-
Alexander Bershadskii
Subject area: Classical and quantum physics: mechanics and fields.
1996 Volume 65 Issue 9 Pages
2739-2741
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The transport properties of particles (of passive scalar concentration) in random media with anomalous diffusion are studied. The generalized multifractal hypothesis of Havlin-Bunde: ‹ P
q › -- ‹ P ›
τ_q, , (τ_q -- q^γ, , γ < 1, , Physica 38D, 184, 1989), for probability density P(r, t) of the random walker is used to obtain the standard (scaling) multifractal exponent s_q in the limit γ → 1 (in the case for which this scaling exists). This limit corresponds to a phase transition from a random fractal structure to homogeneity (for homogeneous systems γ =1) and the standard (scaling) multifractality for concentration has the form ‹ {Θ}
R^q › -- R
-s_q, where {Θ}_R = ∫_v P(r, t) dv/v, , (v -- R^d is an arbitrary volume with scale R). It is shown that, in this limit, s_q = Aq, ln(q/q_o). The value q_0 = 2 can be obtained from the condition of compatibility between this approach and the generalized dimension description. Agreement between the theoretical results and experimental data is established.
View full abstract
-
Atsushi Mori, Minoru Maruyama, Yoshinori Furukawa
Subject area: Statistical physics and thermodynamics.
1996 Volume 65 Issue 9 Pages
2742-2744
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The Gibbs-Thomson equation thermodynamicallydescribes the melting point depression due to thecurvature of the interface. Usually this equation isexpressed as a 1st-order expansion with respect tothe curvature. We carry out the expansion up to2nd-order and apply it to calculate the melting pointdepression of an ice crystallite in water.
View full abstract
-
Toru Nakano, Toshiyuki Gotoh
Subject area: Fluid dynamics.
1996 Volume 65 Issue 9 Pages
2745-2748
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
We consider the anisotropic pressure effect on the interaction between the vorticity and strain field in the three-dimensional incompressible Euler equation. Vieillefosse showedthat the derivatives of the velocity field diverge spontaneously in a finite time whenonly the isotropic pressure Hessian is taken into account. We extend his method to include theanisotropic pressure Hessian, which is expressed in a parameterized way, in order toinvestigate the stability against the spontaneous singularity in the parameter space. Twoparameter regions are identified: (1) the region where the divergence occurs in afinite time and (2) the region where the derivative fields increase only in apower law with time. The model is discussed in relation to the direct simulation of theEuler equation.
View full abstract
-
Kimitaka Itoh, Sanae –I. Itoh, Masatoshi Yagi, Atsushi Fukuyama
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 9 Pages
2749-2752
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Theory of current-diffusive interchange mode turbulence in plasmas in the presence of collisional transport is developed. Amplitude of stationary fluctuations is expressed in terms of the double-valued function of the pressure gradient. The backward bifurcation is shown to appear near the linear stability boundary. The subcritical nature of the turbulence is explicitly illustrated. The critical pressure gradient at which the transition from collisional transport to the turbulent one is to occur is predicted. This work provides a prototype of the transport theory for nonlinear-nonequilibrium systems.
View full abstract
-
Takashi Suzuki, Hiroshi Goshima, Shigenobu Sakita, Toshizo Fujita, Mas ...
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2753-2756
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Symmetrized elastic moduli of high-quality single-crystalline CeRu
2 have been measured between 2 and 300, K by means of an ultrasonic technique. Both transverse moduli (C
11-C
12)/2 and C
44 soften markedly from 300 to -- 20, K without structural transition. In contrast, the bulk modulus C
B shows a normal temperature dependence without softening. These results indicate that there exists a marked structural fluctuation corresponding to a pure transverse strain in the normal conducting state of CeRu
2. Our analysis, taking account of the deformation potential coupling, reveals that a narrow band with relatively high density of states at E
F is responsible for the huge lattice softening.
View full abstract
-
Yukio Yasui, Yoshiaki Kobayashi, Jun Takeda, Shin–ichi Shamoto, ...
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 9 Pages
2757-2760
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Electrical resistivities ρ of BaCo
1-xNi_xS_2, which has a layered structure and exhibits the Mott transition with varying x, have been found to be strongly sensitive to pressure over a very wide temperature region.The paramagnetic insulator state, which exists in the region of x<~0.15 above the Néel temperature T
N, exhibits a transition to a metallic state at a rather small value of applied pressure p.The temperature T
N, at which the resistivity ρ exhibits anomalous increase with decreasing T, rapidly decreases with increasing p and becomes zero at the critical value of p=p
c(x) (<~15, kbar for x≥q0.05).The paramagnetic state thus obtained exhibits roughly T^2-like dependence of the resistivity.The metal-insulator transition of the present system is known to be easily controlled by the external pressure.
View full abstract
-
J. S. Pan, X. Y. Huang, Y. D. Fan
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1996 Volume 65 Issue 9 Pages
2761-2763
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The electronic structures and cohesive properties of the L1
2 and D0
19 structures of the metastable Ni
3Mo crystalline phase have been studied using the first-principles linear muffin-tin orbital method. The total energy of this metastable crystalline phase is calculated as a function of the Wigner-Seitz radius. The predicted structure is in agreement with that observed experimentally and the calculated equilibrium lattice parameter agrees well with the experimental value. The electronic structure is used to determine the relative stability of different structures.
View full abstract
-
Masatomo Uehara, Takashi Nagata, Jun Akimitsu, Hiroki Takahashi, Nobuo ...
Subject area: Superconductivity.
1996 Volume 65 Issue 9 Pages
2764-2767
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
We have observed superconductivity in the ladder material Sr
0.4Ca
13.6Cu
24O
41.84 under pressures of 3, GPa and 4.5, GPa by means of electrical measurements. The superconducting transition temperatures T
c (onset) are 12, K and 9, K at 3 and 4.5, GPa, respectively. The superconducting volume fraction was obtained to be about 5\under 3.5, GPa at 4.2, K, indicating the bulk nature of the superconductivity in this system.
View full abstract
-
Takayuki Goto, Takao Watanabe, Kyoichi Kinoshita, Azusa Matsuda, Masaf ...
Subject area: Superconductivity.
1996 Volume 65 Issue 9 Pages
2768-2771
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The temperature dependence of the
63/65Cu-NMR relaxation rate T
1-1 and the spectrum of the lightly doped high-T
c cuprate La_{1.89Ca
1.11Cu
2O
6+δ} (La2126) with bilayer CuO planes have been studied.The field-swept spectrum was explained by assuming that there are two Cu sites with quadrupole frequencies of
63ν
Q = 25.6 and 32 MHz. The Knight shift decreased monotonically with decreasing temperature in the normal state, which is consistent with the reported result that the system belongs to the lightly doped region where the hole content is less than the optimum value.The Curie-Weiss temperature dependence of (T
1T)
-1= 2600/(T+110) (K· s)
-1 in the normal state down to T
c indicates that the pseudo-spin gap does not always exist in lightly doped bilayer systems.
View full abstract
-
Koichi Kusakabe, Hideo Aoki
Subject area: Superconductivity.
1996 Volume 65 Issue 9 Pages
2772-2775
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Inspired by Sutherland's work [Phys. Rev. Lett. 74 (1995) 816] on the detection of bound spin waves, we propose that bound electron states can be detected from the dependence of interacting electron systems on the Aharonov-Bohm flux in the `extended zone' scheme, where the electron pairing halves the original period of N_a flux quanta in a system of linear size N_a. Along with the Bethe ansatz analysis, a numerical implementation for keeping track of the adiabatic flow of energy levels is applied to the attractive/repulsive Hubbard model and the t-J ladder.
View full abstract
-
Satoru Maegawa, Masahide Nishiyama, Nobuyuki Tanaka, Akira Oyamada, Mi ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2776-2778
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Successive magnetic phase transitions were found in the Kagomé lattice antiferromagnets RFe
3(OH)
6(SO
4)
2 [R=NH
4, Na, K]. The temperature dependence of the susceptibility has two cusps around 60, K for each compound. The X-ray diffraction patterns and the quadrupole resonance spectra show that the transitions are not caused by a structural change. The presence of these transitions was confirmed by NMR experiments. The NMR spectra show the development of magnetic ordering below the upper transition temperature. In the low-temperature phase the nuclear magnetization does not relax exponentially, which may suggest a domain structure of 120° spin structure due to degeneracy on the Kagomé lattice. The successive transitions may be caused by a small Ising-like anisotropy in the Heisenberg antiferromagnet.
View full abstract
-
Hiroyuki Nakamura, Fumikazu Takayanagi, Masayuki Shiga, Masakazu Nishi ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2779-2782
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The scattering of polarized neutrons has been measured in order to study the spin dynamics in Y
0.97Sc
0.03Mn
2 and Y
0.97Sc
0.03(Mn
0.9Al
0.1)
2. A large magnetic scattering peak observed at around Q=1.6, Å
-1 indicates the existence of strong antiferromagnetic spin fluctuations. The energy and Q spectra obtained at 290, K exhibit nearly the same profiles for both samples, while those obtained at low temperatures are quite different; for Y(Sc)Mn
2 the intensity and the energy width decrease only slightly with decreasing temperature and the intrinsic width remains finite (2Γ=20± 5, meV) at the lowest temperature (10K), whereas for Y(Sc)(Mn
0.9Al
0.1)
2, the intensity increases rapidly due to narrowing of the energy spectrum to the resolution limit (2Γ_res=5.8meV) at 10K, and instead, diffuse scattering was clearly observed at positions corresponding to the magnetic Bragg peaks of YMn
2, implying a slowing down of spin fluctuations and the presence of short range magnetic order at the low temperature. These results are discussed in terms of a spin-liquid to spin-glass transition caused by Al substitution.
View full abstract
-
Kanji Takehana, Mitsutake Oshikiri, Giyuu Kido, Masashi Hase, Kunimits ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2783-2785
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The magnetostriction and thermal expansion of CuGeO
3 have been measured in magnetic fields of up to 14, T using a capacitance method. An anomalous increase and hysteresis were observed in the magnetostriction at the transition between the spin-Peierls (SP) phase and the magnetic (M) phase, which show that the strain introduced at the transition from the uniform (U) phase to the SP phase is partially removed at the transition from the SP phase to the M phase.
View full abstract
-
Makoto Aikawa, Seishi Takagi, Masakazu Ito, Kazuyoshi Takeda, Hiroyuki ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2786-2789
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Susceptibility and magnetization measurements on the diluted Haldane system (CH
3)
4NNi
1-xZn_x(NO
2)
3 (Zn-doped TMNIN) have been carried out using a SQUID magnetometer. The contribution of edge moments in Ni
2+ chains is extracted from the experimental data using the formula employed in the quantum Monte Carlo calculation by Yamamoto and Miyashita (Phys. Rev. B 50 (1994) 6277). In the temperature range 5, K<T<15, K the Curie-like susceptibility of the edge moments shifts from the curve for two effective S=1/2 moments to the curve for one effective S=1 moment as the temperature is increased. Magnetization curves of pure and Zn-doped TMNIN are compared with the calculated ones for periodic and open chains at various temperatures. The crossover behavior is also observed in the temperature dependence of the magnetization curves of edge moments.
View full abstract
-
Masanori Cho, Hirohumi Sakashita
Subject area: Physical chemistry.
1996 Volume 65 Issue 9 Pages
2790-2792
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Quasi-elastic light scattering measurements have been made on gelatin solution in the temperature range that includes the sol-gel transition. Two decay modes were observed in the whole temperature region, even in the gel phase. The temperature dependence of the decay constant of each decay mode was obtained.Each decay constant shows an anomaly around the sol-gel transition point.In particular, it is found that the decay constant of the slow mode decreases to almost zero near the transition temperature in both phases.
View full abstract
-
Yoshihiro Ishibashi, Minoru Fukui
Subject area: Other areas of research of general interest to physicists.
1996 Volume 65 Issue 9 Pages
2793-2795
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Traffic flow on two one-dimensional roads with a crossing is analyzed using a cellular automaton model. A new phase diagram different from that proposed by Nagatani [J. Phys. A 26 (1993) 6625] has been obtained, which contains five phases. The configurations of cars in the phases I--V are discussed.
View full abstract
-
Satoshi Tsujimoto, Ryogo Hirota
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 9 Pages
2797-2806
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A discrete BKP hierarchy in bilinear form is given.It is shown that the solutions of thebilinear forms are given in terms of pfaffians and the bilinear equations of a discrete BKP hierarchy are reduced to an identity of pfaffians. The N-soliton solution is explicitly constructed in terms of the pfaffian.As an example of nonlinear difference equations, a difference analogueof the Sawada-Kotera equation is given from the discrete BKP hierarchy.
View full abstract
-
Xi–Wen Guan, Dian–Min Tong, Huan–Qiang Zhou
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 9 Pages
2807-2810
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The Lax pair for the one-dimensionalHeisenberg XYZ open chain is explicitly constructed. Our construction providesan alternative and direct demonstration for the quantum integrability of thesystem.
View full abstract
-
Norio Ohtomo, Ayako Sumi, Yukio Tanaka, Kazuo Tokiwano, Saburou Terach ...
Subject area: Statistical physics and thermodynamics.
1996 Volume 65 Issue 9 Pages
2811-2823
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Power spectral densities (PSD's) calculated by the maximum entropy method (MEM) for Rossler system indicated exponential decay with a large number of well-defined spectral lines. The spectral lines were confirmed to indicate a complete bifurcation up to the fifth-order period-doubling. An extremely anomalous behavior was recognized in the region of c=4.18--4.21 which is considered to be a transition region. The contribution of the power of the fundamental mode to the total power was overwhelmingly large: it becomes larger than 90\including chaotic ones was performed and the satisfactory results obtained. It will be discussed that the fluctuations due to amplitude instability of time series in the periodic solutions generate, resulting in the continuous component of PSD structured through the subharmonic cascade process, and this continuous region is restructured in the inverse cascade process (the socalled broad continuum in the chaotic mixing).
View full abstract
-
Takahiro Fukui, Norio Kawakami
Subject area: Statistical physics and thermodynamics.
1996 Volume 65 Issue 9 Pages
2824-2829
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
We study the Heisenberg spin chain with twisted boundary conditions, focusing on the adiabatic flow of the energy spectrumas a function of the twist angle. In terms of effective field theory for the nearest-neighbor model, we show that the period 2 (in unit 2π) obtained by Sutherland and Shastry arises from irrelevant perturbations around the massless fixed point, and that this period may be rather general for one-dimensional interacting lattice models at half filling. In contrast, the period for the Haldane-Shastry spin model with 1/r^2 interaction has a different and unique origin for the period, namely, it reflects fractional statistics in Haldane's sense.
View full abstract
-
Kyuichi Yasui
Subject area: Fluid dynamics.
1996 Volume 65 Issue 9 Pages
2830-2840
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The liquid temperature at bubble wall (T
L, i)is numerically calculated, including effect of the thermal conduction and that of the latent heatof non-equilibrium evaporation and condensationat the bubble wall under a condition of the picosecond sonoluminescence and that of nonlight-emission.It is concluded that T
L, i is almost identical to the ambient liquid temperature during bubble oscillations except at strong collapses.At strong collapses, T
L, i increases to the same order ofmagnitude with that of the maximum temperature attained in the bubble.It is mainly due to the thermal conduction from the heated interiorof the bubble.It is clarified that the energy given to the surrounding liquid by the latent heat of vapor condensation from the time of the maximum bubble radius to that of the minimumradius is comparable to or more than that by the thermal conduction, though the latent heat does not contribute much to the increase of T
L, i at the final stage of the strong collapse.
View full abstract
-
Makoto Okamura
Subject area: Fluid dynamics.
1996 Volume 65 Issue 9 Pages
2841-2845
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Weakly and fully nonlinear short-crested wavesnear the standing-wave limit are investigated.We clarify the relation between a standing wave solutionand a standing-wave limit solution of the short-crested waveanalytically and numerically.It is found that the short-crested wave cannot be continued analytically into the standing wave because of harmonic resonances.
View full abstract
-
Mamoru Shoji, Yousuke Nakashima, Kiyoshi Yatsu, Katsuhiko Tsuchiya, Yu ...
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 9 Pages
2846-2851
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
This paper describes a modified method of analysis of the charge exchange neutrals for determination of the radial profile of ion temperature including the effect of the ion finite Larmor radius. It also includes the effect of the charge exchange reaction with neutral hydrogen molecules. The ICRF-heated plasmas in the central cell of the GAMMA10 tandem mirror were analyzed by taking into account these effects. The obtained energy spectra and the count-rate spatial profiles of charge exchange neutrals were consistent with the experimental results. The present method, thus, proved to be effective in determining the radial profile of ion temperature.
View full abstract
-
Yuichi Takaku, Shigeo Hamada
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 9 Pages
2852-2859
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A system of collisionless neutral gas contained in a rigid vessel is considered as a simple model of reflection of field-reversed configuration (FRC) plasma by a magnetic mirror. The rebound coefficient of the system is calculated as a function of the incident speed of the vessel normalized by the thermal velocity of the gas before reflection. The coefficient is compared with experimental data of FIX (Osaka U.) and FRX-C/T(Los Alamos N.L.). Agreement is good for this simple model. Interesting is that the rebound coefficient takes the smallest value (-- 0.365) as the incident speed tends to zero and approaches unity as it tends to infinity. This behavior is reverse to that expected for a system with collision dominated fluid instead of collisionless gas. By examining the rebound coefficient, therefore, it could be successfully infered whether the ion mean free path in each expeiment was longer or shorter than the plasma length.
View full abstract
-
Hiroaki Shoyama, Masayoshi Tanaka, Seiichiro Higashi, Yoshinobu Kawai, ...
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 9 Pages
2860-2866
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Stochastic acceleration of electrons trapped in an inhomegeneous magnetic field is observed. A right-hand circular polarized microwave is used to excite an electron cyclotron wave, and a plasma with a temperature ≤ 6 eV and a density ≤ 7 × 10
11 cm
-3 is produced. The electrons trapped in the weak mirror interact with the electron cyclotron wave in their bouncing motion, and are accelerated to a few tens of keV range, emitting soft X-rays by bremsstrahlung. A simple discrete map based on the bounce period is derived to analyze the wave-particle system, and is found to be reduced to the Fermi map. The experimental results are understood with a knowledge of numerical experiments on this map, and the upper limit of acceleration is determined by the upper boundary of the stochastic region in the phase space. The theoretical scaling of the maximum electron energy with respect to wave power shows a good agreement with the experimental results.
View full abstract
-
Katsuji Chiyoda
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 9 Pages
2867-2871
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The equilibrium configuration of a tokamak is analysedby the equilibrium equations derived for analysing a reversed field pinch (RFP).The expressions of the magnetic field and the toroidal shiftin the internal plasma region and the external vacuum region are obtained. The expressions in the vacuum region become the Shafranov's expressions, when the plasma-center coordinates is used.Discontinuities of the equilibrium quantities are considered.It is concluded that the equilibrium equations are applicablealso to the tokamak plasmaand that the difference of the equilibriabetween the tokamak and the RFP stems from the choices of the pressure and the toroidal current function.A feature of our theory is thatany ordering to the safety factor is not imposed.
View full abstract
-
Michael Hörnquist, Rolf Riklund
Subject area: Lattice dynamics and crystal statistics.
1996 Volume 65 Issue 9 Pages
2872-2879
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
We investigate numerically how a solitary wave propagates insome one-dimensional diatomic periodic andaperiodic Toda lattices. It is found that a nearly stable waveof rather high amplitude can propagate in the periodic lattice.For several of the deterministic aperiodic sequences considered, the damping of the wave in the corresponding lattice is considerable less than for a random lattice.The short range correlation between the atoms in the aperiodic lattices seems to be of main importance for how much thewave is damped.We suggest therefore that the entropy according to Shannon mightbe a relevant measure for the properties of the lattices in this case. It is shown that this measure yields at least an approximativeagreement with what is actually achieved by our numerical experiments.It is also shown that the earlier proposed idea of viewing the process as multiplescattering cannot be applied to other cases than random sequenceswith small mass-differences.
View full abstract
-
Tomonori Koda, Hatsuo Kimura
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 9 Pages
2880-2888
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The head-tail asymmetry is distinction between energy of a pair of rod-like molecules in head-to-head configuration and energy of the pair in tail-to-tail or head-to-tail configuration.We use a molecular model system to consider arole of the head-tail asymmetry for the phase transitions of chiral smectics.Mean field theory indicates that our model system shows the existence of various types of intermediate phases such as Sm-C
*γ and AF phase betweenantiferroelectric Sm-C
*A phase and ferroelectricSm-C
* phase.One of origins of the existence of the intermediate phasesis the ordering of heads which induce interactions betweenseparated smectic layers.
View full abstract
-
Tomohei Sasada
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 9 Pages
2889-2894
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A study is made of the sine-Gordon model with random amplitudebearing the lattice pinning potential and the random pinningpotential, using the variational-replica method developed byM\acute{e}zard and Parisi. We find the existence of the criticalstrength of disorder below which the long-range translationalorder of the lattice is maintained and above which thereplica-symmetry is broken. It is shown that thereplica-symmetry breaking leads to the vanishing of the mass dueto the lattice pinning potential. A phase diagram in thetemperature-disorder plane is discussed.
View full abstract
-
Toshihiko Maeda, Masao Doi
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 9 Pages
2895-2899
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A new Monte Carlo method is proposed which predicts the isotropic-nematic transition of liquid crystalline molecules with complex molecular structure.The method utilizes a mean field theoryand calculates the free energy and the mean fieldpotential for given molecular structure and interaction potential. As an example, the isotropic-nematic transition of a rigid molecule with zigzag shape is studied andan even-odd effect in the isotropic-nematic transition is demonstrated.
View full abstract
-
Makoto Iwata, Yoshihiro Ishibashi
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 9 Pages
2900-2903
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The order parameters and the dielectric susceptibility in successive phase transitions in betaine phosphate were studied on the basis of the Landau-type thermodynamic potential proposed by Hara et al. [J. Phys. Soc. Jpn. 58 (1989) 4215]. It has been confirmed that the proposed thermodynamic potential reproduces well the temperature dependences of the order parameters and the dielectric susceptibility.
View full abstract
-
Mamoru Yamashita
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 9 Pages
2904-2909
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A model with a freedom of molecular sense has been proposed recently for the purpose to certify the assumptions in the ANNNI model with the third nearest neighbour interaction for successive phase transitions in ferroelectric smectics. The phase diagram of that model at the absolute zero temperature and orderings of the sense of molecular long axis are examined to clarify the mechanism to stabilise the ferrielectric phase (SmC
*γ) and the intermediate antiferroelectric phase (AF) appearing in such phase transitions. These phases are shown to be stable in certain area on a parameter space, which coincides qualitatively with the results based on the ANNNI model and consequently justifies the minimal theory carried out previously in which negative definiteness of the second nearest neighbour interaction and the existence of the third nearest neighbour one (or, positiveness) are certified.
View full abstract
-
Takashi Ikeda
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2910-2916
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The singularity index α for the asymmetry of X-ray photoemission core lines for Ag 3d statesis estimated by using the DV-Xα cluster method.The Friedel's phase shifts are obtained by calculating the local partial charge classified by an irreducible representation of the point group.The theoretical value of the singularity index α successfully reproduces the small experimental value if we extend the present result of finite size of clusters to an infinite one.
View full abstract
-
Satoru Ohno, Yuka Mizushina, Tatsuya Okada
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2917-2921
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The dependence of magnetic susceptibility on composition for liquid Ge
1-cSe
c alloys exhibits a broad minimum around the composition c = 0.72 in the temperature range of 1023--1223, K. At higher temperatures, the broad minimum moves to the composition c = 0.5. The exponential temperature dependence of paramagnetic susceptibility on the Se-rich side can be explained by the formation of the Curie-like spin states. The movement of broad minimum is caused by a rapid increase in the Curie-like spin states with increasing temperature. The paramagnetic susceptibility on the Ge-rich side depends mainly on the density of states at the Fermi level.
View full abstract
-
Takashi Hotta, Yasutami Takada
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2922-2935
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
We make a careful perturbation analysis of the electronic self-energyΣ in terms of the effective electron hopping integral A in the infinite-dimensional system. We apply this formal analysis to the system in which the attractive interaction between electrons mediated by local optic phonons competeswith the electron-electron short-range repulsion. By summing the most divergent terms in Σ up to infinite order, we discuss the dynamical localization-delocalization transition.
View full abstract
-
Mitsutake Oshikiri, Kanji Takehana, Toshihisa Asano, Giyuu Kido
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2936-2939
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The cyclotron resonance of n-GaP, which has the camel's back structure in the conduction band around the X point, has been studied at a very wide far infrared region (119, 215, 433, 690, 1500, μ m) up to 30, T on an epitaxially grown single crystal. The values of the effective mass band parameter m
t, m
l, and the camel's back height ΔE have been determined by fitting cyclotron resonances around the magnetic break down point as well as in the high energy region to the Landau level energy structure. The k-linear term was added as a perturbation in the calculation. The results show that m
t=(0.251± 0.005)m
0, m
l=(0.90± 0.04)m
0 and ΔE=2.7± 0.1, meV.
View full abstract
-
Chikara Sugiura, Hiroharu Yorikawa, Shinji Muramatsu
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 9 Pages
2940-2945
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The phosphorus Kβ emissionfluorescence spectra from10 selected compounds are measured with a high-resolution two-crystalvacuum spectrometer. The phosphorus compounds studied include inorganiccompounds K
2HPO
3, NaH
2PO
2·H
2O, NaH
2PO
3·2.5H
2O, Ca
2P
2O
7, Cu
2P
2O
7 and (NaPO
3)
6; and organic compoundstri-o-tolylphosphine (o-CH
3C
6H
4)
3P, tri-m-tolylphosphine (m-CH
3C
6H
4)
3P, tri-p-tolylphosphine (p-CH
3C
6H
4)
3P andtriphenylphosphine oxide (C
6H
5)
3PO. The measured P Kβemission spectra are discussed in relation to chemical environmentsaround phosphorus atom in the compounds. It is shown that the P Kβemission spectra are strongly influenced by chemical environments. Theeffect of o-, m- and p-methyl substitution at the benzene ring(position isomerism) is observed in theemission spectra of tri-o-tolylphosphine, tri-m-tolylphosphineand tri-p-tolylphosphine.
View full abstract
-
Jun Takeda, Koji Fujiwara, Masatoshi Sato, Takashi Nishioka, Masaaki K ...
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 9 Pages
2946-2951
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Cu-site substitution effects on various quantities of high-T
c oxides have been investigated by using sintered sample series of La
1.92Sr
0.08Cu
1-xM_xO
4 (M=Mg, , Mn) and La
2-ySr_yCu
1-xM_xO
4 (M=Ti, , Co), where in the latter systems with trivalent impurity elements, (y-x) was fixed in each series to keep the carrier concentration to be constant. Results obtained previously for the sample series with M=Zn and Ni are also discussed for comparison. Hall coefficients R
H and thermoelectric powers S are enhanced by magnetic impurities, while all the nonmagnetic impurities suppress them almost equally. Substitution effects of Co which undergoes the low spin-high spin crossover with increasing temperature, can also be understood by this framework. The results indicate importance of the magnetic correlation for the behavior of R
H and S.
View full abstract
-
Mikio Eto
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 9 Pages
2952-2962
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Nonequilibrium transport properties are studied in one-dimensionalarrays of metallic quantum dots connected in series, taking account ofthe long-range charging effect.The current and its fluctuation are calculated by solving theMaster equation and by performing the Monte Carlo simulation.When the array is smaller than the interaction range, charges can be transported, one by one, at low bias voltages.The transport properties have rich structures, reflecting a regular or irregular motion of charges, as functions of the gate voltage.When the array is larger than the interaction range, more than one charges move collectively due to the interaction witheach other. The correlation results in a large peak in thecurrent fluctuation spectrum.With increasing bias voltage, the characteristic features disappear, and the current fluctuation goes to a constant level which is 1/(N+1) of the classical shot noise, in an array of N dots.
View full abstract
-
Takeo Kato, Masatoshi Imada
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1996 Volume 65 Issue 9 Pages
2963-2975
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Macroscopic quantum tunneling (MQT) for a single fluxon moving along a long Josephson junction is studied theoretically.To introduce a fluxon-pinning force, we consider inhomogeneities made by modifying thickness of an insulating layer locally.Two different situations are studied: one is the quantum tunnelingfrom a metastable state caused by a single inhomogeneity, and the otheris the quantum tunneling in a two-state system made by two inhomogeneities.In the quantum tunneling from a metastable state, the decay rate is estimated within the WKB approximation. Dissipation effects on a fluxon dynamics aretaken into account by the Caldeira-Leggett theory. We propose a device to observe quantum tunnelingof a fluxon experimentally. Required experimental resolutionsto observe MQT of a fluxon seem attainablewithin the presently available micro-fabrication technique.For the two-state system, we studyquantum resonance between two stable states, i.e., macroscopic quantum coherence (MQC). From the estimate for dissipation coefficients due to quasiparticletunneling, the observation of MQC appears to be possible within theCaldeira-Leggett theory.
View full abstract
-
Hiroshi Ajiki, Tsuneya Ando
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1996 Volume 65 Issue 9 Pages
2976-2986
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A lattice instability of carbon nanotubes induced by a magnetic field perpendicular to the tube axis is studied in a k·p scheme.Both in-plane Kekulé and out-of-plane distortions are enhanced drastically with increase of a magnetic field independent of whether a nanotube is metallic or semiconducting and magnetic flux passing through the cross section of a nanotube.The distortions become dependent on the position in the circumference direction.
View full abstract
-
Hiroshi Ito, Takehiko Ishiguro, Masahiro Kubota, Gunzi Saito
Subject area: Superconductivity.
1996 Volume 65 Issue 9 Pages
2987-2993
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The pressure phase diagram of κ-(BEDT-TTF)_2Cu[N(CN)_2]Cl is determined by measuring the intralayer and interlayer resistivities. With increase of pressure, nonmetallic behavior of resistivity is suppressed and a metallic phase is stabilized, yielding the phase reentrance near critical pressure region. Concurrently, an incomplete superconductivity phase appearing at ambient pressure becomes to show complete superconductivity giving zero resistance when the sheet resistance becomes comparable to h/4e^2 by the application of pressure, indicating that the superconductivity is localized in the lower pressure region. The effect of deuteration of BEDT-TTF molecule on the pressure phase diagram is also discussed.
View full abstract
-
Yuuichi Tazuke, Fumihiro Matsukura
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2994-2997
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The ac-susceptibility of a three-dimensional Ising spin glass Fe
0.05TiS
2 is analyzed above its spin glass transition temperature, in order to determine a distribution function g(ln τ ) of spin relaxation times τ . The probable function consists of a constant part at short times and a decreasing part at long times with a sudden cut-off. This form is consistent with g(ln τ ) simulated and attributed to be a spin glass critical dynamics by Takayama. There remain small disagreements between the data and the calculated values, suggesting the existence of a tail extending from the long-time end of the distribution function.
View full abstract
-
Masaaki Yamaguchi, Tomoki Furuta, Masayasu Ishikawa
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
2998-3006
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
By means of specific heat and magnetic susceptibility measurements we investigated the magnetic compounds of various crystal structure, CuWO
4, LiCuVO
4, CuSb
2O
6, CuNb
2O
6 and CuBi
2O
4. All of these cuprates revealed strong one-dimensional (1D) correlations persisting up to very high temperatures which are well explained by the S=1/2 Heisenberg antiferromagnetic linear-chain model. At lower temperatures they showed various long-range magnetic ordering except for CuNb
2O
6. In particular, we observed a rather unusual transition at 2.4, K for LiCuVO
4 which is conjectured to be a transition to the S=1/2 quadratic Ising antiferromagnet, thereby demonstrating a dimensional cross-over of correlations from 1D to 2D. The magnetic susceptibility and specific heat exhibit a critical point and a logarithmic divergence at 2.4, K, respectively, as predicted by theory. We herein report the experimental results and the preliminary analyses of these low-dimensional cuprates.
View full abstract
-
Mikito Koga, Hiroyuki Shiba
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
3007-3015
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
The Kondo effect due to (5f)
2 impurities is studied by restricting thef-electron states to a non-Kramers doublet and a singlet in a tetragonalor hexagonal crystal field.The singlet level plays an important role to stabilize the Fermi liquid overthe non-Fermi liquid.The nature of the Fermi-liquid fixed point, which results from the numericalrenormalization group calculation, is analyzed.It has turned out to be different from the standard one because of a combinedeffect of two types of local singlets.One is due to the crystal field and the other is due to the Kondo effect.The leading irrelevant interaction near the fixed point is of the Coulomb type, whose couplings depend on the orbital channels of conduction electrons.
View full abstract
-
Isao Harada, Tomoaki Suzuki, Akio Kotani
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
3016-3020
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
A mechanism is proposed for the magnetic circular X-ray dichroism (MCXD) at the pre-peak of the Fe K-edge in rare-earth iron garnets. It is found based on a cluster model that, at the pre-peak, the hybridization between the 3d state and the 4p state of an Fe ion on the tetrahedral site through the ligand 2p states is responsible for the weak electric-dipole absorption while the combined effect of the spin-orbit interaction and the spin polarization in the 3d states give rise to its MCXD. In addition, the configuration interaction is shown to be important in explaining the asymmetric dispersion-type MCXD spectra observed.The effects of the core hole as well as of the band character of the 4p states are discussed briefly in connection with MCXD observed in the main K-edge region.
View full abstract
-
Teruo Ono, Yasunari Sugita, Teruya Shinjo
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
3021-3024
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Magnetic viscosity of multilayer wires was investigated for the first time by measuring the giant magnetoresistance effect. Very small magnetization change, of the order of 10
-7, emu, could be detected by this method. The time dependence of magnetization showed that the thermal excitation mechanism is dominant down to 3K.
View full abstract
-
Takehiro Sakaguchi, Kazuhisa Kakurai, Tetsuya Yokoo, Jun Akimitsu
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
3025-3031
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Magnetic excitations of the ideal one-dimensional, spin S=1, antiferromagnet Y
2BaNiO
5 are studied by means of inelastic neutron scattering on single crystal sample. Our experimental results at low temperature indicate that Y
2BaNiO
5 can be regarded as the best isotropic Haldane-system sofar studied with the intrachain exchange energy J/k
B=-24.1, meV and the averaged gap Δ(T=7, K)=8.5, meV. Y
2BaNiO
5 exhibits a good magnetic one-dimensionality with the inter-/intrachain exchange ratio of |J
′/J|≤ 10
-4 and has only very small easy-axis and in-plane single ion anisotropy of |D/J|=0.03 and |E/J|-- 0.01. In addition the temperature dependence of the Haldane gap Δ(T) and its damping rate was determined.
View full abstract
-
Hiroaki Kusunose, Kazumasa Miyake
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 9 Pages
3032-3042
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
It is shown on the basis of the multiplicative renormalization-group method oftwo-loop order that the low-energy effective Hamiltonian of a stronglycoupled localelectron-phonon system is mapped to the two-channel Kondo model.A phonon is treated as an Einstein oscillator with restricted Hilbertspace such that up to one-phonon process is taken into account.By eliminating the high energy process of conduction electrons, it is shownthat a certain class of couplings between ion vibrations and conductionelectrons is selectively grown up. As a result the system is reduced to thetwo-channel Kondo model.The crossover temperature T
K and the renormalized phonon frequency Δ
x are expressed in terms of the mass ratio m/M, m and Mbeing the mass of electron and ion, and the electron-phonon couplingg/D, D being half the bandwidth of conduction electrons.The anomalous behaviors associated with thisrenormalization can be mesuarable if the condition T
K>Δ
x isfulfilled. It is demonstrated that such condition is satisfied when g/D issufficiently large but in a realistic range.
View full abstract
-
Atsushi Goto, Hiroshi Yasuoka, Yutaka Ueda
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1996 Volume 65 Issue 9 Pages
3043-3048
Published: September 01, 1996
Released on J-STAGE: October 01, 1999
JOURNAL
RESTRICTED ACCESS
Oxygen content (y) dependence of the NMR relaxation rates (1/T
1, 1/T
2G) of the Cu(2) site of YBa
2Cu
3O_y has been studied to investigate magnetic and spin pseudo-gap phase diagrams of this system. The characteristic spin gap temperature (T
sg) defined by the peak position of (1/T
1T) has a plateau as a function of oxygen content (y), at y-- 6.6, so-called “60K” phase where T
c also has a plateau. This plateau means that T
sg may be a monotonic function of hole concentration. On the other hand, it has been confirmed from the Curie-Weiss T-dependence of T
2G2 well above T
sg that the “Weiss Temperature (Θ)” for χ (Q) changes its sign from negative to positive at y-- 6.85. This means that, unless the spin gap and the superconductivity occurred, the real ground state would change from the weak antiferromagnetic metallic state to the nearly antiferromagnetic one at y-- 6.85, which is far from the real critical point, y=6.42.
View full abstract