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Shozo Takeno, Kenji Kisoda
1988 Volume 57 Issue 3 Pages
675-678
Published: March 15, 1988
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Kinks connecting nondegenerate minima of an on-site potential of a one-dimensional nonlinear lattice with dissipation are studied. Such kinks are self-sustained ones in the sense that being a kink or an antikink and the kink velocity are uniquely related to a friction coefficient which is either positive or negative. Nonlinear lattice equations are solved numerically for a model on-site potential with anharmonicity up to the sixth order by using as an input a discrete version of exact one-kink solutions which exist in their continuum limit. The main result so obtained is: (1) a smooth propagation of a single kink with width down to about one-third of the lattice constant and (2) various features of two-kink states generated by kink-antikink head-on collisions which are different for different forms of the on-site potential and different colliding kink speeds.
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Yoko Hase, Junkichi Satsuma
1988 Volume 57 Issue 3 Pages
679-682
Published: March 15, 1988
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A system comprised of the nonlinear Schrödinger equation coupled to the Boussinesq equation is proposed. This system reduces to the nonlinear Schrödinger equation, the Zakharov equations, or the equations studied by Nishikawa
et al., (as well as Yajima and Satsuma), for an appropriate choice of parameters. It is found that an N-soliton solution exists for a particular choice of parameters.
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Masuo Suzuki
1988 Volume 57 Issue 3 Pages
683-686
Published: March 15, 1988
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A new scheme to study phase transitions is formulated and a general criterion of order parameters is proposed on the basis of the newly formulated super-effective-field theory. This is applied to spin glasses and chiral (or helical) orders.
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Junji Suzuki
1988 Volume 57 Issue 3 Pages
687-690
Published: March 15, 1988
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The connectivity constant of Hamiltonian paths on 2-D lattices with a coordination number=3 are evaluated. The results agree well with the mean field value obtained by Orland
et at.
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Yoshimi Tsuchiya, Masatoshi Kudoo, Chun-Yuan Yang
1988 Volume 57 Issue 3 Pages
691-694
Published: March 15, 1988
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In a thin layer of a nematic liquid crystal confined within a small aspect ratio cell, window-like coherent states and their subharmonic bifurcations have been found to occur in a successive transition process of the Williams domain. By an increase of the voltage applied across the thin layer of the liquid crystal, the Williams domain becomes unstable and two types of coherent pattern oscillations OS1 and OS2 appear successively. In the region of OS1, the pattern oscillation repeats the window-like coherent states and their subharmonic bifurcations. The oscillation OS2 shows another pattern behavior different from the OS1.
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Jun Yokokawa, Osamu Konno, Izumi Nomura, Toshimi Suda, Toshiji Suzuki, ...
1988 Volume 57 Issue 3 Pages
695-698
Published: March 15, 1988
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The cross sections for
12C(γ,
p) were measured with tagged polarized photons in the energy range from 41.2 to 93.0 MeV. The photon energy and angular dependence of the analyzing power have been extracted. The results are in better agreement with predictions of the one-nucleon knockout model and RPA theory, than that of the quasi-deuteron model, particularly at higher photon energies.
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Akira Onuki
1988 Volume 57 Issue 3 Pages
699-702
Published: March 15, 1988
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A model is presented to describe strongly deformed gels near the volume phase transition. Gels undergo a very unique phase transition if they are affinely deformed. Lamellar or cylindrical domains are predicted to emerge in the phase separation processes. The scattered light intensity is calculated for uniaxially deformed gets.
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Akira Onuki
1988 Volume 57 Issue 3 Pages
703-706
Published: March 15, 1988
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A stable pattern is calculated for uniaxially stretched gels. The gel surface is shown to fold periodically, yielding cusps on the surface.
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Shunjiro Shinohara, Osamu Naito, Kenro Miyamoto
1988 Volume 57 Issue 3 Pages
707-710
Published: March 15, 1988
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The excitation of the second harmonics and its wave damping near the subharmonic cyclotron resonance layer of ω=2.5ω
D have been proposed for the ion Bernstein wave in tokamaks (ω
D: deuteron cyclotron frequency). By the use of three-dimensional ray tracing and a coupling theory, it is found that the second harmonic wave can be excited as a real wave through a nonlinear process (resonant mode-mode coupling). This excited wave can propagate toward the high-field side, and lose its energy through harmonic cyclotron damping and/or electron Landau damping.
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Hitoshi Hojo, Mitsuhiro Shigeta, Tsuguhiro Watanabe
1988 Volume 57 Issue 3 Pages
711-714
Published: March 15, 1988
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Flute mode instability driven by a nonuniform radial electric field is investigated in the local theory. From the analysis of the local dispersion equation derived from the profiles of Gaussian density and parabolic ambipolar potential, it is shown that a flute mode is reactively destabilized in the case of a well-type potential and that this mode can be stabilized by the Landau damping caused from the velocity shear of the
E×
B drift for a stronger electric field. The flute mode propagates in the direction of the ion diamagnetic drift in the
E×
B drifting frame of the electron. The threshold for the instability is obtained analytically, which is in good agreement with that obtained numerically. The physical mechanism of the instability is explained. The effect of the velocity shear of the
E×
B drift on flute interchange modes is also discussed.
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Koich Kindo, Kimikazu Hazumi, Muneyuki Date
1988 Volume 57 Issue 3 Pages
715-717
Published: March 15, 1988
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The fractal dimension of field-induced martensitic transformation in iron-based alloys is investigated. The martensitic phase (bcc) appears in the parent austenitic phase (fcc) when a strong magnetic field is applied under suitable temperatures. It is found that microstructural patterns of the grown martensitic domains on a metal surface show a clear fractal nature with a fractal dimension of 1.81±0.02. This result means that the fractal dimension of the martensitic transformation is larger than that of diffusion-limited crystal growth where the dimension is 1.6∼1.7. The result may qualitatively explain that the growing point of the crystal in the diffusion-limited case has a characteristic of a one-dimensional extention, while the martensitic transformation is diffusionless and mainly ruled by two- or three-dimensional stress.
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Yukikuni Akishige, Tooru Atake, Yasutoshi Saito, Etsuro Sawaguchi
1988 Volume 57 Issue 3 Pages
718-721
Published: March 15, 1988
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The specific heat
Cp of hexagonal barium titanate has been measured over a wide temperature range from 50 K to 300 K. The
Cp curve shows a typical second-order-type anomaly at
T0=222.7 K; the transition enthalpy
ΔH, transition entropy
ΔS and specific heat jump
ΔCp at
T0 are estimated to be 2.2×10
2 J/mol, 1.2 J/mol·K and 4.2 J/mol·K, respectively. The data satisfy the Ehrenfest relation. The
Cp anomaly associated with the ferroelectric phase transition at about 74 K has not been detected. A discussion concerning the critical indices on the phase transition at 222.7 K is presented.
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Kazumasa Miyake, Tamifusa Matsuura, Kazuhiro Sano, Yosuke Nagaoka
1988 Volume 57 Issue 3 Pages
722-725
Published: March 15, 1988
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It is proposed that the physics of high-
Tc superconductors with a CuO
2 network can be understood in a way parallel to that of heavy-fermion superconductors where the spin fluctuations play an important role. On the basis of a periodic Wolff model with aspects specific to copper oxides, it is shown that the charge carriers are the
p-like holes when the antibonding band is filled less than half. It is also shown that these charge carriers form relatively heavy Fermi liquid with an effective bandwidth
T0∼10
3 K, which is consistent with experiments.
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Masaru Kato, Yoshikazu Suzumura, Yutaka Okabe, Kazushige Machida
1988 Volume 57 Issue 3 Pages
726-729
Published: March 15, 1988
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It is shown theoretically that antiferromagnetic fluctuations enhance the superconducting transition temperature drastically for the anisotropic pairing state,
e.g. the d-wave-like pairing, because of the pseudo-gap formation due to the fluctuations.Within the renormalized random phase approximation (RRPA), an imperfect nesting model for a two-dimensional square lattice is investigated. Implication of the results is discussed in connection with the high-
TC oxide superconductors.
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Kokichi Oshima, Hatsumi Urayama, Hideki Yamochi, Gunzi Saito
1988 Volume 57 Issue 3 Pages
730-733
Published: March 15, 1988
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An upper critical field measurement in the recently discovered ambient pressure organic superconductor (BEDT–TTF)
2Cu(NCS)
2 (
Tc=10.4 K) is reported. Three- to two-dimensional crossover behaviour is observed in the temperature dependence of the parallel critical field. The anisotropy of the coherence length near
Tc, ξ
c⁄ξ
a*, is about 19 and ξ
a*(0) is smaller than the lattice spacing along the
a*-axis. An unusual temperature dependence of the perpendicular critical field is observed far below
Tc. It is confirmed that deuterated salt is also an ambient pressure superconductor with a slightly higher
Tc (11 K).
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Yoshio Kitaoka, Kenji Ishida, Shigeru Hiramatsu, Kunisuke Asayama
1988 Volume 57 Issue 3 Pages
734-736
Published: March 15, 1988
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The magnetic phase diagram of (La
1−xBa
x)
2CuO
4 has been studied using the
139La nuclear quadrupole resonance (NQR) technique. The ordering temperature
TN has been determined from the temperature dependence of the internal magnetic field at the La site proportional to the Cu magnetic moment. It has been found that
TN markedly decreases from
TN∼240 K for
x=0, to 12 K for
x=0.008, however the magnitude of the Cu magnetic moment at 1.3 K is almost constant. On the other hand, in the composition range of 0.008<
x<0.025,
TN gradually decreases down to ∼1.5 K for
x=0.025 where the superconductivity appears. This demonstrates that two-dimensional correlations within the CuO
2 in-plane are quite strong. The magnetic phase diagram established from a microscopical point of view suggests a strong relationship between the antiferromagnetism and the superconductivity.
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Yoshio Kitaoka, Shigeru Hiramatsu, Kenji Ishida, Kunisuke Asayama, Hid ...
1988 Volume 57 Issue 3 Pages
737-740
Published: March 15, 1988
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Masayuki Hagiwara, Toshimasa Uemura, Yoshiaki Chiba, Muneyuki Date
1988 Volume 57 Issue 3 Pages
741-743
Published: March 15, 1988
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Temperature dependence of N
1-center, a deep donor nitrogen in diamond, is investigated. A clear change in the hyperfine structure of the center is observed around 680 K. The result, explained by the model, is that the self-trapped state with uniaxial symmetry which is stable at low temperatures changes to an isotropic donor state above 680 K.
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Yoh Kohori, Hirofumi Shibai, Yasukage Oda, Takao Kohara, Yoshio Kitaok ...
1988 Volume 57 Issue 3 Pages
744-746
Published: March 15, 1988
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An NQR study of Cu in SmBa
2Cu
3O
7−y has been performed. Two pairs of signals were observed around 20–23 and 30–33 MHz. The nuclear spin lattice relaxation rate,
T1−1 at the higher frequency site shows a weak temperature dependence in the normal state, while it decreases rapidly without enhancement just below
Tc. The values of
T1−1 above 80 K are almost the same as that in Y-based compounds. At low temperatures,
T1−1 is governed by Sm spin fluctuations. From the analysis of this contribution, we conclude that the signals apearing around 30 and 22 MHz in Sm- and Y-based compounds are attributed to Cu in the Cu–O plane and Cu–O chain, respectively.
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Keiichi Kaneto, Fumito Uesugi, Katsumi Yoshino
1988 Volume 57 Issue 3 Pages
747-749
Published: March 15, 1988
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In stretched polythiophene films, absorptions due to photo- and doping-induced (bi)polarons are found to be highly anisotropic, similar to a π−π
* transition. It is also found that the generation efficiency of polarons does not depend on the polarization of excitation lights. This result is discussed in terms of an initial mechanism of photoinduced polarons.
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S. Baboolal
1988 Volume 57 Issue 3 Pages
750-751
Published: March 15, 1988
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Since the satellite observations of auroral double layers by Temerin and others, several small amplitude theories have been proposed to account for these. In a recent such theory [J. Phys. Soc. Jpn.
56 (1987) 139] for typical rarefactive double layers supposedly better agreement is obtained by employing negative ion plasma models. However, by means of a recent numerical theory by the author and others, we have been unable to obtain double layers in such plasma. We therefore re-examine the above small amplitude theory and the observed parameter values of Temerin in order to explain the discrepancy.
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R. A. Leo, G. Mancarella, G. Soliani
1988 Volume 57 Issue 3 Pages
753-756
Published: March 15, 1988
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We point out some aspects of the Estabrook-Wahlquist prolongation method in the search for Bäcklund transformations of the Broer-Kaup hydrodynamical equation.
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Tetsuo Deguchi, Yasuhiro Akutsu, Miki Wadati
1988 Volume 57 Issue 3 Pages
757-776
Published: March 15, 1988
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New link polynomials, reported in I and II of the series, are extended into those with two variables. A concept of composite string is introduced. It is shown that the composite string representation and the generalized Ocneanu’s trace lead to a sequence of two-variable link polynomials. In addition, algebraic aspects of the composite string representation are studied in some detail.
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Hidetoshi Konno
1988 Volume 57 Issue 3 Pages
777-790
Published: March 15, 1988
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A two-dimensional (2D) non-linear Brownian oscillator in the potential;
V(
x,
y)=
A1(
x+
y)+
A2(
x2+
y2)⁄2+
A4(
x4+
y4)⁄4+
Cx2y2⁄2, is numerically studied from the statistical mechanical viewpoint. We found that: (i) under large dissipation, the probability density function of the oscillator takes a form
Ws(
x,
y)∝ exp (−
V(
x,
y)⁄
T*) although the coupling term
Cx2y2 exists; (ii) the occurrence of jump events in a strongly dissipative case (
A2<0 and
A4>0) has a quasi-Poisson character even when the Kramer’s theory of activation process is unavailable; (iii) as far as the Smoluchowski’s approximation is valid, a generalized fluctuation-dissipation theorem (FDT) for the 2D non-linear Brownian oscillator can be constructed as a natural extension of Okabe’s theory for Kubo’s problem. System identification with use of the generalized FDT is also discussed.
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Xiao Hu, Masuo Suzuki
1988 Volume 57 Issue 3 Pages
791-806
Published: March 15, 1988
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The systematic Weiss-like and Bethe-like approximations based on the mean-field transfer-matrix method are used to investigate the asymptotic behavior of the induced magnetization on a semi-infinite square lattice, and to investigate the wave-number dependence of the susceptibility in a nonuniform external field. The critical exponents ν, ν′, η
i and η are estimated following the general CAM prescription. A new scaling relation ν·η
i=β is obtained in the framework of the finite-degree-of-approximation scaling. Together with previous papers, all the static critical exponents have been estimated by the CAM, and are shown to satisfy the well-known scaling relations.
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Makoto Katori, Masuo Suzuki
1988 Volume 57 Issue 3 Pages
807-817
Published: March 15, 1988
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The coherent-anomaly method (CAM) is applied to the kinetic Ising model. Dynamical cluster-mean-field approximations are formulated to obtain a series of the dynamical mean-field critical coefficients. The coherent-anomaly scaling relations are derived on the basis of the scaling form of the generating function in nonequilibrium systems to estimate the exponent
Δ of the critical slowing down. The dynamical critical exponent is estimated as
Δ\simeq2.15(±0.02) for the kinetic Ising model on the two-dimensional triangular lattice.
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Junji Suzuki, Takeo Izuyama
1988 Volume 57 Issue 3 Pages
818-827
Published: March 15, 1988
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The Flory-Huggins model without solvent molecules on a brick lattice is solved exactly by the Bethe ansatz. It is shown that polymer melting given by this model is a second order transition which verifies the conjecture of Gujrati and Goldstein. It is also found that the gauche fraction turns out to be zero in the low-temperature phase.
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Saburo Homma, Mitsutaka Kanazawa, Koichi Maruyama, Yojiro Murata, Hide ...
1988 Volume 57 Issue 3 Pages
828-843
Published: March 15, 1988
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Differential cross sections of the reaction γp→ηp have been measured by using a tagged photon beam in the energy range from 808 MeV to 1008 MeV at θ
η*=45°, 80°, 100° and 110°. Photon couplings of nucleon resonances with masses below 1700 MeV are determined by a partial wave analysis of the reaction γp→ηp based on the isobar model. Results are compared with photon-couplings obtained by the analysis of the reaction γN→πN and by the quark model calculation.
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Toshiyuki Nishitani
1988 Volume 57 Issue 3 Pages
844-855
Published: March 15, 1988
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This paper treats the similarity transformation of the Navier-Stokes equations for a two-dimensional compressible viscous flow. The transformation of the basic equations with a certain conservative force to those without an external force is considered. It is assumed that the spatial variation of the viscosity and thermal conductivity may be neglected and the dissipation function in the energy equation is also neglected. A simple example of a flow is given for a centrifugal force field by applying the transformation obtained. Several other transformations for more generalized conservative force fields are obtained for the case where the flow of two-dimensions is reduced to that of one-dimension by them.
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Jae-Tack Jeong, Moon-Uhn Kim
1988 Volume 57 Issue 3 Pages
856-865
Published: March 15, 1988
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Two-dimensional slow viscous flow through a converging nozzle composed of two semi-infinite plates is investigated on the basis of Stokes approximation. The flow is caused by a pressure difference between inner and outer region of the nozzle of an arbitrary angle. A formal expression for the flow is obtained by solving a pair of simultaneous Wiener-Hopf equations. Streamlines and stress distributions on each plate are determined by evaluating the formal expression. The relation between the discharge through the nozzle and pressure difference is given as a function of the angle of nozzle. The asymptotic behaviors of the flow at far field are also discussed.
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Toshiyuki Gotoh, Yukio Kaneda, Naoaki Bekki
1988 Volume 57 Issue 3 Pages
866-880
Published: March 15, 1988
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The Lagrangian renormalized approximation (LRA) and the Modified Lagrangian renormalized approximation (MLRA) are integrated numerically for decaying homogeneous isotropic turbulences in two and three dimensions. At moderate Reynolds numbers the results are in good agreement with the direct numerical simulations by Herring
et al. in two dimensions and with those by Orszag and Patterson in three dimensions. At high Reynolds numbers the one dimensional inertial and dissipation range spectra of the LRA and the MLRA agree well with the tidal channel data of Grant
et al. The comparison with the DIA, TFM, ALHDIA and SBALHDIA shows that the MLRA behavior is very close to that of the TFM.
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Haruo Shindo, Masashi Taono, Akiyoshi Nagata, Takeshi Tamaru
1988 Volume 57 Issue 3 Pages
881-886
Published: March 15, 1988
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A computational and analytical study of current density and magnetic field distribution in the reversed field pinch is presented. By using the kinetic model of Jacobson and Moses, the electron momentum transport across the magnetic field is formulated in terms of the perturbed distribution function with an analogy of enhanced cross-field heat transport in a stochastic magnetic field in tokamak. The current density obtained from the distribution function is used to give the magnetic field configuration through the Ampere’s law. The results showed, in the cylindrical geometry, that the momentum transport due to the stochastic magnetic field could make the current distribution spatially uniform and thus the self-reversal of the toroidal magnetic field occured. A further suggestion was made on an effect of the trapped electrons in local mirror of toroidal devices.
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Hiroshi Amemiya
1988 Volume 57 Issue 3 Pages
887-902
Published: March 15, 1988
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The effect of negative ions on the probe characteristics is studied theoretically and experimentally by using iodine and iodine-argon mixture plasmas. For a small ratio of negative ion to electron densities, the negative ion density and temperature can be determined from a sharp peak on the second derivative of the probe characteristics. At a higher ratio, the ratio of saturation currents at positive and negative probe biases should be used by calibrating the ratio with that of the case without negative ions. For a negative ion dominating plasma, a change of the Bohm criterion by negative ions should be considered and the parameters can be obtained from the probe characteristics which are nearly symmetric at positive and negative biases.
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Seio Sengoku, Akimasa Funahashi, Mitsuru Hasegawa, Katsumichi Hoshino, ...
1988 Volume 57 Issue 3 Pages
903-908
Published: March 15, 1988
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The additional increases both in the density
n and confinement time τ of the beam heated H-mode discharges are observed (
nτ value is improved by about 40%) when an electron cyclotron wave (ECW) resonating near the plasma boundary is applied. The ECW is shown to enhance wall fueling, to decrease the minimum heating power for switching the H-mode on or to extend the operational regime on
n−τ diagram of the H-mode discharges.
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Kiichiro Uchino, Takeharu Koga, Katsunori Muraoka, Mitsuo Maeda, Masan ...
1988 Volume 57 Issue 3 Pages
909-917
Published: March 15, 1988
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Measurements of atomic hydrogen density profiles in Heliotron E plasmas were performed, where attention was focussed on the anisotropy of the profiles in the poloidal cross section. Obtained penetration profiles of atomic hydrogen agreed well with the Monte Carlo code calculations of the penetration of Franck-Condon neutrals when averaged electron densities \bar
ne are larger than 10
19 m
−3. For \bar
ne<10
19 m
−3, however, experimental profiles decreased steeper than calculated ones. Degree of the anisotropy of the neutral profiles in the poloidal cross section was also found to change with the value of \bar
ne. Global particle confinement time τ
p was evaluated from the measured atomic hydrogen profile. The results showed that τ
p is around 20 ms for
B=1.9 T. In case of NBI plasma, τ
p increases as increasing the magnetic field strength, while it decreases as increasing the absorbed power.
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Ryuhei Kumazawa, Keizo Adati, Takashi Aoki, Hideki Fujita, Shigeru Hid ...
1988 Volume 57 Issue 3 Pages
918-928
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A scaling relation for the RF plugging potential is investigated in the line cusp plasma of a cusp-anchored mirror device, RFC–XX–M. The RF plugging potential is measured by two independent methods: One is measured by multi-grid energy analyzers and the other is deduced from the measured ion density under RF electrodes and the ion energy distribution in terms of the Boltzmann relation. These values agree well each other. The scaling relations of the RF plugging potential for an applied RF field and an ion density are investigated. These are compared with theoretical calculations. The RF plugging potential is formed under RF electrodes by the enhanced RF electric field associated with an eigenmode of the ion Bernstein wave with a perpendicular mode number,
n=1 and is in accordance with the ponderomotive potential expression.
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Yukiharu Ohsawa
1988 Volume 57 Issue 3 Pages
929-940
Published: March 15, 1988
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Resonant wave-particle interactions in magnetosonic shock waves are studied by theory and simulation. The number of ions trapped by a perpendicular laminar shock in a finite beta plasma is evaluated, and the amount of shock heating due to resonant ion acceleration is analytically obtained in terms of the Alfvén Mach number and upstream plasma parameters. Some effects of trapped ions on shock waves are also discussed. In addition, it is shown that a laminar oblique shock can reflect some electrons by a magnetic mirror effect, in spite of a large positive potential in the shock region. These theoretical predictions are confirmed by a fully electromagnetic particle simulation with full ion and electron dynamics in one spatial dimension.
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Koji Mio
1988 Volume 57 Issue 3 Pages
941-952
Published: March 15, 1988
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The numerical computations are done to study the envelope soliton propagation behavior for the nonlinear Alfvén waves propagating along the magnetic field in cold plasmas. It is confirmed that the four Korteweg-de Vries (KdV) types of envelope solitons can propagate stably through the interactions. It is also found that the different type solitons interact each other almost linearly though the same type solitons interact each other nonlinearly.
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Masahiro Nakazato, Nobuyoshi Wakabayashi, Tetsuo Kitai
1988 Volume 57 Issue 3 Pages
953-961
Published: March 15, 1988
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X-ray diffraction studies were made on LaCd, CeCd, and PrCd for temperatures between room temperature and 10 K. These compounds, which have the CsCl structure at room temperature, transform to structures with the tetragonal symmetry at low temperatures. On further cooling, satellite peaks having wave vectors (1/3, −1⁄3, 0) and (1/4, 1/4, 1/2) were found in CeCd below about 100 K. The symmetry of the lowest temperature phase is consistent with an orthorhombic structure. No new satellites were observed for PrCd, but the
c⁄
a-ratio changes abruptly at 20 K. The lattice instabilities associated with the phase transitions are discussed on the basis of a phenomenological model of lattice dynamics.
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Jun-ichi Igarashi
1988 Volume 57 Issue 3 Pages
962-968
Published: March 15, 1988
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Berry’s topological phase acquired during adiabatic evolution of systems is considered for transverse acoustic phonons in a helically wound rod of ferromagnetic material. Berry’s phase is calculated in the presence of magnon-phonon interaction and small deviation from cubic symmetry. A simple dependence of the phase on these perturbations is found, indicating that the presence of the magnon-phonon interaction is important to stabilize the phase against the destructive effect of the velocity-difference between two linearly-polarized transverse phonons. This dependence could be detected by measuring intensities of linearly-polarized waves with changing winding number of the helix.
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Kêitsiro Aizu
1988 Volume 57 Issue 3 Pages
969-977
Published: March 15, 1988
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Four possible types of ferroelectric incommensurate phases have been proposed hitherto. This paper proposes a fifth type. Assume for simplicity that the prototype is orthorhombic and centrosymmetric. Let the order parameters have wavevectors (±λ, ±μ, 0) and be four in number, where λ and μ are simple positive rational numbers. Denote these order parameters by
Qα,
Qα*,
Qβ and
Qβ*. A general term in the Fourier expansion of
Qα has the form
Qαmn exp i (
mhxx+
nhyy), where
m and
n are integers. It is important that the number of mutually independent
h’s is two, not one. Phases with |
Qαmn|=|
Qβmn| and |
Qα11=
Qα00=0 and
Qα10 or
Qα01≠0 are possible. They are a kind of incommensurate phases (appropriate to be called “demicommensurate”). Some of them are found to be ferroelectric, some ferroelastic, and some neither ferroelectric nor ferroelastic. These ferroelectric incommensurate phases are of the fifth type.
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Taizo Sasaki, Koichi Shindo, Komajiro Niizeki, Akira Morita
1988 Volume 57 Issue 3 Pages
978-987
Published: March 15, 1988
Released on J-STAGE: June 01, 2007
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The total energies of the rhombohedral A7 and the simple cubic (SC) phases of phosphorus are calculated within the local-density-functional formalism by using the norm-conserving pseudopotential. The calculated results successfully explain the phase transition from the A7 phase to the SC one under pressure. The calculated electronic structure of the metallic SC phase reveals that the bonding in this phase has an appreciable amount of covalency. It is also found that the stabilization of the SC structure under high pressure is due to be fact that the contribution of the electrostatic energy to the total energy increases on the compression. Moreover, it is shown that the absence of the core
d-orbitals of a phosphorus atom is very important in explaining the difference between phosphorus and other VB-elements in the phase transition under pressure.
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Yukiyasu Ozeki, Takuma Ishikawa
1988 Volume 57 Issue 3 Pages
988-990
Published: March 15, 1988
Released on J-STAGE: June 01, 2007
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The conductivity of binary lattice gases on a square lattice is investigated by the Monte Carlo simulation (MCS). The results of the MCS reveal systematic deviations in the percolation efficiency from those by the path probability method.
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Hidehiko Sugimoto
1988 Volume 57 Issue 3 Pages
991-996
Published: March 15, 1988
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In the temperature region where the quantum diffusion process is dominant, the hopping motion of light interstitials between neighboring sites with an energy difference is examined and their diffusion coefficient is calculated by using the Monte-Carlo method. It is found that the diffusion coefficient at low temperatures is of thermal activation type and its activation energy is strongly dependent on the lattice structure. This behavior is interpreted in terms of the critical-percolation probability in the bond-percolation theory.
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Sachio Ido, Shinichi Uchida, Koichi Kitazawa, Shoji Tanaka
1988 Volume 57 Issue 3 Pages
997-1005
Published: March 15, 1988
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Galvanomagnetic properties of a layered material, Ag
2F are investigated with particular emphasis on its anisotropy. Contrary to the previous observation, the conduction is found to be metallic in both parallel and perpendicular directions with respect to layer. It turns out that the transverse magnetoresistance is larger in magnitude when the magnetic field is applied parallel to the layer. In addition, quite large magnetoresistance is observed in the configuration where the current flows perpendicular to the layer and the field is parallel to it. Tlne analysis of these results in terms of two-carrier model suggests the presence of two types of carriers associated with the Fermi surfaces of different anisotropy. This agrees with the results of the recent LAPW band calculation.
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Prabir Pal, Dilip Ghosh, T. N. Misra
1988 Volume 57 Issue 3 Pages
1006-1012
Published: March 15, 1988
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Dark and photoconduction in astacin crystal in a sandwich cell has been studied as a function of applied field and temperature. The results suggest that a single discrete trapping level is involved in charge carrier generation and the dominant trapping level is different for dark and photoconduction. Space charge limited current theory has been used to evaluate various transport parameters. Linear excitation light intensity dependence of photocurrent suggests that the photo generation process is one photon process and is trap limited. Blue shift of the photoconduction action spectrum of astacin compared to its optical absorption spectrum with illumination throgh the positive electrode has been attributed to the difference in the rate of recombination of charge carriers at the surface and in the bulk when produced by radiation of different wavelengths.
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Takashi Ipp\={o}shi, Kôki Takita, Kohzoh Masuda
1988 Volume 57 Issue 3 Pages
1013-1023
Published: March 15, 1988
Released on J-STAGE: May 29, 2007
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This paper reports magnetic quantum oscillations of high electric field magnetoresistance due to nonradiative carrier recombination processes, i.e., Auger process and Shockley-Read process, in
n-Hg
1−xCd
xTe (MCT) (
x\simeq0.2). A new effect of magnetic quantum oscillation due to the electron trapping with emission of multiple LO-phonons associated with Shockley-Read process was observed together with the oscillation due to Auger process. Oscillations were observed successfully in a wide temperature range 4.2∼100 K, by the combination of a pulse technique and a second derivative method. The dominant origins of the oscillation can be clearly determined from the temperature dependence of the peak positions. In typical samples of MCT, Shockley-Read process governs the recombination at the lower temperature and Auger process at the higher temperature in the magnetic field. The temperatures of the crossing over of the two processes were determined for several samples with different carrier concentrations
n and different electron mobilities μ
H(
n=3×10
14∼2×10
15 cm
−3, μ
H=8×10
3∼2×10
5 cm
2/ V·s at 4.2 K).
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Shoichi Mase, Takashi Yasuda, Yuuji Horie, Mari Kusaba, Takeshi Fukami
1988 Volume 57 Issue 3 Pages
1024-1036
Published: March 15, 1988
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Phonon dispersion curves of YBa
2Cu
3O
7 have been calculated by making use of force constants deduced from those of (La
1−xSr
x)
2CuO
4 in a preceeding paper as well as our experimental results of ultrasonic attenuation and sound velocity for YBa
2Cu
3O
7. Results are resumed as follows. The intra-layer and inter-layer optic couplings between Cu and O atoms in the incomplete octahedron CuO
6 in YBa
2Cu
3O
7 give rise to the energies of 20∼27 meV at the B. Z. center. These optic phonons with desirable symmetry properties for causing strong electron-phonon interactions seem to be favorable to contribute to the high
Tc superconductivity. In particular, a large contraction of Cu–O side bond is sticking out from the linear Cu–O chain may be a very advantageous stituation to lead to a stronger electron-phonon interaction in YBa
2Cu
3O
7 than in (La
1−xSr
x)
2CuO
4.
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Teruo Matsushita
1988 Volume 57 Issue 3 Pages
1037-1043
Published: March 15, 1988
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The uniaxially compressional and tilt moduli of the fluxoid lattice obtained from the recent nonlocal theory have remarkable dispersion with respect to the wave number of deformation. However, the Lorentz force originating from the distorsion of these kinds in the fluxoid lattice is not dispersive, which implies that these elastic moduli have no dispersion as derived from the local theory. In order to examine this discrepancy, the relation between the displacement of the magnetic flux and that of the normal core of the fluxoid is investigated by using the quantization condition of the magnetic flux which has been disregarded in the nonlocal theory. The present result shows that the two displacements are the same. The resultant moduli have no dispersion and agree with the expressions of the local theory.
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Hiroshi Shimahara, Satoshi Takada
1988 Volume 57 Issue 3 Pages
1044-1055
Published: March 15, 1988
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An interplay between the superconductivity and spin density wave (SDW) is studied from the perturbative point of view based on the two dimensional Hubbard model. It is shown that the d-pairing superconductivity is induced by spin fluctuations near the SDW boundary. The superconducting transition temperature (
Tc) is found to be remarkably suppressed by the renormalization through the electron self-energy, and to be sensitive to the band parameters due to nesting of the Fermi surface and the presence of the van Hove singularity as well as to the Fermi energy and the on-site interaction. As a consequence
Tc is enhanced by the next-nearest-neighbour hopping integral. The relation between the present result and experiments of high
Tc superconductors is discussed.
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