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Volume 61, Issue 9
Displaying 1-50 of 60 articles from this issue
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Masuo Suzuki1992 Volume 61 Issue 9 Pages 3015-3019
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA general scheme to realize nonsymmetric higher-order decomposition of exponential operators and symplectic integrators is constructed. This gives a unified theory of the previous symmetric and nonsymmetric decomposition. Ruth’s nonsymmetric third-order real decomposition is shown to be a simple example of the present general theory.View full abstractDownload PDF (590K) -
Yoshifumi Sakamoto1992 Volume 61 Issue 9 Pages 3020-3023
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA method is presented to carry out molecular dynamics calculations with the optimized electron configuration at each time step and with the conservation of the total energy of the system of atoms. Although an example of calculations within the tight-binding approximation is presented, the method can also be used in ab initio calculations. A method to obtain each eigenstate of the one-electron hamiltonian by the use of the steepest-descent equation of motion is also presented. Moreover, a feature of the flow of the electron configuration in the configuration space which is governed by the steepest-descent equation of motion is discussed.View full abstractDownload PDF (524K) -
Masanori Aoki1992 Volume 61 Issue 9 Pages 3024-3026
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSVibrations of a perfect one-dimensional diatomic lattice which has quartic anharmonicity are investigated by computer simulation. We obtain a stationary localized mode which has the s-like symmetry. This self-localized mode appears above the optical band of the corresponding linear lattice.View full abstractDownload PDF (241K) -
Hidenori Hasimoto1992 Volume 61 Issue 9 Pages 3027-3029
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA theorem is presented which gives the perturbation pressure \ ildep(x) and velocity \ ildeu(x) directly when a sphere of unit radius r=1 with its center at the origin is introduced into an unlimited viscous fluid of viscosity μ obeying the Stokes equation, of which the pressure and the velocity are p(x) and u(x).
They are
(Remark: Graphics omitted.)
where ur is the radial velocity u·x⁄r, ω is the vorticity ∇×u, and the prime ′ is the radial derivative d⁄dr=(1⁄r)(x·∇), ∇⁄⁄ is the tangential gradient ∇−(x⁄r)(d⁄dr), and the asterisk * on f(x) denotes the inversion [f(x)]*=f(x⁄r2).View full abstractDownload PDF (229K) -
Shunjiro Shinohara, Ken-ichi Yamagishi, Satoshi Ohdachi, Akira Ejiri, ...1992 Volume 61 Issue 9 Pages 3030-3033
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe first boronization in a reversed field pinch machine has been carried out and its effects on plasma performance have been studied. From a residual gas analysis, it was found that total and partial pressures were reduced. During the first several tens of discharges, the mean plasma density normalized by a filling pressure became much higher and was nearly constant during a discharge, but these phenomena became weaker shot by shot. Radiated power, plasma resistance, CrI line intensity and high-frequency magnetic oscillations decreased. The ion temperature from Doppler broadening of the CV line changed only slightly, whereas lower temperature from the OV line was found.View full abstractDownload PDF (570K) -
Kunihiro Sato, Hideaki Katayama, Fujio Miyawaki1992 Volume 61 Issue 9 Pages 3034-3037
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSElectrostatic potential formed in a collisionless plasma flow near the magnetic throat is investigated by kinetic analysis under the condition that a particle source in a plasma can be neglected. It is found that the plasma flow is required to satisfy the generalized Bohm criterion at the throat for the formation of a stationary continuous potential, and then the speed of plasma flow must exceed the acoustic speed. A monotonical potential profile falling from the inside of the throat to the wall can build up only if the Bohm criterion is marginally satisfied at the throat.View full abstractDownload PDF (518K) -
Mieko Toida, Tian Xi Zhang, Yukiharu Ohsawa1992 Volume 61 Issue 9 Pages 3038-3041
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSIon orbits reflected by a magnetosonic wave are theoretically analyzed, and the conditions for ion reflection are derived. In a low beta case, the reflected ions can form a ring distribution in velocity space. The velocity and energy distribution functions of those particles are obtained.View full abstractDownload PDF (418K) -
Hiroyuki Mashiyama, Kousirou Sugimoto, Yasuaki Oohara, Hideki Yoshizaw ...1992 Volume 61 Issue 9 Pages 3042-3045
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe phase transition at T3=73.5 K in Rb2ZnCl4 is investigated by means of neutron scattering at JRR-3M(4G). In phase 4 below T3, superlattice reflections appear at the S-point, and their intensity increases continuously with decreasing temperature. The critical index β estimated from the superlattice intensity is 0.37. The extinction rule within the (h, k, 0) plane is consistent with the space group C1c1. Phonon dispersion of low energy is determined by inelastic scattering. Softening of the phonon branch is observed at the S-point as T3 is approached.View full abstractDownload PDF (467K) -
Hisatoshi Yokoyama, Yoshio Kuramoto1992 Volume 61 Issue 9 Pages 3046-3049
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA set of generalized Gutzwiller-type wave functions with spin and charge currents and/or spin polarization are shown to be exact eigenstates of the supersymmetric t-J-type model with long-range interactions. The increment of energy in the presence of currents is proportional to the square of the currents without any higher-order corrections for arbitrary size of the system. The exact excited states are identified by the absence of statistical fluctuations in the variational Monte Carlo calculation. The spin susceptibility is found to be independent of the size, as in the case of the charge susceptibility.View full abstractDownload PDF (460K) -
Hiroaki Yamada, Masaki Goda, Yoji Aizawa, Mitsusada Sano1992 Volume 61 Issue 9 Pages 3050-3053
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSDynamics of an electron in a tightly binding one-dimensional disordered system is studied numerically. The time evolution of wavepackets is traced by the time-dependent Schrödinger equation. The mean square displacement of the packet scaled by the localization length shows a universal time evolution from the ballistic regime to the localized regime in an ordinary disordered system. The time evolution in the modified Bernoulli systems with long-range structural correlation also shows the same universal diffusion.View full abstractDownload PDF (495K) -
Shigeki Ohsugi, Yoshio Kitaoka, Masafumi Kyogaku, Kenji Ishida, Kunisu ...1992 Volume 61 Issue 9 Pages 3054-3057
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe nuclear relaxation behavior in s-wave superconductors has been investigated as for Chevrel-phase superconductors, TlMo6Se7.5 and Sn1.1Mo6Se7.5 with Tc=12.2 K and 4.2 K, respectively. The nuclear-spin-lattice-relaxation rate, 1⁄T1, of 119Sn in Sn1.1Mo6Se7.5 reveals a distinct coherence peak just below Tc, followed by an exponential decrease with the isotropic energy gap of 2Δ=3.6 kBTc in a weak coupling regime. By contrast, 1⁄T1 of 205Tl in TlMo6Se7.5 possesses no coherence peak, although the exponential decrease of 1⁄T1 has also been observed with a somewhat larger value of 2Δ=4.5 kBTc in a strong coupling regime. The stronger electron-phonon coupling enhances the superconducting transition temperature and at the same time, opens a decay channel to cause an intense damping of quasiparticles, resulting in the depression of the coherence peak. The comparison with high-Tc superconductors will be discussed.View full abstractDownload PDF (583K) -
Isao Watanabe, Kenji Kawano, Ken-ichi Kumagai, Kusuo Nishiyama, Kaneta ...1992 Volume 61 Issue 9 Pages 3058-3061
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSPositive muon spin rotation (μ+SR) is applied to La2−xBaxCuO4 around x=0.12, where superconductivity is suppressed remarkably. The magnetic ordering of Cu-moments appears below 35 K in the narrow range of 0.11≤x≤0.135, where the transition from the low-temperature orthorhombic (LTO) to the low-temperature tetragonal (LTT) structure exists. The present study suggests strongly that the magnetic ordering of Cu-moments plays an important role in the suppression of the high-Tc superconductivity around x=0.12 in La2−xBaxCuO4.View full abstractDownload PDF (579K) -
Hikaru Kawamura1992 Volume 61 Issue 9 Pages 3062-3066
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe nearest-neighbor ±JXY (plane rotator) spin glass in three dimensions is studied by means of a Monte Carlo simulation, with a focus on its chiral ordering. Finite-size scaling analysis indicates that the chiral-glass transition takes place at a finite temperature with the associated exponents νc=1.5±0.3 and ηc=−0.4±0.2, whereas the conventional spin-glass ordering occurs only at zero temperature. The obtained chiral-glass exponents are close to the spin-glass exponents of a three-dimensional Ising spin glass.View full abstractDownload PDF (617K) -
Yuichiro Ishikawa, Koji Shigematsu1992 Volume 61 Issue 9 Pages 3067-3069
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSESR measurements have been made on a powder sample of Sr0.60Ca0.40CuO2 (the SrCuO2 structure) at room and liquid nitrogen temperatures. Its ESR spectrum consists of seven hyperfine lines associated with a pair of identical Cu ions. The hyperfine term in the spin Hamiltonian takes the form AS·(I1+I2), where A is a hyperfine constant; S the total electronic spin of a pair of Cu ions; and I1, I2 the nuclear spins of Cu ions. The spectroscopic splitting factor g=2.18, and |A|=72×10−4 cm−1. The spectrum indicates that a fine structure contributes to broadening hyperfine lines. At liquid nitrogen temperature, microwave absorption was detected over the complete range of a magnetic field sweep, being accompanied with the ESR absorption due to Cu ion pairs.View full abstractDownload PDF (314K) -
Kazuhiro Hikami, P. P. Kulish, Miki Wadati1992 Volume 61 Issue 9 Pages 3071-3076
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSPresented is a general method to construct quantum spin Hamiltonians with long-range pairwise interactions. The Hamiltonian is given explicitly in terms of the R-matrices on an inhomogeneous lattice. Applications to spin-1/2 chains, higher spin chains and Zn models are shown.View full abstractDownload PDF (492K) -
Takeshi Iizuka, Miki Wadati1992 Volume 61 Issue 9 Pages 3077-3085
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA new approach to nonlinear waves in one-dimensional discontinuous media is presented. As a model a nonlinear lattice which has a discontinuity of the mass distribution is considered. Two kinds of physically interesting waves, slowly varying waves and carrier wave modulations, are investigated. For the former (latter), incident, reflected and transmitted waves are described by Korteweg-de Veries (Nonlinear Schrödinger) equations on different coordinates. The reflected and transmitted waves are constructed from the incident wave analytically. Fission and reflection of a soliton due to the discontinuity are explicitly shown in the lowest order.View full abstractDownload PDF (844K) -
Yôhei Saika, Hidetoshi Nishimori1992 Volume 61 Issue 9 Pages 3086-3095
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWe examine the existence of long-range order in the two-dimensional frustrated XXZ model with next nearest neighbor interactions using the spin wave theory and the method of infrared bounds. The results show that the XY-like system may have essentially the same properties as the isotropic Heisenberg case, while the Ising-like system is very unlikely to show non-classical behavior. We also prove the absence of twisted order.View full abstractDownload PDF (929K) -
Junkichi Satsuma, Kenji Kajiwara, Junta Matsukidaira, Jarmo Hietarinta1992 Volume 61 Issue 9 Pages 3096-3102
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSSolutions of the Broer-Kaup system describing one-dimensional shallow water waves are discussed by using its trilinear form. It is shown that the soliton solutions have the interesting properties that (i) their speed is determined by a dispersion relation up to an overall constant, and (ii) there is a possibility of fusion and fission of solitons. These properties reflect the particular structure of the trilinear form.View full abstractDownload PDF (630K) -
R. E. Nettleton1992 Volume 61 Issue 9 Pages 3103-3113
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWith the aid of projection operators \hatP originally used by Zwanzig, phenomenological equations of irreversible thermodynamics can be derived from the Liouville equation. The phenomenological coefficients are expressed in terms of time correlations Lc(t) in which (1−\hatP)i\hatL replaces the Liouville operator \hatL in the formalism of Mori. Following a procedure of Lee, Lc is calculated via an expansion of time-dependent functions in orthogonal basis functions which are made finite in number by adjustment of \hatP. By this adjustment, one obtains a variety of analytical forms for Lc(t) which need not decay rapidly in order to yield phenomenological equations in Markovian form. Flexibility in \hatP can compensate for closure and Markovian approximations.View full abstractDownload PDF (1173K) -
Tsuyoshi Horiguchi, Ojiro Nagai, Seiji Miyashita, Yukio Miyatake, Yosh ...1992 Volume 61 Issue 9 Pages 3114-3124
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWe investigate low-temperature behaviors for an antiferromagnetic Ising model of infinite-spin on the triangular lattice. The internal energy, the specific heat, and the spontaneous sublattice-magnetizations are calculated by Monte Carlo simulations at low temperatures. The low-temperature expansions of the internal energy and the specific heat are obtained from a low-temperature expansion of the free energy and show excellent agreements with the results by the Monte Carlo simulations. The zero-temperature value of the specific heat is found to be equal to 2/3. The effects of the misfits of the first order are discussed.View full abstractDownload PDF (1186K) -
Kanpathipillai Murukesapillai1992 Volume 61 Issue 9 Pages 3125-3133
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSMinimum thermal and cold neutron source strength necessary for the thermonuclear ignition of D–T fuel using the energy released in exothermic 3He(n, p)T reaction is determined for representative tokamak parameters, when the tokamak inner walls are lined with good thermal neutron reflectors. It is found, that D–T ignition is possible with the help of currently available neutron sources if the particle and energy confinement times exceed tens of seconds. If thermal or cold neutron sources having strength greater than 1023 s−1 can be constructed, then D–T ignition is possible even in plasmas having energy and particle confinement times in the range of one tenth of a second. Although the focus here is on tokamak fusion reactors the results are applicable to other type of reactors as well.View full abstractDownload PDF (1106K) -
Yoshio Tsuji1992 Volume 61 Issue 9 Pages 3134-3138
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSPhysical significance of nτ is studied, where n is the number density and τ the confinement time of a reaction. By introducing a fundamental parameter, the ideal and the actual ignited combuson criteria for various reactions are compared. The reason why the hurdle of nτ is very high for nuclear fusion by magnetic confined plasma, while very low for chemical reaction and nuclear fission by thermal neutron, is clarified.View full abstractDownload PDF (584K) -
Mamoru Tanibayashi1992 Volume 61 Issue 9 Pages 3139-3145
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSDiffraction of light by quasi-periodic gratings constructed as Fibonacci series or three other similar series are reported. The observed diffraction patterns show rich structures which are self-similar, and the diffraction angles are related to irrational numbers.View full abstractDownload PDF (798K) -
Rama Shankar, T. V. Singh1992 Volume 61 Issue 9 Pages 3146-3152
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSIn this paper, modified Rusanov’s third order difference scheme for quasilinear hyperbolic system of partial differential equation in non-conservative form has been presented. The method is then applied to study the unsteady motion of converging cylindrical shock waves in radiation gas dynamics. It is concluded that a cylindrical shock wave in a radiating gas increases in strength as it is propagating towards the axis. It is also observed that the effect of radiation heat transfer is to decrease the growth rate of shock strength when it is propagating towards the axis. Further, it is concluded that the effect of radiation heat transfer is to delay the shock convergence with axis and thus increase the convergence time. In the process the detailed behaviour near the axis at the time of shock coalescence is studied. The effects of various controlling parameters on the numerical results are also studied.View full abstractDownload PDF (684K) -
Kazuaki Kurihara, Yasuhito Kiwamoto, Teruo Saito, Kiyoshi Yatsu, Syoic ...1992 Volume 61 Issue 9 Pages 3153-3165
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA theoretical model is developed on the electrostatic potential which is formed during fundamental electron cyclotron resonance heating in an end region of a tandem mirror. The model includes experimental conditions such as expanding magnetic flux tube, multicomponent electron temperature and secondary electrons emitted from an end plate. The axial potential profile of a collisionless plasma is analyzed with non-Maxwellian velocity distribution functions of ions and electrons. The potential profile in the plasma region, where the charge-neutrality holds, depends predominantly on the magnetic field profile. The potential drop in the sheath region in front of the end plate strongly depends on the secondary electrons and the fraction of the higher temperature component of the primary electrons.View full abstractDownload PDF (1582K) -
Hideo Sugama, Masahiro Wakatani1992 Volume 61 Issue 9 Pages 3166-3177
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA new anomalous transport model for resisistive interchange turbulence is derived from statistical analysis applying two-scale direct-interaction approximation to resistive magnetohydrodynamic equations with a gravity term. Our model is similar to the K-ε model for eddy viscosity of turbulent shear flows in that anomalous transport coefficients are expressed in terms of by the turbulent kinetic energy K and its dissipation rate ε while K and ε are determined by transport equations. This anomalous transport model can describe some nonlocal effects such as those from boundary conditions which cannot be treated by conventional models based on the transport coefficients represented by locally determined plasma parameters.View full abstractDownload PDF (1219K) -
Naoki Yamamoto, Makoto Kikuchi, Tooru Atake, Akihiro Hamano, Yasutoshi ...1992 Volume 61 Issue 9 Pages 3178-3188
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSBaZnGeO4 undergoes several successive phase transitions from I to V phase. The modulated structure in the incommensurate phases (III and IV) and the commensurate-incommensurate phase transition between the IV and V phases were studied by electron microscopy. The direction of the modulation wave vector slightly deviates from the c* direction, and the tilt angle changes with temperature. The modulated structure does not change into the discommensuration (DC) arrays around the III′ phase, but the DC’s appear in the IV phase near the C–IC phase transition temperature. The electron microscope images clearly revealed that the stripples and antistripples composed of the three DC’s were formed and moved in the DC lattice during the C–IC phase transition.View full abstractDownload PDF (3812K) -
Kêichiro Aizu1992 Volume 61 Issue 9 Pages 3189-3195
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSIt is assumed that the order parameters are two pairs {Qα, Qα*} and {Qβ, Qβ*}. Qα is set equal to qα exp iψα, and Qβ to qβ exp iψβ. The ordinary or standard form of a gradient-linear term in the free energy function is Qα*∂xQα−Qα∂xQα*+Qβ*∂yQβ−Qβ∂yQβ*, which contains only ∂ψ’s and not ∂q’s (as is well known). The present paper proposes a new form, which, in contrast to the standard form, contains only ∂q’s and not ∂ψ’s. This new form is specified as |Qβ|2∂z|Qα|2−|Qα|2∂z|Qβ|2, appropriate to be called the absolute form. The P\bar4b2-(1/2, 0, 0) case is investigated. In this case, several commensurate phases, two incommensurate phases of the standard gradient form and two incommensurate phases of the absolute gradient form are deduced from the free energy function. Centering around the last phases, basic considerations are performed.View full abstractDownload PDF (763K) -
Takashi Nagatani1992 Volume 61 Issue 9 Pages 3196-3202
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA competing two-species growth model, which is a generalized directed percolation, is presented to study the fractal structure of a self-affine pattern at the phase transition point. The growth model is described in terms of a stochastic cellular automaton. The morphology and the phase transition are investigated by using computer simulation. The phase diagram and the composition ratio in the steady state are found. The fractal structures of self-affine patterns along the phase transition line are investigated. Its fractal dimension df=1.48±0.02 is found on the transition line. Also, near a singular point, the crossover from the Sierpinski gasket to the homogeneous mixture is found. A mean-field theory is presented.View full abstractDownload PDF (863K) -
Masanori Inui, Shin’ichi Takeda, Tetsuo Uechi1992 Volume 61 Issue 9 Pages 3203-3208
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe measurement of ultrasonic velocity and sound attenuation, and density has been carried out for several liquid Bi–Ga alloys from the melting points to about 800°C. The ultrasonic velocity and its attenuation were determined by means of an ultrasonic pulse transmission method and the density was determined by a γ-ray absorption method. The adiabatic compressibility and molar volume of this system are obtained by the observed sound velocity and density. The temperature coefficient of the adiabatic compressibility is rather small in the concentration above the miscibility gap region than in the other concentration. The thermodynamic properties of this system are discussed based on the correlation between the structure and the compressibility.View full abstractDownload PDF (591K) -
Shoji Yamamoto, Hideo Fukutome1992 Volume 61 Issue 9 Pages 3209-3219
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe electronic structure of the strongly correlated one dimensional Hubbard model is calculated by the resonating Hartree-Fock (Res HF) method. In the strong correlation regime with the Coulomb repulsion U\gtrsim6, SDW solitons localize almost on the central two sites and only one kind of neutral soliton pair has a much smaller energy than the other pairs. As quantum fluctuations in a periodic chain with 12 sites, we consider up to three diradical breathers consisting of the low energy neutral soliton pair. The Res HF ground state can explain 77.8% (U=6) and 80.1% (U=8) of the exact correlation energy. This is much better than the Gutzwiller method to use the SDW as the reference state that explains about 50% of the correlation energy. The breather fluctuations explain the rapid decreases in the short distance of the spin and staggered spin correlation functions. Other correlation functions and the excited states due to the quantum fluctuations are studied.View full abstractDownload PDF (1309K) -
Arisato Kawabata1992 Volume 61 Issue 9 Pages 3220-3229
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA theory of electron scattering by potential with slow spatial variation in one-dimensional systems is proposed. It takes into account the perturbation of all order taking advantage of the long range nature of the potential. The theory is extended to the case of random potential and good agreements with the numerical calculation are obtained for wide range of parameters, while the precision of Born approximation becomes rapidly worse if the correlation length of the potential exceeds the wave length of the electron. As an application, the mobility of quantum wires limited by the surface roughness scattering is discussed.View full abstractDownload PDF (984K) -
Morio Suzuki, Kazunori Komorita, Hiroshi Nakano, Leo Rinderer1992 Volume 61 Issue 9 Pages 3230-3238
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe tunneling spectroscopy was performed for the Ag or Pb–SiO–Ba Pb0.75Bi0.25O3 (referred to BPBO) planer junction. For the junction with the Ag electrode, the superconducting-gap (2Δ) is equal to 3.2 meV and 2Δ0⁄kBTc to 3.6. It was found that when a value of Δ is determined so that the temperature dependence of Δ agrees with the one of BCS theory, the temperature dependence of a recombination time of a quasiparticle largely deviates from the one of BCS theory. The deviation is explained by a fact that the V−dI⁄dV characteristic contains a component of a leak-current beside a tunnel one. While, for the junction with the Pb electrode, it was found that 2Δ at 4.2 K is equal to 9 meV. This large value comes from a zero-bias anomaly. The increase of a slope toward zero-bias in the V−dI⁄dV characteristic suggests that the energy band near the Fermi energy in BPBO is strongly nonparabolic and has a gap caused by the charge density wave.View full abstractDownload PDF (1211K) -
Koji Satori, Hiroyuki Shiba, Osamu Sakai, Yukihiro Shimizu1992 Volume 61 Issue 9 Pages 3239-3254
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA magnetic impurity doped in a superconductor produces a localized excited state within the energy gap. This problem is studied by applying Wilson’s numerical renormalization group method. The ground state and the first excited state are traced by changing the exchange coupling constant relative to the energy gap. Thereby the position of the localized excited state within the energy gap is determined over the whole regime of the magnitude of TK⁄Δ (TK: Kondo temperature, Δ: superconducting energy gap). A crossing of the lowest doublet and singlet is clearly observed at TK⁄Δ\simeq0.3. The ferromagnetic and Ising cases have been studied also. In the ferromagnetic case the localized excited state stays close to the gap edge since the exchange coupling is renormalized to a weak coupling. The case of the Ising-like sd coupling, which is exactly solvable, can be used to check the reliability of the present approach and the effect of the discretization.View full abstractDownload PDF (1481K) -
Tetsuya Takeuchi, Mitsuru Ono, Hidenobu Hori, Taturu Yosida, Akio Yama ...1992 Volume 61 Issue 9 Pages 3255-3261
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSMagnetization measurements have been performed on the single crystal samples of Ni(C2H8N2)2NO2(ClO4), NENP, and Ni(C3H10N2)2NO2(ClO4), NINO in pulsed high magnetic fields. No magnetization appears up to about 10 T reflecting the presence of the Haldane gap and the linear magnetization appears in both compounds above this field. The observed anisotropy of the transition field is explained by the Haldane gap energy Eg and the crystalline field constants D and E in the lowest excited triplet. The parameters are estimated as Eg=16.8 K, D=−16.1 K, and E=−1.3 K and Eg=14.2 K, D=−11.5 K and E=2.1 K for NENP and NINO, respectively.View full abstractDownload PDF (666K) -
Tetsuya Takeuchi, Hidenobu Hori, Taturu Yosida, Akio Yamagishi, Koichi ...1992 Volume 61 Issue 9 Pages 3262-3266
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSMagnetization measurements have been performed on the Haldane gap materials (CH3)4NNi(NO2)3 (TMNIN) and Ni(C3H10N2)2N3(ClO4) (NINAZ) in pulsed high magnetic fields. TMNIN shows a typical magnetization profile of the Haldane material with the gap energy of 4.1 K. Quenching of the gap appears around 2.7 Tesla(T) and magnetic saturation is obtained above 30 T. In NINAZ, however, the quenching appears at around 30 T reflecting a large Haldane gap energy with the magnitude of 44.3 K.View full abstractDownload PDF (583K) -
Kazuhiko Satoh, Akira Fukada, Izuru Umehara, Yoshichika \={O}nuki, Hid ...1992 Volume 61 Issue 9 Pages 3267-3276
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSWe have measured the electrical resistivity, Hall coefficient, thermoelectric power, magnetoresistance, magnetic susceptibility and magnetization of the antiferromagnetic Kondo-lattice compound CeCu2 using a high-quality single crystal. Anisotropy reflected in the above quantities is explained by the orthorhombic crystalline electric field. We discuss the metamagnetic behavior and the negative magnetoresistance which scales with a square of the magnetization.View full abstractDownload PDF (1176K) -
Tsutomu Momoi, Masuo Suzuki1992 Volume 61 Issue 9 Pages 3277-3286
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe chiral order in the spin 1/2 XXZ antiferromagnet H=J∑(σixσjx+σiyσjy+Δσizσjz) and especially in the XY antiferromagnet on a two-dimensional triangular lattice is studied using the super-effective-field theory. In the XY model the size dependence of the critical temperatures indicates the existence of the long-range chiral-order at sufficiently low temperatures in the infinite system. Phase diagram of the chiral order in the XXZ antiferromagnet is studied.View full abstractDownload PDF (1200K) -
Tatsuichi Hamasaki, Hidenori Kubo1992 Volume 61 Issue 9 Pages 3287-3291
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSIn order to clarify the spin structure of mixed antiferromagnets Co1−xNixCl2·6H2O, proton NMR spectra are observed in an applied magnetic field along the b axis perpendicular to each easy axis. The resonance fields shift gradually from their positions in CoCl2·6H2O to those in NiCl2·6H2O upon increasing Ni concentration, x. From analyzing the Ni concentration dependence of these resonance fields, it is shown that the spin directions of these mixtures vary smoothly from the c axis (the easy axis of CoCl2·6H2O) to the a″ axis (the easy axis of NiCl2·6H2O) that is in a good agreement with the model proposed by Matsubara et al. It is confirmed that the oblique antiferromagnetic phase does not occur.View full abstractDownload PDF (584K) -
Hidekazu Tanaka, Tetsuya Kato, Katsunori Iio, Kazukiyo Nagata1992 Volume 61 Issue 9 Pages 3292-3302
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe magnetic properties of RbVBr3 with a deformed CsNiCl3 structure were investigated by means of the susceptibility and torque measurements. RbVBr3 undergoes the successive transitions, TN1=28.0 K and TN2=21.3 K and 19.0 K on heating and cooling, respectively. A large hysteresis was observed for the transition at TN2. Metastable states appear between the intermediate phase and low-temperature phase. The intermediate phase has the weak ferromagnetic moment of the order of 10−5 μB perpendicular to the c-axis, while the low-temperature phase does not. It is compatible with the crystal structure that the weak moment due to the Dzyaloshinsky-Moriya interaction appears in linear chains. It is concluded that in the intermediate phase the spins form a collinear structure, probably ferrimagnetic one in the c-plane and a triangular one in the low-temperature phase.View full abstractDownload PDF (1359K) -
Taichi Terashima, Norimichi Kojima1992 Volume 61 Issue 9 Pages 3303-3312
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe magnetic susceptibilities and magnetizations of incommensurate layer compounds (CeS)1.2NbS2 and (CeS)0.6NbS2 are reported. The magnetic susceptibilities in the paramagnetic region of the above two compounds are analyzed taking account of the crystal field acting on Ce3+ and the molecular field. The crystal field splitting of 2F5⁄2 multiplet (Ce3+) is estimated at ca. 500 K. The large splitting suggests that the screening of the crystal field by conduction electrons is weak in the CeS layer. The compound (CeS)1.2NbS2 orders antiferromagnetically near 3 K accompanied by a weak-ferromagnetic moment, while a magnetic ordering with a spontaneous magnetization is observed near 3 K in (CeS)0.6NbS2. Both the two compounds display a metamagnetic transition at 2.3 kOe (T=2.0 K). Possible magnetic structures are discussed in terms of ferromagnetic CeS layers.View full abstractDownload PDF (1298K) -
Masahito Yoshizawa, Hirotaka Seki, Kôki Ikeda, Kaoru Okuno, Mits ...1992 Volume 61 Issue 9 Pages 3313-3321
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSMagnetization and electrical resistivity of chemically analyzed Ni3Al alloys have been measured. The sample Ni75.07Al24.93 shows a ferromagnetic transition at 43.7 K. This result confirms the ferromagnetism of stoichiometric Ni3Al. The magnetic field effect on the electrical resistivity has been investigated from a viewpoint of quenching of spin fluctuation. The suppression of the coefficient A of the squared temperature in the resistivity has been observed for both weakly ferromagnetic and strongly paramagnetic samples. Characteristic magnetic field H0 for the quenching of spin fluctuation was estimated from the resistivity data. The value of H0 shows a minimum near the boundary between paramagnetic and ferromagnetic compositions.View full abstractDownload PDF (951K) -
Yoshikazu Suzumura, Hidetoshi Fukuyama1992 Volume 61 Issue 9 Pages 3322-3330
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe insulating state of (R1, R2-DCNQI)2Cu salts showing both the mixed valence of Cu+ and Cu++ and the three-fold lattice distortion has been examined by the mean-field theory to the periodic Anderson model where two one-dimensional conduction bands with the electron-phonon interaction are coupled to Cu ions. For the choice of the interaction constant which leads to approximately Cu+4⁄3 as an average, it is shown that modulations of both charge density and spin density coexist in the ground state and that the phase transition at finite temperature is of the first order.View full abstractDownload PDF (927K) -
Nobuo Furukawa, Masatoshi Imada1992 Volume 61 Issue 9 Pages 3331-3354
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe Hubbard model on a square lattice in the ground state is investigated. Various aspects of Mott transition at half-filling are clarified from the quantum Monte Carlo study. Critical exponents of the transition for charge and spin correlations are estimated. For the doping concentration δ, the charge susceptibility is proportional to δ−1 indicating the divergence of charge mass for δ→0, while the spin susceptibility is always finite and not singular near δ=0. Several theoretical consequences of the above results are discussed. Incommensurate peak amplitude of spin correlation scales as (δ−δc)−1 with δc<0.01 in disagreement with RPA results ln(δ−δc). The antiferromagnetic order at the half-filling also shows strong correlation character and is not sensitive to the shape of the fermi surface, while the incommensurate peak observed away from the half-filling is sensitively suppressed by the loss of partial nesting consistently with the weak coupling picture. Comparisons with experimental indications of high-Tc oxides are made.View full abstractDownload PDF (3046K) -
Kenji Nakajima, Kazuhisa Kakurai, Haruhiro Hiraka, Hidekazu Tanaka, Ka ...1992 Volume 61 Issue 9 Pages 3355-3360
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSQuasielastic and inelastic neutron scattering experiments on S=1 quasi 1-D Heisenberg antiferromagnet, RbNiCl3 were performed. The temperature dependence of the spin correlation length suggests a finite 1-D correlation even at T=0 (K). The dispersion relation in the 3-D ordered phase can be well described by the phenomenological theory of a quasi 1-D Heisenberg antiferromagnet including the Haldane effect. Our results support early works on CsNiCl3 suggesting the influence of the novel quantum effect even in 3-D ordered phase of the quasi 1-D, S=1 Heisenberg antiferromagnet.View full abstractDownload PDF (770K) -
Masayuki Kawakami, Jiro Watarizaki1992 Volume 61 Issue 9 Pages 3361-3369
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSNMR measurements have been made for Y2Co14B and Gd2Co14B by the steady-state and spin-echo methods in zero external field as a function of temperature. By the steady-state method, the 59Co domain signals with quadrupole splittings which originate from six non-equivalent Co sites have been observed together with wall signals for the two compounds. It is found that the spin echo peaks generally correspond to wall signals but not to domain signals in these compounds. The hyperfine field at Co nuclei in domains and the spacing between the quadrupole-split component lines for the domain signals are derived. The effect of substitution of Gd for Y on the Co hyperfine field and the magnetic exchange interaction between Co magnetic moments in the compounds is discussed.View full abstractDownload PDF (1111K) -
Hitoshi Ohta, Nobuyasu Yamauchi, Mitsuhiro Motokawa, Masaki Azuma, Mik ...1992 Volume 61 Issue 9 Pages 3370-3376
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSESR experiments on powder samples of SrCuO2 and Sr2CuO3 have been tried in the submillimeter wave region. No resonance absorption has been observed on freshly prepared samples at the temperatures from 86 K to 265 K, while the samples left in the air for a few months have revealed distinct magnetic resonance signals around g=2. Especially the complicated line shape of Sr2CuO3 suggests the overlap of two kinds of EPR, one of which is related to the EPR observed in SrCuO2. From the results of H2O gas exposed samples, the effect of H2O to these samples is discussed.View full abstractDownload PDF (785K) -
Yoshihiro Ishibashi1992 Volume 61 Issue 9 Pages 3377-3384
Published: September 15, 1992
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSDomain walls between the incommensurate and commensurate regions are considered on the basis of a thermodynamic potential. It has turned out that there is a unique wall structure which minimizes the wall energy. By utilizing the results obtained, a mechanism of the transient processes between the incommensurate and the commensurate states is discussed, criticizing a previously proposed transient mechanism based upon a “particular” thermodynamic potential.View full abstractDownload PDF (864K) -
Eisuke Iguchi, Keisuke Akashi1992 Volume 61 Issue 9 Pages 3385-3393
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSDielectric properties and dc-conductivities in p-type NiO doped with Li (1∼10 atomic%) were investigated below 300 K. Around 40 K, a dielectric relaxation peak appeared with an activation energy of 0.051 eV and the intensity of this peak was found to be thermally activated, the activation energy being 0.01 eV. There was a linear relation between log (σT3⁄2) and 1⁄T in the range of ∼45 to ∼90 K and the activation energy was 0.057 eV. These behaviours have been discussed in terms of hopping process of nonadiabatic small polarons. The theoretical estimates of electron-phonon-coupling constants, λ, and the changes in spacings between ions, x, associated with formation of a polaron have been carried out. The calculations yield λ and x between Ni3+ and Ni2+ in ⟨110⟩ directions are −3.48 eV/Å and −9.6×10−3 Å and these between Ni3+ and O2− in ⟨100⟩ directions are 0.42 eV/Å and 5.12×10−2 Å. This theoretical calculation provides an evidence on stability of nonadiabatic small polarons in p-type NiO.View full abstractDownload PDF (1222K) -
Kazuo Gesi1992 Volume 61 Issue 9 Pages 3394-3399
Published: September 15, 1992
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSDielectric properties of deuterated dicalcium double propionates, Ca2Pb-(C2D5COO)6 (DDLP) and Ca2Pb(C2D5COO)6 (DDBP), have been studied. The I–II (the Curie temperature) and II–III transition temperatures of annealed DDLP crystal are 313.1 K and 172 K, respectively. They are 14∼20 K depressed by deuteration. The isotope effect on DLP is much conspicuous in comparison with that of Ca2Sr(C2H5COO)6 (DSP). The temperature dependence of spontaneous polarization in DDLP is measured and compared with that of Ca2Pb(C2H5COO)6 (DLP). The I–II and II–III transition temperatures of DDBP are 275 K and 204.5 K, respectively. The deuteration causes an increase of about 8 K in the I–II transition temperature, but does not change virtually the II–III one.View full abstractDownload PDF (626K)