Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 65, Issue 9
Displaying 1-50 of 63 articles from this issue
  • 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
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    The transport properties of particles (of passive scalar concentration) in random media with anomalous diffusion are studied. The generalized multifractal hypothesis of Havlin-Bunde: ‹ Pq › -- ‹ 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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    Symmetrized elastic moduli of high-quality single-crystalline CeRu2 have been measured between 2 and 300, K by means of an ultrasonic technique. Both transverse moduli (C11-C12)/2 and C44 soften markedly from 300 to -- 20, K without structural transition. In contrast, the bulk modulus CB 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 CeRu2. Our analysis, taking account of the deformation potential coupling, reveals that a narrow band with relatively high density of states at EF is responsible for the huge lattice softening.
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  • 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
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    Electrical resistivities ρ of BaCo1-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 TN, exhibits a transition to a metallic state at a rather small value of applied pressure p.The temperature TN, 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=pc(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.
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  • 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
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    The electronic structures and cohesive properties of the L12 and D019 structures of the metastable Ni3Mo 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.
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  • 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
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    We have observed superconductivity in the ladder material Sr0.4Ca13.6Cu24O41.84 under pressures of 3, GPa and 4.5, GPa by means of electrical measurements. The superconducting transition temperatures Tc (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.
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  • 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
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    The temperature dependence of the 63/65Cu-NMR relaxation rate T1-1 and the spectrum of the lightly doped high-Tc cuprate La_{1.89Ca1.11Cu2O6+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 63νQ = 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 (T1T)-1= 2600/(T+110) (K· s)-1 in the normal state down to Tc indicates that the pseudo-spin gap does not always exist in lightly doped bilayer systems.
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  • 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
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    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.
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  • 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
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    Successive magnetic phase transitions were found in the Kagomé lattice antiferromagnets RFe3(OH)6(SO4)2 [R=NH4, 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.
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  • 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
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    The scattering of polarized neutrons has been measured in order to study the spin dynamics in Y0.97Sc0.03Mn2 and Y0.97Sc0.03(Mn0.9Al0.1)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)Mn2 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)(Mn0.9Al0.1)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 YMn2, 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.
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  • 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
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    The magnetostriction and thermal expansion of CuGeO3 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.
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  • 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
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    Susceptibility and magnetization measurements on the diluted Haldane system (CH3)4NNi1-xZn_x(NO2)3 (Zn-doped TMNIN) have been carried out using a SQUID magnetometer. The contribution of edge moments in Ni2+ 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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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).
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  • 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
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    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.
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  • 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
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    The liquid temperature at bubble wall (TL, 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 TL, i is almost identical to the ambient liquid temperature during bubble oscillations except at strong collapses.At strong collapses, TL, 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 TL, i at the final stage of the strong collapse.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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 × 1011 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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    The dependence of magnetic susceptibility on composition for liquid Ge1-cSec 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.
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  • 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
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    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.
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  • 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
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    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 mt, ml, 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 mt=(0.251± 0.005)m0, ml=(0.90± 0.04)m0 and ΔE=2.7± 0.1, meV.
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  • 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
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    The phosphorus Kβ emissionfluorescence spectra from10 selected compounds are measured with a high-resolution two-crystalvacuum spectrometer. The phosphorus compounds studied include inorganiccompounds K2HPO3, NaH2PO2·H2O, NaH2PO3·2.5H2O, Ca2P2O7, Cu2P2O7 and (NaPO3)6; and organic compoundstri-o-tolylphosphine (o-CH3C6H4)3P, tri-m-tolylphosphine (m-CH3C6H4)3P, tri-p-tolylphosphine (p-CH3C6H4)3P andtriphenylphosphine oxide (C6H5)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.
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  • 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
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    Cu-site substitution effects on various quantities of high-Tc oxides have been investigated by using sintered sample series of La1.92Sr0.08Cu1-xM_xO4 (M=Mg, , Mn) and La2-ySr_yCu1-xM_xO4 (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 RH 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 RH and S.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    The ac-susceptibility of a three-dimensional Ising spin glass Fe0.05TiS2 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.
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  • 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
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    By means of specific heat and magnetic susceptibility measurements we investigated the magnetic compounds of various crystal structure, CuWO4, LiCuVO4, CuSb2O6, CuNb2O6 and CuBi2O4. 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 CuNb2O6. In particular, we observed a rather unusual transition at 2.4, K for LiCuVO4 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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    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.
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  • 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
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    Magnetic excitations of the ideal one-dimensional, spin S=1, antiferromagnet Y2BaNiO5 are studied by means of inelastic neutron scattering on single crystal sample. Our experimental results at low temperature indicate that Y2BaNiO5 can be regarded as the best isotropic Haldane-system sofar studied with the intrachain exchange energy J/kB=-24.1, meV and the averaged gap Δ(T=7, K)=8.5, meV. Y2BaNiO5 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.
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  • 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
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    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 TK and the renormalized phonon frequency Δx 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 TKx isfulfilled. It is demonstrated that such condition is satisfied when g/D issufficiently large but in a realistic range.
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  • 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
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    Oxygen content (y) dependence of the NMR relaxation rates (1/T1, 1/T2G) of the Cu(2) site of YBa2Cu3O_y has been studied to investigate magnetic and spin pseudo-gap phase diagrams of this system. The characteristic spin gap temperature (Tsg) defined by the peak position of (1/T1T) has a plateau as a function of oxygen content (y), at y-- 6.6, so-called “60K” phase where Tc also has a plateau. This plateau means that Tsg may be a monotonic function of hole concentration. On the other hand, it has been confirmed from the Curie-Weiss T-dependence of T2G2 well above Tsg 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.
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