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Fumiaki Shibata, Chikako Uchiyama
1993 Volume 62 Issue 2 Pages
381-384
Published: February 15, 1993
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A rigorous solution is found for a basic equation which determines the time evolution of the nonlinear spin relaxation process. Spin coherent representation is used to transform an original operator equation into a Fokker-Planck-type
c-number equation for the probability density which is expanded in terms of spherical harmonics. Then the expansion coefficients are completely determined in the form of a continued fraction. Relevant averages such as moments and cumulants are calculated.
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Akira Onuki
1993 Volume 62 Issue 2 Pages
385-389
Published: February 15, 1993
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We present a general theory of dynamics of two-component surfactants on surfaces separating two fluids. The surface free energy consists of two contributions: one is determined by the surface curvature and the surfactant densities and the other is the gradient part arising from areal inhomogeneities of the surfactant densities. Our dynamic equations together with generalized boundary conditions at the surface can be used to describe highly nonlinear phenomena in which phase separation and surface deformations are coupled. Our theory can also be reformulated for cases with a nonconserved order parameter.
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Koji Ohkitani
1993 Volume 62 Issue 2 Pages
390-394
Published: February 15, 1993
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A nonlinear ordinary differential equation for peak vorticity is proposed phenomenologically for 3D inviscid flows. This typically predicts that the peak vorticity behaves approximately as \sqrt
A[sin {
r\sqrt
A(
t*−
t)}]
−1 and the peak strain as \sqrt
A[tan {
r\sqrt
A(
t*−
t)}]
−1, where
r,
A and
t* are constants. Numerical study of 3D Euler equations performed both in physical and Langrangian marker spaces is, at early stages consistent with assumptions underlying the above predictions, giving an alternative interpretation of apparently exponential growth of vorticity. It is not known if this evolution persists, leading to a finite-time singularity.
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Eiji Nishi, Nobuaki Ikuta
1993 Volume 62 Issue 2 Pages
395-398
Published: February 15, 1993
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Curves of reduced mobility versus reduced electric field of gaseous ions in gases of different species, for example alkali ions in rare gases, usually have a hump on the right-hand side of the flat part in the low reduced field (
E⁄
N) region. Such curves have been explained to be caused by the potential well formed by an induced dipole attraction potential and a steep repulsion potential. On the other hand, mobility curves with humps have been obtained with a model cross section which rapidly increase with the decrease in relative velocity through analysis utilizing the flight time integral (FTI) method. This model can also explain the temperature dependence of mobility curves.
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Kimitaka Itoh, Sanae-I. Itoh, Atsushi Fukuyama
1993 Volume 62 Issue 2 Pages
399-402
Published: February 15, 1993
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Turbulent ion motion caused by sawtooth crash is analyzed in the framework of the magnetic stochasticity model of the sawtooth crash. The average current profile changes much more slowly than the pressure profile after the onset of the crash, so that inhomogeneity of the parallel current along the field line is generated. This causes a perpendicular current with a short scale length, leading to the ion cross field motion.
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A. V. Belushkin, J. Tomkinson, L. A. Shuvalov, R. M. Fedosyuk
1993 Volume 62 Issue 2 Pages
403-406
Published: February 15, 1993
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The low-temperature lattice dynamics of K
1−x(NH
4)
xH
2PO
4 mixed crystals have been studied using high-resolution inelastic-neutron-scattering on powders for
x=0.0; 0.06; 0.1; 0.18; 0.3; 0.6 and 0.9. The influence of ammonium ion concentration on the hydrogen dynamics has been analysed. The mean square displacements of hydrogen bonded acid protons are found to be larger in the glass phase than in the ordered ferroelectric or antiferroelectric phases. It was found that a vibrational mode at 16.8 meV is strongly coupled with the ferroelectric modes.
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Takashi Itoh, Takashi Konishi
1993 Volume 62 Issue 2 Pages
407-410
Published: February 15, 1993
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Electron diffraction patterns and specific heat at constant pressure (
Cp) are recorded in a temperature range between approximately 300 K and 500 K for a nylon 66 crystal precipitated at 418 K from 0.05-wt% 1,4-butanediol solution. The
Cp is found to take a maximum value at 468 K (
Tt) under 0.1 MPa (atmospheric pressure). Three reflections of 100, 010 and 110 can be observed independently in an electron diffraction pattern, all of which show symmetrical single-peak profiles at temperatures lower than
Tt, while 010 and 110 profiles are found to be asymmetric or to have shoulders in the smaller-diffraction-angle region at
Tt. These results give the first evidence that two crystalline phases coexist or that first-order phase transition occurs at
Tt in the nylon 66 crystal.
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Tadao Kasuya, Yasunori Kaneta, Osamu Sakai
1993 Volume 62 Issue 2 Pages
411-415
Published: February 15, 1993
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Pressure effects on the electronic states in LaSb and CeAs are studied in detail based on high-pressure dHvA measurement. In LaSb, it was shown that even for small carriers, the Fermi surfaces do not change uniformly because of a strong
k-dependent
p-
d mixing effect on the conduction band and strong deviation from
k2-dispersion of the hole band. Strong anisotropy found in
c11 acoustic dHvA was attributed to the above mechanism. A magnetic polaron lattice, inserted in the 4
fΓ7 ground state, is able to explain unusual properties in CeAs, as well as in CeP.
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Hideyuki Sato, Tadashi Kumano, Yuji Aoki, Takeo Kaneko, Ryôichi ...
1993 Volume 62 Issue 2 Pages
416-419
Published: February 15, 1993
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We observed anomalous field dependence of Hall resistivity on Fe/Cr samples exhibiting large magnetoresistance. Hall resistivity of Fe(12.5)/Cr(12.5) shows a maximum near 2.3 T, above which it decreases 25%. The result was explained by the field-dependent decrease of the side-jump and skew scatterings in these samples. We also observed a clear correlation between the layer periodicity dependence of negative magnetoresistance and anomalous Hall resistivity in lower fields.
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Kazuhiro Kuboki
1993 Volume 62 Issue 2 Pages
420-423
Published: February 15, 1993
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The effect of gauge fields representing the fluctuations of the local constraint and those of the phases of the bond order parameters is examined for the uniform RVB state, which is a mean-field (MF) solution of the
t-
J model within the slave-boson formalism. It is found that the crossover temperature for the Bose condensation of holons,
TBE, below which the system may be essentially considered to be a Fermi liquid, is considerably reduced as compared with that in the MF approximation. The temperature dependences of the transport relaxation rate and the electrical resistivity are also examined.
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Shingo Katsumoto, Kousei Kamigaki, Masaya Ishida, Naokatsu Sano, Shun- ...
1993 Volume 62 Issue 2 Pages
424-426
Published: February 15, 1993
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We measured low-temperature conductance of epitaxially grown NiAl crystalline wires. In highly conductive samples, we observed time dependent conductance fluctuation, which was attributed to the motion of scattering centers. In low-conductance samples, the temperature dependence of the conductance was well described by the 1⁄\sqrt
T relationship predicted by the theory of weak localization.
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Gendo Oomi, Yoshiya Uwatoko, Kunihide Okada, Yoshihisa Obi, K\={o}ki T ...
1993 Volume 62 Issue 2 Pages
427-430
Published: February 15, 1993
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The effect of pressure on the electrical resistance and the magnetoresistance of (Fe 30 Å/Cr 11 Å)
22 superlattices has been investigated at high pressures up to 16 kbar and high magnetic fields up to 50 kOe. It is found that the electrical resistivity ρ decreases with increasing pressure, having a rate of (1⁄ρ)(∂ρ⁄∂
P)=−8.7×10
−3 kbar
−1 at room temperature, and that the magnetoresistance (MR) ratio
Δρ⁄ρ
s at 4.2 K is approximately constant below 8 kbar but decreases rapidly with increasing pressure above 8 kbar. The saturation field
Hs increases with pressure.
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Hideyuki Sato, Yuji Aoki, Yoshihiko Kobayashi, Hidefumi Yamamoto, Teru ...
1993 Volume 62 Issue 2 Pages
431-434
Published: February 15, 1993
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We present the first measurement of the field dependence of thermal conductivity in Cu/Co/Cu/Ni(Fe) multilayer film which shows large magnetoresistance of 50% at low temperatures. We found a large field dependence of similar magnitude in thermal conductivity with hysteresis, which suggests that the conduction electron scattering responsible for the giant magnetoresistance is mostly large angle and elastic in nature, at least at low temperatures.
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Naoki Kawashima, Nobuyasu Ito
1993 Volume 62 Issue 2 Pages
435-438
Published: February 15, 1993
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The three-dimensional ±
J Ising spin glass model is investigated by means of Monte Carlo simulation. In uniform fields of various strength, the Edwards-Anderson susceptibility χ
EAQ is calculated at
T=0.9
J which is lower than the transition temperature in the zero-field case. It is found that χ
EA decreases monotonically when the field strength is increased and that the data do not suggest a phase transition in a finite field. The best parameters for the scaling function of the form χ
EA(
H)\simeq
lψ\ ildeχ
EA((
H−
Hc)
l−φ) are estimated to be
Hc=0.00(10)
J, ψ=2.16(22) and φ=−1.13(6). These results support the hypothesis that the phase transition does not exist in a finite magnetic field.
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Kazuo Hida
1993 Volume 62 Issue 2 Pages
439-442
Published: February 15, 1993
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The phase-dependent generalized string order introduced by Oshikawa in the VBS (valence bond solid)-type states of the integer spin chain is extended to the spin-1/2
J−
J′ alternating Heisenberg chain with antiferromagnetic
J. The numerical diagonalization and the bosonization analysis show that the generalized string order remains finite in the ground state of the present model for −∞<
J′<
J, taking the maximum at
J′=0. The characteristic feature of the phase dependence of the generalized string order also coincides with that of the spin-1 VBS state. This reconfirms the notion that the Haldane state of the spin-1 chain and the dimerized state of the alternating chain belong to a single phase characterized by the local singlet-type correlation.
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Masaaki Matsuda, R. J. Birgeneau, H. Chou, Yasuo Endoh, M. A. Kastner, ...
1993 Volume 62 Issue 2 Pages
443-446
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Neutron scattering experiments have been performed to study the dynamic spin properties of single-crystal La
1.86Sr
0.14Cu
0.988Zn
0.012O
4 (
TC=16 K). The width of
S(
Q, ω) in momentum space decreases at low ω and at low temperatures. The intensity at low energies at the incommensurate peak position (π(1−δ), π) shows a broad maximum as a function of temperature around the superconducting transition temperature
TC. This behavior is qualitatively similar to that observed by Thurston
et al. in La
1.85Sr
0.15CuO
4 (
TC=33 K).
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Yoh Kohori, Yukihiro Noguchi, Takao Kohara
1993 Volume 62 Issue 2 Pages
447-450
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NMR and NQR signals of
55Mn in site II were observed. The electric quadrupole coupling constant and the asymmetry parameter were estimated to be
e2qQ⁄
h=30 MHz and η∼0, respectively. The nuclear spin lattice relaxation rate, 1⁄
T1, is proportional to \sqrt
T, which indicates βMn to be an itinerant antiferromagnetic system with
TN∼0 K. The value of 1⁄
T1 at site II is about 20 times larger than the value at site I. The electronic state of Mn at site II is more magnetic than that at site I.
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Kohji Mizoguchi, Yusuke Nakai, Susumu Ikeda, Akane Agui, Yasunori Tomi ...
1993 Volume 62 Issue 2 Pages
451-454
Published: February 15, 1993
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In order to study the deuteration effect in hydrogen-bonded compounds such as KH
2PO
4, hydrogen and deuterium modes in KH
2PO
4 and K(D
xH
1−x)
2PO
4 (
x=95%) were investigated by means of inelastic neutron-scattering measurements over a wide energy range. By comparing Raman spectra of KH
2PO
4 and KD
2PO
4 with neutron-scattering spectra, the vibrational modes of deuterium and those of PO
4 tetrahedrons in the energy range of 30<ε<150 meV have been investigated. At least two deuterium modes have been found at 87 meV and 106 meV.
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Katsuhiro Kaneko, Yasuji Kashiwase, Motokazu Kogiso, Masahiro Mori, Ma ...
1993 Volume 62 Issue 2 Pages
455-458
Published: February 15, 1993
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Intensity increase and decrease of fluorescent X-rays from the exit and entrance surfaces for the incident X-ray, respectively, are observed, when the 220 Bragg reflection of the incident radiation of wavelength 0.7093 Å is excited in perfect germanium crystals with μD=9.57 and 16.0. The experiment is performed using a triple-crystal spectrometer and the radiation from a Mo target in a conventional X-ray tube monochromatized by the silicon symmetric 111 reflection and collimated by the triple 220 reflections in a channel-cut silicon crystal. The experimental intensity profiles agree well with those calculated using the intensity formulae given by Annaka (J. Phys. Soc. Jpn. Vol.
23 (1967) 372).
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Hiroshi Sakurai, Fumitake Itoh, Hiroshi Maruyama, Akihisa Koizumi, Ken ...
1993 Volume 62 Issue 2 Pages
459-463
Published: February 15, 1993
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The first systematic measurements of circular magnetic X-ray dichroism (CMXD) effects at the
K-edge in 3
d-transition metal alloys have been made in Fe–Ni alloy over a wide composition range. It has been found that the CMXD spectrum at the Fe
K-edge is similar to that at the Ni
K-edge in each alloy, indicating that the CMXD spectra at the
K-edge mainly reflect an itinerant character of 4
p-states. The features of the CMXD spectra correspond to those of X-ray absorption near-edge structure (XANES) spectra, reflecting the change of crystal structure. The signal intensities around the absorption edge energy,
E0, have strong Ni concentration dependence, suggesting a close relationship between the CMXD effects around
E0 and the spin polarization of 3
d-states.
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Satoshi Tanaka, Akio Kotani
1993 Volume 62 Issue 2 Pages
464-467
Published: February 15, 1993
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Resonant X-ray emission spectra (RXES) due to the Cu 3
d→2
p electronic transition under the Cu 2
p→3
d resonant excitation in La
2CuO
4 and CuO are theoretically investigated. It is predicted that, with this spectroscopy, one can obtain direct information on the difference of the
a1g states between La
2CuO
4 and CuO, which is a characteristic difference in the electronic states between the so-called
p-
type high-
Tc superconductors and CuO, as has been shown in our theoretical analysis of the Cu 2
p-XES under the excitation of a Cu 2
p electron to a high energy continuum. Strong polarization dependence of the Cu 2
p-RXES enables us to determine the electronic structure. It is pointed out that the 2
p-RXES is a powerful probe in the study of the 3
d electronic states in transition metal compounds subjected to the crystal field, anisotropic hybridization and 3
d multiplet couplings.
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Kazuhiro Hikami, Miki Wadati
1993 Volume 62 Issue 2 Pages
469-472
Published: February 15, 1993
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One-dimensional quantum particle system with spins is considered. The Hamiltonian of the system (Calogero-Moser spin system) is
(
Remark: Graphics omitted.)
where
pj=−
i∂⁄∂
xj and σ
j is the Pauli spin operator associated with
j-th particle. We prove the integrability of the model through the quantum inverse scattering method. By introducing the annihilation and creation-like operators from the Lax operator, we construct the ground state. The wave function is of Jastrow-type. Further, we discuss a generalization of the model to SU(
M) spin case.
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Kazuaki Nakayama, Miki Wadati
1993 Volume 62 Issue 2 Pages
473-479
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Kinematics of moving curves in two dimensions is formulated in terms of intrinsic geometries. The velocity is assumed to be local in the sense that it is a functional of the curvature and its derivatives. The modified Korteweg-de Vries (mKdV) equation and its hierarchy are included in the theory when the normal velocity obeys a recursion relation. Curves corresponding to solutions of the mKdV equation are explicitly constructed.
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Taro Nagao, Miki Wadati
1993 Volume 62 Issue 2 Pages
480-488
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Correlation functions are evaluated for the Jastrow-product variational wave functions in one dimension. Discrete version of the integration method for random matrices is introduced for the evaluation. The results are expressed in terms of orthogonal polynomials on a discrete measure.
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Hiroshi Orihara, Yoshihiro Ishibashi
1993 Volume 62 Issue 2 Pages
489-496
Published: February 15, 1993
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We have derived expressions for the nonlinear dielectric susceptibility of a ferroelectric liquid crystal and a uniaxial ferroelectric crystal on the basis of equations of motion. Our results are different from a formula proposed by Nakada [O. Nakada: J. Phys. Soc. Jpn.
15 (1960) 2280], which was obtained from a tentative assumption. The temperature and frequency dependences of the third-order dielectric constant of a ferroelectric liquid crystal will be presented.
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Takeshi Kawabe, Yoshiro Kondo
1993 Volume 62 Issue 2 Pages
497-505
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Mandelbrot sets of the complex logarithmic map (
Remark: Graphics omitted.) have complicated and miscellaneous structures with various periods for 0≤arg(
Zn)<2π, and they are displayed by computer graphics. Period-adding sequence can be clearly found near the boundary with fixed points region. The Hopf bifurcation occurs at the points on the boundary, and quasi-periodic chaos appears Cantor-like on a line segment of the complex
C-plane where |
Zn|=1 is satisfied. Lyapunov exponent is also shown by contour maps in the complex
C-plane.
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Takashi Ishihara, Yukio Kaneda
1993 Volume 62 Issue 2 Pages
506-513
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Estimations of the time micro scales of Lagrangian strain tensors are obtained by dynamical analysis based on the Navier-Stokes equation for three dimensional turbulence at very high Reynolds number.
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Hideo Sugama, Masao Okamoto, Masahiro Wakatani
1993 Volume 62 Issue 2 Pages
514-523
Published: February 15, 1993
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We investigate the Vlasov equation in the stochastic magnetic field as a stochastic Liouville equation and derive the equation for the ensemble-averaged distribution function. The term resulting from the stochastic magnetic field has the derivatives with respect to both the velocity and the real space coordinates, which is a contrast to both the real space diffusion as seen in the guiding center picture and the velocity space diffusion as in the quasi-linear theory of the Vlasov equation including the electric field fluctuaions. We find that this term retains the mass and energy conservation properties of the original Lorentz force due to the stochastic magnetic field and yields the additional force in the momentum equation. This additional force produced by the stochastic field gives the drift velocity which corresponds to the familiar real space diffusion of the guiding center in the stochastic field. The finite Larmor radius effect on the diffusion is also estimated.
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Gen-ichi Kurita, Masafumi Azumi, Takashi Tuda
1993 Volume 62 Issue 2 Pages
524-535
Published: February 15, 1993
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The effect of anomalous electron and ion viscosity induced by the stochastization of magnetic field line on sawtooth crash in a tokamak is investigated by using the reduced set of resistive MHD equations. As the perturbation grows beyond some amplitude, the most unstable mode is turned from the pure resistive mode into the one induced by the anomalous electron viscosity, and the growth rate suddenly increases, as observed in some experiments. After that, the growth of perturbation is decreased due to the anomalous ion viscosity. The sawtooth crash time is prolonged in spite of the explosive growth due to the electron viscosity. However, it is not completely suppressed by the effect of anomalous ion viscosity.
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S. Patnaik, M. Seshasayee, Toshio Yamaguchi, Masaharu Nomura, Hitoshi ...
1993 Volume 62 Issue 2 Pages
536-543
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A structural investigation for a 50AgI–20Ag
2O–30CrO
3 (in mole %) glass has been carried out by using X-ray diffraction (XRD) and the extended X-ray absorption fine structure (EXAFS) techniques. The analysis of the EXAFS spectrum of the glass at the Ag K-edge reveals that the distance between a silver (I) and an iodide ions,
rAg–I, and the average number of iodide ions around an Ag
+,
nAg–I, are 2.874(4) Å and 1.6(1), respectively. Two Ag–O distances separated by only 0.38 Å (
ΔrAg–I) are deconvoluted from the total Ag–O peak in the spectrum. The results by the X-ray diffraction measurement coincide with those by the EXAFS study within experimental uncertainties:
rAg–I=2.860(1) Å,
nAg–I=1.34(1), and
ΔrAg–I=0.35 Å. The intramolecular structural parameters of CrO
3 are determined to be
rCr–O=1.718 Å, and
nCr–O=5.58. Short range ordering of atoms is discussed on the basis of the radial distribution function (RDF).
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Yoshiyuki Shirakawa, Sigeru Tamaki, Hideo Okazaki, Masayoshi Azuma
1993 Volume 62 Issue 2 Pages
544-551
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The magnetic susceptibilities of molten cuprous halides and their mixtures have been measured as a function of temperature.
The temperature dependence of susceptibilities in molten CuBr and CuI show small paramagnetic deviations compared to those in molten potassium halides. The composition dependence of CuCl–CuI and CuBr–CuI melts obey the Wiedemann rule, while the molten CuCl–CuBr system exhibits a large deviation from this rule.
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Eiji Hashimoto
1993 Volume 62 Issue 2 Pages
552-555
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Doppler-broadened lineshapes of positron annihilation in zinc have been measured as a function of temperature between 4.2 and 270 K after deformation and annealing up to various temperatures. The experimental results are well described in terms of a generalized trapping model where positrons become trapped in deep traps (
e.g., jogs) via shallow traps (dislocation lines). It has been found that the positron trapping rate to the dislocation line decreases rapidly with increasing temperature up to about 80 K, whereas above 80 K the trapping rate is basically constant. The binding energy between a positron and a dislocation line has been shown to be about 50 meV.
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Sumiyoshi Fujiki
1993 Volume 62 Issue 2 Pages
556-562
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The cluster variation method is applied to the ferromagnetic six-state clock model on the triangular lattice up to the hexagonal cluster approximation. The Kosterlitz-Thouless type phase transition of the model is studied by using the coherent anomaly method (CAM).
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Yoshifumi Sakamoto, Junjiro Kanamori
1993 Volume 62 Issue 2 Pages
563-572
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A lattice gas model which incorporates the Takayanagi mechanism stabilizing the (7×7) structure of the Si(111) surface is proposed. Monte Carlo calculations are carried out on the model to show that it is applicable to the surface both below and above the transition. The phase diagram and diffuse scatterings of electron in the (1×1) phase within the kinematical approximation are presented. The phase transition from the (7×7) state to the (1×1) is shown to be of the first kind, and it is shown that the model can reproduce diffuse spots around the (\sqrt3×\sqrt3) Bragg points just above the transition. The underlying mechanism is also discussed in detail. Moreover, the disappearance of stacking faults in the (1×1) phase is concluded from the calculation. The interrelation between the reconstructions of Si(111) and Ge(111) is discussed in a unified way on the basis of the calculations. The recent real-time STM observation of the surface at the transition performed by Miki
et al. is also discussed.
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Tetsuhiko Tomiki, Yoshiiku Ganaha, Tohru Shikenbaru, Tomoyoshi Futemma ...
1993 Volume 62 Issue 2 Pages
573-584
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The spectra of absorption constant in the intrinsic absorption tail region of α-Al
2O
3 single crystals at 297 K, 78 K and 10 K are presented for the electric fields of incident light parallel to the optic axis 〈c〉 of α-Al
2O
3 and normal to it. The absorption tail spectra obey the Urbach rule for each polarization, indicating that absorptions in the tail region result from the direct interband transitions. The optical anisotropy characterized by the Urbach rule is interpreted in terms of the bond length O
2−–Al
3+ participating in the absorption processes. The spectra of reflectivity are presented in the range of photon energies from 4.6 eV to 120 eV for electric fields parallel to 〈c〉 and normal to it. Spectral positions of main maxima in the reflectivity spectra for each polarization are determined at 297 K and 10 K; the spin-orbit doublet of the Al
3+ L
2,3 is revealed at 78.67 eV and 79.12 eV for the first time in the case of α-Al
2O
3.
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Chikara Sugiura
1993 Volume 62 Issue 2 Pages
585-591
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With a two-crystal vacuum spectrometer, the Cl
− Kα emission spectra in fluorescence are measured for a series of alkali chlorides MCl (M=Li, Na, K, Rb and Cs). By using the measured
Kα emission spectra, the previously reported Cl
− Kβ emission spectra, ultraviolet photoelectron spectra, and optical-gap data, the energy position of the bottom of the conduction band is shown in the high-resolution Cl
− L2,3 absorption spectra of alkali chlorides obtained by Iguchi
et al. The first sharp peak of the Cl
− L2,3 absorption is identified as being due to a core exciton, the energy level of which is formed below the bottom. The binding energies of the excitons are estimated to be 0.9 (±0.1), 1.2 (±0.1), 1.3 (±0.1), 1.1 (±0.1) and 0.7 (±0.1) eV for LiCl, NaCl, KCl, RbCl and CsCl, respectively.
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Hiroshi Yamagami, Akira Hasegawa
1993 Volume 62 Issue 2 Pages
592-603
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On the basis of the itinerant-electron model for the 4f electrons, the energy band structure and the Fermi surface are calculated for the metamagnetic heavy-electron compound CeRu
2Si
2 having the low-temperature electronic specific heat coefficient γ of 350 mJ/K
2 mol. by a self-consistent symmetrized relativistic APW method with the exchange and correlation potential in a local-density approximation. The main Fermi surface consists of a large closed hole sheet and a complicated electron sheet like a jungle gym. The Fermi surface topology is consistent with the experimental result for the high-field magneto-resistance. By comparison with the electronic structure of LaRu
2Si
2, effects of the 4f bands on the Bloch states on the Fermi surface in CeRu
2Si
2 are investigated in detail. Strong evidences for existence of the electron sheet are found in available experimental de Haas-van Alphen frequencies. The enhancement factor for γ is estimated as 38.
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Kaichi Saito, Susumu Matsuo, Tsutomu Ishimasa
1993 Volume 62 Issue 2 Pages
604-611
Published: February 15, 1993
Released on J-STAGE: May 29, 2007
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Magnetic properties of two kinds of Ga–Mg–Zn alloy samples were studied. One is Ga
20Mg
40Zn
40 icosahedral phase which was thermally stable below about 615 K, the other is Ga
18.5Mg
41.5Zn
40 alloy which exhibited amorphous-like X-ray diffraction pattern with no sharp peaks. The icosahedral phase showed a linear relationship between the magnetic susceptibility and the square of temperature. The improvement of the specimen quality resulting from heat treatment made the temperature dependence enhanced and the paramagnetism reduced. The amorphous-like sample did not show the temperature dependence of the magnetic susceptibility. These facts afford the experimental evidence that, in terms of Pauli paramagnetism, the electronic density of states at Fermi level of the icosahedral phase is strongly affected by the band-structure originating from the quasiperiodicity.
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Hideo Yoshioka, Hidetoshi Fukuyama
1993 Volume 62 Issue 2 Pages
612-623
Published: February 15, 1993
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Effects of correlation of the spin scattering between different measurements in the presence of the spin glass ordering have been investigated for mesoscopic fluctuations of Josephson currents in SNS junctions and those of persistent currents in isolated Aharonov-Bohm (AB) rings. It is found that, because of the absence of the time reversal symmetry, fluctuations of Josephson currents do not vanish even if the phase difference of two superconductors is zero and those of persistent currents in the absence of AB flux is also not zero. Moreover the characteristic length of exponential decay of the fluctuation of Josephson currents can be much longer than that of the average.
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Ko Sugihara
1993 Volume 62 Issue 2 Pages
624-633
Published: February 15, 1993
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Theory of the
c-axis conduction in graphite intercalation compounds was proposed by Sugihara and by Shimamura. Though two theories apparently seem to be different, the underlying physics is the same. In this article the previous treatments are largely revised and extended. To account for a maximum of ρ
c vs
T curve observed in some low stage compounds, a new mechanism is introduced and a comment on the semiconductor-like
T-dependence of ρ
c in high stage GICs, is presented. An expression of the
c-axis thermoelectric power is derived in connection with ρ
c in the low stage compounds.
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Takeshi Usuki
1993 Volume 62 Issue 2 Pages
634-638
Published: February 15, 1993
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Electronic and ionic conductivities of liquid Tl–Se alloys have separately been measured as a function of concentration and temperature. The system shows a deep minimum in the electronic conductivity at the stoichiometric composition (Tl
2Se). A characteristic decay time which is calculated from the slope of the potential decay is found to decrease with temperature for the liquid Tl
2Se. An anomaly in the ionic conductivity around the composition Tl
2Se has been observed. A very unusual negative temperature dependence of the ionic conductivity has been confirmed at Tl-rich range beyond the composition Tl
2Se.
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Hirofumi Akiyama, Tatsuo Hashimoto, Tadaharu Shibuya, Keiichi Edagawa, ...
1993 Volume 62 Issue 2 Pages
639-646
Published: February 15, 1993
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The resistivity of Al–Pd–Mn icosahedral quasicrystals increases almost linearly with decreasing temperature, shows a maximum at a temperature (between 10 and 100 K) and then decreases in low Mn alloys (<9at%Mn), while in high Mn alloys (>9at%Mn) the resistivity increases again steeply at even lower temperatures. The resistivity at helium temperature varies from 1500 to 9500 μΩ cm depending on the composition and quasicrystallinity of the sample. The magnetoresistance in single-grained sample of Al
70Pd
21Mn
9 is positive and temperature dependent, with
Δρ⁄ρ at 0.5 K at 8 T being as large as 6%. It is concluded that the temperature and magnetic-field dependences are governed dominantly by the weak localization effect for the case of strong spin-orbit scattering, and in high Mn concentration alloys, a Kondo effect superimposes to the weak localization effect.
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Hirohiko Sato, Norimichi Kojima, Kazuya Suzuki, Toshiaki Enoki
1993 Volume 62 Issue 2 Pages
647-658
Published: February 15, 1993
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K
3Cu
8S
6 is a two-dimensional metal which has two phase transitions at
T1 (153 K) and
T2 (55 K), accompanied by an incommensurate and a commensurate superstructure, respectively. In order to investigate these phase transitions, the mixed crystals (K
1−xRb
x)
3Cu
8S
6 have been synthesized and the effect of the alkali substitution and that of pressure have been studied by the measurements of their transport properties. With increasing
x,
T1 significantly decreases, reaching
T1 of Rb
3Cu
8S
6 (=110 K). Pressure also reduces
T1 of K
3Cu
8S
6 and Rb
3Cu
8S
6. On the other hand, the
T2 transition becomes obscure with increasing
x, and disappears thoroughly for
x≥0.50. In Rb
3Cu
8S
6, the
T2 transition is absent at ambient pressure but induced by the pressure of at most 0.5 GPa. Around
x=0.06, a remarkable rise in the resistivity appears below
T2. Its mechanism is discussed.
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Mahito Kohmoto
1993 Volume 62 Issue 2 Pages
659-663
Published: February 15, 1993
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Berry recognized in quantum mechanics a topological phase factor arising from the adiabatic transport of a system around a closed loop, which is essentially the Aharonov-Bohm effect in parameter space. In this paper we consider noninteracting electrons in a periodic potential in the presence of electromagnetic fields. The electric field is represented by a time-dependent vector potential. Adiabatic processes move states along a non-contractible closed loop in the magnetic Brillouin zone which is a torus. The existence of Berry’s phases in such processes is shown. A relation with the quantized Hall effect is discussed.
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Yoshio Nogami, Motoji Yamashita, Hiroshi Kaneko, Takehiko Ishiguro, Ak ...
1993 Volume 62 Issue 2 Pages
664-671
Published: February 15, 1993
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Non-ohmic behaviors under high electric field were investigated for highly conducting iodine-doped polyacetylene at different temperatures. The field dependence was enhanced with decrease of measuring temperature and conductivity. Through systematic numerical analysis we show that the high-field characteristics at different temperatures cannot be described consistently by Sheng model which has been utilized for analyzing the temperature dependence of conventional polyacetylene.
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Haruhisa Toyoda, Akihiko Sumiyama, Yasukage Oda, Kunisuke Asayama
1993 Volume 62 Issue 2 Pages
672-679
Published: February 15, 1993
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The proximity effect in Cu clad Nb wires of which Cu is doped with dilute magnetic impurities, has first been investigated in relation to the Kondo effect. As for Cu doped with dilute Fe, Co and Ni impurities, the probability of the spin flip scattering of conduction electrons, α, by Fe, Co and Ni impurities decreases linearly with decreasing temperature. As for Cu doped with dilute Mn impurities, the probability, α, by Mn impurities is concluded to be suppressed by the RKKY interaction between Mn impurities which depends on the electronic mean free path. The temperature dependence of the resistivity of the Mn alloy may be understood as a result of the coexistence of the dilute Kondo effect and the RKKY interaction between Mn impurities.
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Kazushige Machida, Toshimitsu Fujita, Tetsuo Ohmi
1993 Volume 62 Issue 2 Pages
680-689
Published: February 15, 1993
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In order to understand the phase diagram
H vs
T in UPt
3 the possible vortex structures are investigated theoretically. Our study is based on the pairing function which belongs to one-dimensional representation with odd-parity. In addition to the usual Abrikosov vortex two kinds of the non-trivial vortices are found where the multiple components of the pairing function are simultaneously non-vanishing. Each vortex solution corresponds to the triangular and square lattices. They should appear in a low field region (
H<0.1
Hc2) for the reasonable parameter values. Recent experiments on UPt
3, in particular, the small angle neutron experiment for the vortex structure investigations, are discussed in this connection.
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Kunitomo Hirai
1993 Volume 62 Issue 2 Pages
690-703
Published: February 15, 1993
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The spin density wave in chromium is discussed on the basis of electronic structure calculation. The electronic structure of sinusoidal spin density wave states with finite local magnetic moments is calculated for chromium by means of a tight-binding model Hamiltonian with a minimal basis set, which is obtained through some simplification to the first-principle LMTO method. The wave vector of the sinusoidal spin density wave state of lowest energy is found to be in good agreement with experiments for chromium and its alloys. Not only the amplitude of the fundamental wave of the spin density wave, but also that of the concomitant charge density wave and that of the third harmonic of the spin density wave are discussed.
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Makoto Honda
1993 Volume 62 Issue 2 Pages
704-716
Published: February 15, 1993
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High field magnetization of chromium trimers are discussed. The ground state crossover from the resultant spin
ST=1⁄2 to
ST=3⁄2 gives a step magnetization at low temperatures. However, the observed step shows a considerable smoothing than expected. The smoothing is satisfactorily explained by introducing Dzyaloshinsky-Moriya interaction which produces off-diagonal elements between the Kramers multiplets. The whole profiles of high field magnetization of two Cr-trimer complexes are calculated and the experimental results are well explained by the present model.
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Tetsufumi Tanamoto, Hiroshi Kohno, Hidetoshi Fukuyama
1993 Volume 62 Issue 2 Pages
717-730
Published: February 15, 1993
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Spin fluctuations in the extended
t-
J model have been investigated within the slave-boson mean-field approximation based on both uniform and singlet RVB states. By choosing the transfer integrals to reproduce the Fermi surface of LSCO and YBCO, we find that incommensurate spin fluctuations can be expected for the Fermi surface of LSCO-type, whereas only commensurate ones for that of YBCO-type, in agreement with experiments. Moreover effects of singlet RVB pairing have been explored and are shown to lead to the qualitative difference of the temperature dependences of the shift of nuclear magnetic resonance in the high and low doping regions as seen experimentally.
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