a gravitational force between two mirrors, which form an interferometer, and that force is proportional to ω
b2 times the anisotropy of space. Because 2π⁄ω
b is of the order of days or years, the rigidity
k⁄
mo of the interferometer, where
k is the force constant of a nongravitational force that supports the mirrors and
mo is the reduced mass of the mirrors, is much larger than ω
b2. The amplitude of the vibrational motion of the interferometer with frequency ω
b (in terms of its equilibrium length) is given by (ω
b2⁄(
k⁄
m0)) times the anisotropy of space. On the other hand, if we rotate the interferometer with an angular speed of ω of 1 radian/s or more, we can make
k⁄
mo<ω
2, in which case the factor (ω
b2⁄(
k⁄
mo)) disappears, and the rotating interferometer will be useful as a detector of the gravitational waves due to binary star systems.
View full abstract
-
Norio Kawakami
1993 Volume 62 Issue 12 Pages
4163-4166
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
An integrable model for SU(ν) electrons with inverse-square interaction is studied for the system with confining harmonic potential. We develop a new description of the spectrum based on the
renormalized harmonic oscillators which incorporate interaction effects via the repulsion of energy levels. This approach enables a systematic treatment of the excitation spectrum as well as the ground-state quantities.
View full abstract
-
Yoshihiro Ishibashi
1993 Volume 62 Issue 12 Pages
4167-4170
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The wave number (
k)-dependence of the average thermodynamic potential density
F(
k) in the incommensurate phase is discussed, especially in the vicinity of zero wave number. In the case of incommensurate phases such as in NaNO
2, (d
F⁄d
k)
k=0=0.
View full abstract
-
Lianjun Wu, Nobuyoshi Hosoito, Noriaki Nakayama, Teruya Shinjo
1993 Volume 62 Issue 12 Pages
4171-4173
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
A series of Co/Au(001) superlattices were prepared on GaAs(001) single-crystal substrates using an electron beam deposition method in an ultrahigh vacuum. X-ray diffraction spectra were measured with the scattering vector normal to the film surface, and diffraction peaks from the Co/Au(001) superlattices were observed throughout the entire measured range from low-angle to high-angle. For samples with noninteger numbers of atomic planes in one Co/Au bilayer unit, in the intermediate range (2θ: 20°∼31°) X-ray diffraction peaks indexed from the low angle side did not merge with those satellite peaks indexed from the Co/Au(002) fundamental peak in the high-angle range. This observation indicates a high crystalline quality for Co/Au(001) superlattices with a negligible fluctuation in layer thicknesses and a coherent interface structure.
View full abstract
-
Shin-ichi Kimura, Yasuhiko Sato, Fumitaka Arai, Kenichi Katoh, Mitsuo ...
1993 Volume 62 Issue 12 Pages
4174-4177
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Reflectivity spectra of R
3Au
3Sb
4 (R=La, Ce) polycrystals were measured in the photon energy range from 5 meV to 40 eV at 6, 78 and 297 K. A narrow energy gap was observed for both materials. In La
3Au
3Sb
4, it was seen that the energy gap of about 150 meV is an indirect one. The absorption due to the direct and allowed transition was observed around 0.7 eV. These results are consistent with the calculated band structure. In Ce
3Au
3Sb
4, it was seen that the energy gap of about 70 meV is a direct one. The gap is considered to consist of the occupied 4
f state and the unoccupied 5
d state.
View full abstract
-
Eiji Hashimoto, Yoshitake Ueda, Hirofumi Tamura, Takao Kino
1993 Volume 62 Issue 12 Pages
4178-4181
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Measurements have been made on the residual electrical resistivity in single crystals of high-purity aluminum (
RRR\simeq50000) at 4.2 K. The samples were cut from single-crystal plates with {110} surfaces. The axes of the samples were oriented parallel with the principal axes 〈100〉, 〈111〉 and 〈110〉. The results show strong anisotropy, previously not predicted for a normal metal with cubic symmetry. The resistivity increases in the order of the 〈110〉, 〈111〉 and 〈100〉 directions; the value along 〈100〉 is significantly larger than those of the other two directions.
View full abstract
-
Bunjyu Shinozaki, Takasi Kawaguti, Yasunobu Fujimori
1993 Volume 62 Issue 12 Pages
4182-4185
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The excess conductance σ′ and the magnetoconductance
Δσ due to superconducting fluctuations have been measured at temperatures near superconducting transition temperature
Tc of aluminum films. The data are analysed in terms of a current theory of the Maki-Thompson (MT) correction of which final expressions for σ
MT′ and
Δσ
MT depend on the electron mean free path
l but not on the electron phase-relaxation time. Experimental results agree well with the sum of the AL (Aslamazov-Larkin) term and the present MT term. The value of
l obtained by a best fit to the data on
Δσ is reasonable. However, it increases with increasing temperature.
View full abstract
-
Meiro Chiba, Kazuhiro Ohara, Yoshitami Ajiro, Takeshi Morimoto
1993 Volume 62 Issue 12 Pages
4186-4189
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
133Cs NMR experiment has been performed on CsCuCl
3 at 4.2 K under the applied magnetic field parallel to the crystal
c-axis. An anomalous spectrum has been observed at the critical field of 11.19 T, where the magnetization jump was detected previously. At the critical field, the spectrum is abruptly cut off with no hysteresis for the sweep direction of the magnetic field. The critical field is independent of the operating frequency of the NMR experiment. The result can be explained by the theoretical model of the field-induced transition due to the quantum spin fluctuation in the one-dimensional ferromagnet with
S=1⁄2.
View full abstract
-
Koichi Kindo, Tadashi Shibata, Tetsutaro Inoue, Yoshinori Haga, Takash ...
1993 Volume 62 Issue 12 Pages
4190-4193
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
A clear de Haas-van Alphen (dHvA) oscillation has been found in LaP doped with 2 atomic percent of Ce under a pulsed field up to 30 Tesla (T) at liquid helium temperature. The oscillation is superimposed on the paramagnetic saturation curve of Ce which does not show the Kondo effect. The Fourier spectrum of the magnetization curves gives an extremal cross-sectional area of the Fermi surface of 0.01 Å
−2, which is about a half-value of CeP. The ground state of the Ce atom is investigated by electron spin resonance (ESR) and a nearly isotropic
g-value of 1.37 is obtained, in agreement with the theoretical expectation for
Γ7, while the
g-value of field-cooled CeP is 2.93 which is close to that of
Γ8. The discrepancy is discussed using the neutron diffraction data.
View full abstract
-
Hiroyo Ono, Katsumi Irokawa, Akio Miyazaki, Masaru Komukae, Toshio Osa ...
1993 Volume 62 Issue 12 Pages
4194-4197
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Dielectric constants of a NaNH
4(SO
4)
1−x(SeO
4)
x·2H
2O system along the
c axis under stress-free and clamped conditions were measured in a temperature range from −210°C to 30°C. Examinations of the pyroelectric current were also carried out. The dielectric constants under stress-free and clamped conditions followed the Curie-Weiss law above the phase transition temperature. It was therefore suggested that the phase transition of the NaNH
4(SO
4)
1−x(SeO
4)
x·2H
2O system is caused predominantly by dielectric instability. A phase diagram of the NaNH
4(SO
4)
1−x(SeO
4)
x·2H
2O system was established from the results of dielectric measurements. It was found that the phase transition temperature of the NaNH
4(SO
4)
1−x(SeO
4)
x·2H
2O system exhibits a minimum value of −200°C at
x=0.3. The space group in the ferroelectric phase of NaNH
4SO
4·2H
2O was identified to be
P2
1 from the phase diagram.
View full abstract
-
Yan Wang, Yasunori Tominaga
1993 Volume 62 Issue 12 Pages
4198-4201
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Depolarized low-frequency Raman spectra of aqueous solutions of
L-ascorbic acid and its isomer
D-araboascorbic acid as a function of concentration have been investigated in the frequency region from −250 cm
−1 to 250 cm
−1 at 30°C. The reduced χ″(\barν) spectrum, which corresponds to the imaginary part of the dynamical susceptibility, due to the dynamical structure of water in aqueous solutions, was analyzed with the superposition of one Cole-Cole-type relaxation mode and two damped harmonic oscillator modes. The effect of
L-ascorbic acid on the dynamical structure of water is different from the effect of
D-araboascorbic acid.
View full abstract
-
Kazuhiro Hikami, Miki Wadati
1993 Volume 62 Issue 12 Pages
4203-4217
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
One-dimensional quantum particle system with
SU(ν) spins interacting through inverse square interactions is studied. We reveal algebraic structures of the system: hidden symmetry is the
U(ν)≅
SU(ν)⊗
U(1) current algebra. This is consistent with the fact that the ground state wave function is a solution of the Knizhnik-Zamolodchikov equation. Furthermore we show that the system has a higher symmetry, which is the
w1+∞ algebra. With this
W algebra we can clarify simultaneously the structures of the Calogero type (1⁄
x2-interactions) and Sutherland type (1⁄sin
2x-interactions). The Yangian symmetry is briefly discussed.
View full abstract
-
Tohru Morita
1993 Volume 62 Issue 12 Pages
4218-4223
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The diagrammatical approach to the exact solution of two-dimensional Ising model, developed for the system with spin 1/2 and 1, is extended to be applicable to the Ising model of spin
S greater than 1/2. The exact solution for the system on the square lattice and other lattices with non-crossing interactions is obtained only when the spin is half an odd integer, and the interaction between two spins
sj and
sk is expressed as −
Jjkφ
j(
sj)φ
k(
sk) in terms of one paramater
Jjk and odd functions φ
j(
s) and φ
k(
s) of
s satisfying |φ
j(
s)|=|φ
k(
s)|=1 for
s=−
S, −
S+1, …, and
S. The exact solution on the honeycomb lattice is obtained for all
S, for the cases when the interactions divided by the temperature are expressed in terms of
S+1⁄2 or
S parameters.
View full abstract
-
Hideo Shioda, Yohtaro Ueno
1993 Volume 62 Issue 12 Pages
4224-4232
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
By applying our Monte Carlo twist method we study the
Q=6 general clock model with next-nearest-neighbor interactions
Vnn in two dimensions (
d=2). By estmating the stiffness exponent ψ we find in some range of
Vnn an ordered phase of very soft rigidity with ψ close to 0.1 less than
d−1 (highest rigidity). This is a counterpart in
d=2 of the incompletely-ordered phases (IOPs) with ψ\simeq1.2 already found in the same model in
d=3 with
Vnn=0 which has two kinds of IOPs (IOP1 and IOP2). Further analyses including the profiles of twisted states indicate that this phase is the IOP2 where a set of three adjacent states are dominant and well mixed. The phase diagram obtained looks very similar to that of the
d=3 model except that the IOP1 cannot be found within the range of our study.
View full abstract
-
Masahiro Nakagawa
1993 Volume 62 Issue 12 Pages
4233-4239
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
A new method is proposed to evaluate the fractal dimensions of the self-affine data whose power spectra are in accord with a power law. It is on the ground of the logarithmic divergence of the moment of the power spectrum. From a crossover point of the logarithmic behaviour, a critical exponent of the moment can be obtained and related to the fractal dimension. A practical application involves an evaluation of the fractal dimensions of such self-affine data as vowels. As a result of the analyses of the critical behaviour of their moments, those dimensions are found to range over 1.60∼1.71.
View full abstract
-
Il-Tong Cheon
1993 Volume 62 Issue 12 Pages
4240-4242
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Effects of the opaqueness of metallic plates have been investigated on the energy shift of the γ-ray absorbed by the nucleus placed between two parallel plates.
View full abstract
-
Jae-Tack Jeong, Moon-Uhn Kim
1993 Volume 62 Issue 12 Pages
4243-4254
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Two-dimensional slow viscous flow around a finite vertical plate above a plane wall is investigated based on the Stokes approximation. The flow at infinity is a simple shear flow parallel to the plane wall and/or the plane wall translates parallel to itself. A formal expression for the flow is obtained by solving a three-part Wiener-Hopf equation. By evaluating the formal expression, streamline patterns for typical cases are presented and the flows near the edges of the plate are discussed. Force and moment exerted on the plate are also calculated.
View full abstract
-
Tawhida S. Basha, A. Abbas
1993 Volume 62 Issue 12 Pages
4255-4261
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
This paper presents results of cylindrical single Langmuir probe measurements of the electron and ion densities in argon and helium glow discharge plasmas. The gas pressure veries from 5 to 150 Pa. The electron density is determined from the electron probe current at the space potential. The positive ion density is determined from the probe ion saturated current according to Bohm pre-sheath model as well as according to collisional Zakrzewski and Kopiczynski model. At basic pressures of 80 Pa and higher, good agreement is obtained, for both gases, between the electron and ion densities with both models. For basic pressures less than 80 Pa down to 5 Pa, satisfactory agreement between the electron and ion densities is achieved with Zakrzewski and Kopiczynski model where the destruction of the orbital motion of ions in the sheath is still considered.
View full abstract
-
Gopalraja Praburam, Hiroshi Honda, Masao Sugawa
1993 Volume 62 Issue 12 Pages
4262-4268
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Suppression of drift waves by the application of externally launched lower hybrid waves has been observed experimentally in an ion-beam plasma system. Suppression is due to ponderomotive force which upshifts the frequency of the drift wave, thus enhancing the Landau damping of electrons. A nonlocal theory incorporating the effect of the finite mode structure is given to explain these experimental results.
View full abstract
-
Kimitaka Itoh, Sanae-I. Itoh, Atsushi Fukuyama, Masatoshi Yagi, Masafu ...
1993 Volume 62 Issue 12 Pages
4269-4276
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Theory of the
L-mode confinement in toroidal plasmas is developed. The Prandtl number, the ratio between the ion viscosity and the thermal conductivity is obtained for the anomalous transport process which is caused by the self-sustained turbulence in the toroidal plasma. It is found that the Prandtl number is of order unity both for the ballooning mode turbulence in tokamaks and for the interchange mode turbulence in helical system. The influence on the anomalous transport and fluctuation level is evaluated. Hartmann number and magnetic Prandtl number are also discussed.
View full abstract
-
Shin’ichi Takeda, Masanori Inui, Shigeru Tamaki, Kenji Maruyama, ...
1993 Volume 62 Issue 12 Pages
4277-4286
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The structure factors of liquid Te at 470°C and 570°C have been newly obtained by X-ray and neutron diffraction. A remarkable and clear difference has been found between X-ray and neutron diffraction results. The ion-electron correlation function and valence electron distribution were evaluated from this difference at two temperatures of 470°C and 570°C. The obtained electron charge distribution function shows two peaks at the distance around 0.80 Å and 1.70 Å just above the melting temperature of 470°C, which corresponds to the distribution of the lone pair electrons and the covalent bonded electrons around a central tellurium ion, respectively. At higher temperature of 570°C, a single peak is observed at the distance around 1.1 Å in the electron charge distribution function.
View full abstract
-
Kenji Maruyama, Shigeru Tamaki, Shin’ichi Takeda, Masanori Inui
1993 Volume 62 Issue 12 Pages
4287-4294
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Using neutron diffraction data for liquid Se and Te, the Reverse Monte Carlo simulations have been performed. For liquid Se at the temperatures of 250°C and 350°C, the obtained structure mainly consists of two-fold coordinated chains, but about 30% of Se atoms have three-fold coordination and many Se
3 triangles are observed. For liquid Te a large number of Te atoms have three-fold coordination and the structure of liquid is network-like, which is very different from that of liquid Se.
View full abstract
-
Masanori Aoki, Shozo Takeno, A. J. Sievers
1993 Volume 62 Issue 12 Pages
4295-4310
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Stationary anharmonic localized modes with eigenfrequencies appearing in the gap between the optic and acoustic frequency bands are studied for a one-dimensional diatomic lattice with hard or soft quartic anharmonicity. A systematic analytical scheme using the lattice Green’s function method combined with the rotating-wave approximation and its improved version is developed on the one hand, and extensive numerical experiments have been made on the other. The eigenfrequencies and profile functions of anharmonic gap modes are obtained both analytically and numerically. Good quantitative agreement between the theoretical result and the experimental ones is obtained for both of the gap modes due to the hard and soft quartic anharmonicity. It is shown that the spatial localization of the latter is much more pronounced than that of the former.
View full abstract
-
Akira Onodera, Boris A. Strukov, Alexander A. Belov, Sergei A. Taraski ...
1993 Volume 62 Issue 12 Pages
4311-4315
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Thermal and dielectric properties of LaBGeO
5, a new ferroelectric with a stillwellite-type structure are investigated. The specific heat,
Cp, shows one clear anomaly (
ΔS=0.114 R) at 802.5 K. The basic thermodynamic parameters are determined on the basis of the Landau theory. However, an additional hump in
Cp was found in a different sample just above
Tc. This dependence on samples is confirmed by the measurements of dielectric constants. The appearance of the new intermediate phase may be caused by some impurities or defects. The Rhodes-Wohlfarth plot suggests that the nature of the phase transitions is of the displacive-type.
View full abstract
-
Masayuki Hasegawa
1993 Volume 62 Issue 12 Pages
4316-4330
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
A self-consistent theory of freezing which is applicable to systems interacting through long-ranged potentials is presented. It consists of a new formulation of the modified weighted-density approximation (MWDA) based on the idea of the thermodynamic perturbation approach, in which the potential is split into a short-range (reference) part and a long-range part. The MWDA is used separately for the excess free energy of the reference system and the remaining contribution due to the long-range part of the potential. When applied to the one-component plasma, the theory yields results which are in reasonable agreement with the simulation data. It also provides a possible explanation for the reason why the usual approach, in which the solid is mapped onto a single effective liquid, fails for systems with long-ranged potentials.
View full abstract
-
Shin-ichi Kimura, Fumitaka Arai, Takashi Suzuki, Mikihiko Ikezawa
1993 Volume 62 Issue 12 Pages
4331-4337
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Reflectivity spectra of a magnetic semiconductor material Gd
2S
3 (=Gd
3−xV
xS
4, where V denotes vacancy and
x=1⁄3) have been measured in the energy range from 2 meV to 40 eV at 9, 20, 77 and 300 K. From the comparison between the optical conductivity and the photoelectron spectra, the energy position and the shape of the occupied and the unoccupied electronic states were obtained. Above 77 K, this material showed a metallic reflectivity spectrum, but an energy gap of about 7 meV opened on the Fermi level below 20 K. The origin of the nonmetal-metal transition was concluded to originate from the creation of a magnetic polaron state.
View full abstract
-
Norikazu Tomita, Atsushi Ikawa, Hideo Fukutome
1993 Volume 62 Issue 12 Pages
4338-4351
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Effects of the on-site electron-electron Coulomb interaction
U on bond alternation in the one dimensional half filled Hubbard model are studied by the resonating Hartree-Fock method. Two kinds of SDW neutral solitons
SA0 and
SB0 exist in a bond alternated lattice which are centered at a long bond and a short bond, respectively.
SA0 enhances but
SB0 suppresses the alternating bond order (ABO) due to bond alternation. Quantum fluctuations in the ground state involve more
SA0’s than
SB0’s because the former has lower energy than the latter with increasing bond alternation so that they enhance the ABO in the true ground state and consequently the bond alternation. The spin and singlet pair correlation functions show that electrons tend to make singlet pairs on nearest neighbor short bonds even from small
U’s and small bond alternations.
View full abstract
-
Mitsuo Kataoka, Terutaka Goto
1993 Volume 62 Issue 12 Pages
4352-4363
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The de Haas-van Alphen (dHvA) oscillations of the magnetostrictions and the elastic constants are investigated theoretically. The electron band with orthorhombic symmetry is treated in the effective mass approximation. For ω
sτ<<1 with the sound-wave angular frequency ω
s and the electron life time τ, Landau orbitals are formed in a deformed metal without affecting local ion motions. In this static approximation to the ion motion, the free energy of the electron-lattice system is calculated as a function of strains. This free energy reveals the acoustic dHvA oscillations and proves that their amplitudes strongly depend on both the direction of an applied magnetic field and the strain mode. It is emphasized that the present acoustic dHvA effect can be a good probe into the electronic properties of metals such as the Fermi surface and the electron-lattice coupling.
View full abstract
-
Jun Ogura, Tetsuro Saso
1993 Volume 62 Issue 12 Pages
4364-4372
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Static and dynamic properties of a magnetic impurity in insulators with a small energy gap are investigated by the poor man’s scaling, 1⁄
N expansion, the self-consistent perturbation method within the non-crossing approximation (NCA) and the quantum Monte Carlo (QMC) method. It is shown that the ground state of the magnetic impurity changes from the singlet to multiplet when the gap increases, as in the case of the magnetic impurity in a BCS superconductor, although there is a different feature compared to the latter. Critical value of the gap
Ec is found to be
Ec⁄
TK=2.0 by 1⁄
N expansion and NCA, while
Ec⁄
TK≈0.4∼0.9 by QMC, where
TK denotes the Kondo temperature. It is found by the poor man’s scaling that
Ec is enhanced (reduced) by the enhanced (rounded) gap-edge.
View full abstract
-
Toshikazu Nakamura, Tokutaro Komatsu, Gunzi Saito, Toshihito Osada, Se ...
1993 Volume 62 Issue 12 Pages
4373-4385
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The electrical resistivity measurements for the novel organic superconductor κ-(BEDT–TTF)
2Cu(CN)[N(CN)
2] (
Tc=11.2 K) [BEDT–TTF represents bis (ethylenedithiolo)tetrathiafulvalene] under pressure or in high magnetic field were studied. Several physical parameters, such as the superconducting transition temperature (
Tc), the depressibility of
Tc with pressure (−d
Tc⁄d
P), the residual resistance ratio (RRR), the upper critical field (
HC2), and the effective Ginzburg-Landau mass anisotropy between perpendicular and parallel to the conducting plane (
m⁄⁄⁄
m⊥), are determined. They are discussed in comparison with those of other κ-type organic superconductors with
Tc above 10 K; κ-(BEDT–TTF)
2Cu(NCS)
2 and κ-(BEDT–TTF)
2Cu[N(CN)
2]Br. A simple relation was observed between these parameters (
Tc, −d
Tc⁄d
P and
RRR) and the dimensionality of the electronic structures of these superconductors.
View full abstract
-
Keisuke Nakazawa, Kazuya Suzuki, Toshiaki Enoki, Ko Sugihara, Seiji Mi ...
1993 Volume 62 Issue 12 Pages
4386-4392
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The
c-axis resistivity ρ
c which indicates a metallic temperature dependence was measured in stage 1 and 2 potassium-hydrogen-graphite intercalation compounds (KH-GICs) in the temperature range of 1.5–300 K below 15 kbar. The pressure effect on ρ
c suggests a hopping conduction process for the
c-axis transport mechanism, which is governed by the number of conduction paths and the transfer integral across the intercalate layer. The magnitudes of ρ
c in stage 1 and stage 2 compounds are mainly dominated by the number of their impurity and defects concentrations in the conduction paths.
View full abstract
-
Koji Kobayashi, Ko Sugihara, Hisashi Oshima, Takuro Tsuzuku
1993 Volume 62 Issue 12 Pages
4393-4397
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
Thermoelectric power in
c-direction (
Sc) of highly oriented pyrolytic graphite (HOPG) exhibits a sharp negative dip around 20–30 K. This anomaly is ascribed to the phonon drag thermoelectric power (
Sp) related to the out-of-plane vibration and
Sp is calculated in close relation to the mechanism of
c-axis conduction. Major contribution to
Sc comes from
Sp which can provide a qualitative explanation of the observed results.
View full abstract
-
Makoto Matsui, Wataru Sasaki
1993 Volume 62 Issue 12 Pages
4398-4406
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Annealing processes have been studied in thermal-neutron irradiated, heavily arsenic-doped,
n-type germanium crystals with initial donor concentrations of 3.24×10
18, 3.32×10
18 and 5.20×10
18 cm
−3 by measuring the resistivity and the Hall effect after isochronal annealings. The concentration of conduction electrons, the resistivity and the Hall mobility recover stepwise at essentially the same annealing temperatures for the three quantities and different samples. In the Hall mobility recovery, “reverse” annealing is observed over an annealing-temperature range from 250 to 320°C for all samples, in contrast to monotonic recovery of the carrier concentration and the resistivity. The reverse annealing is interpreted as being due to dissociation of vacancy-arsenic complexes formed in the preceding annealing process.
View full abstract
-
Hideki Futagawa, Noboru Miura, Koji Yamada, Norihiko Kamata, Akira Kow ...
1993 Volume 62 Issue 12 Pages
4407-4413
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
We have observed a novel feature in the hot-electron magnetophonon resonance in
n-type germanium at pulsed high magnetic fields up to 40 T. In the longitudinal magnetophonon resonance, the resonance peaks appear as either maxima or minima depending on the difference in the effective mass between the initial and final states of the intervalley scattering by phonons. The results are interpreted in terms of the mobility change of conduction electrons at the resonance.
View full abstract
-
Takashi Hotta
1993 Volume 62 Issue 12 Pages
4414-4425
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The origin of superconductivity in cuprate oxide systems is studied from the first principle starting with the
d-
p model Hamiltonian. We derive the Dyson-Gor’kov equations which include the second order terms with respect to Coulomb repulsion
U between d-electrons both in normal and anomalous self-energy parts, and solve them completely in due consideration of full momentum and energy structures in the equations. We obtain the superconducting transition temperature
Tc by treating both the attractive interaction and the damping effect on an equal footing. As a result, it is shown that
d-wave superconductivity is possible under a suitable condition, though
Tc is suppressed by the damping effect. The possibility of obtaining high
Tc by including higher order terms in
U is discussed in connection with the experimental results on Tl-systems.
View full abstract
-
Hiroaki Kadowaki, Toshikazu Ekino, Hiroshi Iwasaki, Toshiro Takabatake ...
1993 Volume 62 Issue 12 Pages
4426-4437
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Successive phase transitions in the Kondo compound CePtSn are studied by neutron scattering experiments on a single-crystalline sample. Antiferromagnetic phase transitions are observed at
TN=6.2 K and
TM=3.8 K, which are second and first order transitions, respectively, in accord with the previous specific heat measurement. The magnetic structure is a single-
Q type
Snν=
aνe
ik·Rn+
aν*e
−ik·Rn with incommensurate modulation vectors
k=0.466
b* and 0.418
b* in the low (
T<
TM) and intermediate (
TN<
T<
TM) temperature phases, respectively. The polarization vectors
aν cannot uniquely be determined from scattering intensities, and thus those which reproduce the intensities are selected using a maximum entropy method. In the low-temperature phase, the polarization vectors have
a,
b and
c components, and the root mean square of the moment is
mrms=0.84±0.08 μ
B (
mrmsa=0.72,
mrmsb=0.31,
mrmsc=0.29 μ
B) at
T=2 K. In the intermediate-temperature phase, the polarization vectors have
a and
c components, and
mrms=0.60±0.06 μ
B (
mrmsa=0.56,
mrmsc=0.22 μ
B) at
T=4.8 K.
View full abstract
-
Kenji Nakajima, Kazuyoshi Yamada, Syoichi Hosoya, Tomoya Omata, Yasuo ...
1993 Volume 62 Issue 12 Pages
4438-4448
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Inelastic neutron magnetic scattering experiments were performed from the well characterized single crystal of La
2NiO
4.00 (
TN=328 K) to study the spin-wave excitations in this system. The large energy gaps are observed at the two dimensional zone center, namely 15.7 meV for the out-of-plane mode, and 4.1 meV or 7.9 meV below or above 70 K for the in-plane mode respectively. Combined with the higher energy scans carried out by the spallation neutron source, the whole dispersion relation was determined, which follows a linear spin-wave model. It provides the microscopic parameters of nearest neighbor exchange interactions in plane, two anisotropy energies corresponding to the out-of-plane and in-plane modes, respectively, 28.7±0.7 meV, 1.26±0.12 meV and 0.10±0.02 meV at 10 K. The scattering intensities also nicely follow the linear spin-wave model at the lowest temperature. The results are discussed with the previous experiments on the spin dynamics of La
2CuO
4.
View full abstract
-
Jun-ichi Igarashi
1993 Volume 62 Issue 12 Pages
4449-4457
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
We calculate the spin-wave dispersion and the sublattice magnetization up to second order in the 1⁄
S expansion for the antiferromagnetic Heisenberg model with nearest-neighbor (
J1) and second-neighbor (
J2) couplings on a square lattice. The corrections to the linear spin-wave theory for the spin-wave dispersion and the sublattice magnetization grow large when the frustration increases. The expansion seems to converge asymptotically well for
J2⁄
J1<0.35, leading to quantitative estimates for both quantities. The corrections are positive for
J2⁄
J1<0.4, making the Néel ordered state more stable than what the linear spin-wave theory predicts. When
J2⁄
J1 exceeds 0.4, the second-order corrections grow very large with negative sign.
View full abstract
-
Shingo Aoyama
1993 Volume 62 Issue 12 Pages
4458-4466
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Electrical resistivity is calculated on the basis of the effective nuclear Hamiltonian above and below the nuclear ordering temperature
Tc. The conduction electrons are scattered by the nuclear spins mediated by the f-electrons through the s-f exchange interaction and the hyperfine interaction. By the short range order, the resistivity increases or decreases from the value of the non-interacting nuclear spin system depending on the sign of the RKKY interaction and the size of
kF. In low temperatures the resistivity is calculated by the spin wave approximation. The
T-dependence reflects the crystal field anisotropy through the dispersion relation of the spin wave. It is shown also that the aspherical Coulomb interaction, which works sometimes to the resistivity at high temperatures, is not effective in this low temperature region.
View full abstract
-
Hitoshi Ohta, Seisaku Imagawa, Mitsuhiro Motokawa, Eiji Kita
1993 Volume 62 Issue 12 Pages
4467-4473
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
The dependences of the resonance fields and the FMR absorption intensities of Fe/MgO multilayered films on the thickness of the Fe layer have been obtained by the submillimeter wave FMR using the pulsed magnetic field up to 15 T at 4.2 K. The magnetic anisotropy of each film, which is determined by the frequency dependence of the FMR with the aid of the results of the magnetization measurements, can explain the angular dependence of the FMR completely. The dependence of FMR absorption intensity on the thickness of Fe layer, however, turned out to be rather different from the results of the magnetization measurements.
View full abstract
-
Mamoru Mekata, Nariyasu Yaguchi, Takeo Takagi, Tsukasa Sugino, Setsuo ...
1993 Volume 62 Issue 12 Pages
4474-4487
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Magnetic ordering in a rhombohedrally stacked triangular lattice antiferromagnet, CuFeO
2 was investigated on powder and single crystals by measurements of neutron diffraction, magnetic susceptibility, Mössbauer effect together with Monte Carlo simulations. CuFeO
2 was found to exhibit transitions at
TN1=16±0.5 K and
TN2=11±0.5 K. The low temperature phase has an orthorhombic magnetic unit cell with collinear moments along the
c-axis, whereas the intermediate temperature phase is a partially disordered phase with a monoclinic magnetic unit cell where 1/5 of moments remain paramagnetic. The Monte Carlo simulations for the Ising spin tiangular lattice antiferromagnet can reproduce the observed successive transition in the case of the exchange parameters 4
J3<2
J2∼
J1<0. This combination of exchange parameters gives an account for the stability of the collinear magnetic structure in CuFeO
2.
View full abstract
-
Hiroko Aruga Katori, Atsuko Ito
1993 Volume 62 Issue 12 Pages
4488-4502
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Systematic studies of a random mixture Fe
xMn
1−xTiO
3 with competing exchange interactions have been made by low-field dc-magnetization measurements. Typical behavior characterizing a spin-glass transition is observed in the samples with intermediate Fe concentrations. The samples with Fe- and Mn-rich concentrations undergo the transition to the antiferromagnetic phase, and the samples with certain concentrations reenter into the reentrant spin-glass phase at low temperatures. From these results, the concentration versus temperature phase diagram is determined. In Fe
xMn
1−xTiO
3 the characteristic properties of the spin-glass and reentrant spin-glass appear strongly, that is because Fe
xMn
1−xTiO
3 is a magnetically condensed system with strong frustration. The magnetic properties observed in the antiferromagnetic phase of this system have clarified that the spin configuration is quite different from those in ordinary antiferromagnets.
View full abstract
-
Mitsuo Wada, Yasuharu Yamashita, Akikatsu Sawada, Yoshihiro Ishibashi
1993 Volume 62 Issue 12 Pages
4503-4510
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The dielectric dispersion in the ferroelectric Li
2−xNa
xGe
4O
9 (
x≈1) single crystals has been measured in the frequency range from 120 Hz to 10 MHz around the transition temperature
TC=109 K. The Debye-type dispersion was observed in the MHz region. The relaxation time increases abruptly as
TC is approached from above, which shows the critical slowing-down of dielectric response. The relaxation time is 1.5×10
−8 sec at 0.5 K above
TC. The softening of the optical phonon has not been observed by Raman scattering measurement. The ferroelectric phase transition of Li
2−xNa
xGe
4O
9 (
x≈1) is the typical order-disorder one. The origin of the polydispersive nature and the sample dependence of the relaxation time are discussed.
View full abstract
-
Kazuo Gesi
1993 Volume 62 Issue 12 Pages
4511-4515
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The effect of hydrostatic pressure on the phase transitions in the deuterated crystal Ca
2Ba(C
2D
5COO)
6 (DDBP) has been studied by dielectric measurements in a temperature and pressure range of 170 K\lesssim
T\lesssim360 K and
p\lesssim650 MPa. The resultant
p-
T diagram is compared with that of the normal compound Ca
2Ba(C
2H
5COO)
6 (DBP). A marked deuteration effect is seen for the pressure-induced ferroelectric Curie temperature (the IV–V boundary); the deuteration causes almost parallel depress of the boundary by about 10 K. The deuteration effects are discussed in connection with those of Ca
2Sr(C
2H
5COO)
6 and Ca
2Pb(C
2H
5COO)
6.
View full abstract
-
Vadim. F. Aguekian, Yu A. Stepanov, Ichirou Akai, Tsutomu Karasawa, Te ...
1993 Volume 62 Issue 12 Pages
4516-4521
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
The exciton spectra of SnO
2 single crystals with the low and high concentrations of the oxygen vacancies (OV) are investigated. The series of luminescence lines adjacent to the lowest free exciton states (the excitons localized by the isolated OV and OV clusters) increases superlinearly with the optical excitation level. It is shown that the luminescence spectra of SnO
2 can be described as the zero-phonon and one LO-phonon assisted anihilation of the free and localized excitons. The shape of LO-phonon replicas of the free exciton luminescence corresponds to Maxwellian distribution of the excitons which have the effective temperature significantly higher than the lattice temperature in the case of pulse excitation level 10
6–10
7 W/cm
2.
View full abstract
-
Z. J. Li, K. L. Yao, Z. An, Z. G. Li
1993 Volume 62 Issue 12 Pages
4522-4526
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
Seven localized vibrational modes have been found for the soliton in
trans-(CH)
x for a two-dimensional extension of the SSH model that includes the bond-bending term, the Hubbard interaction and the electrostatic pinning. Three of them are infrared active, and they can be used to interpret the three observed infrared absorption lines at 500 cm
−1 (or 900 cm
−1), 1260 cm
−1 and 1370 cm
−1.
View full abstract
-
Biswanath Rath, K. Patnaik
1993 Volume 62 Issue 12 Pages
4527-4528
Published: December 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL
RESTRICTED ACCESS
-
Riki Kawashima, Takayoshi Saitoh, Hiroshi Isoda
1993 Volume 62 Issue 12 Pages
4529-4530
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
-
Yousuke Tanaka, Kazuyuki Watanabe
1993 Volume 62 Issue 12 Pages
4531-4532
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS
-
Mitsuru Sugisaki, Masaru Eguchi, Osamu Arimoto, Kaizo Nakamura, Makoto ...
1993 Volume 62 Issue 12 Pages
4533-4534
Published: December 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL
RESTRICTED ACCESS