Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
63 巻, 12 号
選択された号の論文の56件中1~50を表示しています
  • Hirohito Kiwata, Yasuhiro Akutsu
    専門分野: Mathematical methods in physics.
    1994 年 63 巻 12 号 p. 4269-4273
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We study the integrable SU(M) and SUq(M) quantum spin chains in the high-magnetic-field region at zero temperature. For M=4 we found second-order phase transitions at two different fields, H1 and H2. At both transition points, the magnetization curve versus magnetic field has cusps with discontinuities in the magnetic susceptibility. We clarify the mechanism of the phase transitions, from which we conclude that the SU(M) and SUq(M) quantum spin chains undergo (M-2) times field-induced phase transitions at zero temperature.
  • B. J. Bhattacharjee
    専門分野: Properties of specific particles and resonances.
    1994 年 63 巻 12 号 p. 4274-4277
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    It is shown from the analysis of the Periodic Table (PT) that it is possible to ascertain how many light unflavored (LU) and strange K mesons may exist in nature. Further it is possible to study almost all the properties (Viz. mass, spin, parity, G-parity, isotopic spin, charge conjugation, B, C, S and quark composition of mesons) of the elementary particles (EPS) and to state that mesons have some definite sum rules.
  • Yoshihiro Kuroiwa, Masahiro Nishimura, Ritsuko Nakajima, Hiroshi Abe, ...
    専門分野: Structure of liquids and solids; crystallography.
    1994 年 63 巻 12 号 p. 4278-4281
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    X-ray structural studies using single crystals have been performed for various concentrations x of intercalation compounds FexTiS2. Atomic arrangements of Fe atoms were found to be of short-range order in the spin-glass region and long-range order in the cluster-glass region. In x=0.15 (spin-glass), nearly spherical diffuse scattering was observed, whose maxima were at (1/2, , 0, , 1/2), (0, , 1/2, , 1/2), (1/2, , 1/2, , 1/2) and their equivalent positions. By means of an anomalous X-ray scattering technique, it was found that the short-range order of Fe atoms has a hexagonal symmetry. In x=1/4 (cluster-glass), 2√ 3a× 2a× 2c superlattice reflection was observed, and the crystal symmetry changed to monoclinic with the space group C2/m. In x=1/3 (cluster-glass), √ 3a× √ 3a× 2c superlattice reflection was observed, and the space group was P31c.
  • Masaki Takesada, Toshirou Yagi
    専門分野: Equations of state, phase equilibria, and phase transitions.
    1994 年 63 巻 12 号 p. 4282-4285
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The elastic anomaly in the first-order α -β phase transition in K2ZnBr4 has been studied by Brillouin scattering repeated many times on heating run through the transition point 458, K (Tt). A discrete distribution of the Brillouin frequency shift of the longitudinal acoustic mode in the β phase was observed in contrast to its unique value in the α phase below Tt. On the other hand, the transverse mode shows negligibly small anomalous behavior near Tt. The result is well explained by the elastic properties calculated in terms of the virtual intermediate states model proposed recently as a mechanism of the first-order α -β phase transition.
  • Yukio Noda, Itaru Tamura, Yoshihiro Kuroiwa, Tomoyuki Mochida, Tadashi ...
    専門分野: Equations of state, phase equilibria, and phase transitions.
    1994 年 63 巻 12 号 p. 4286-4289
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Low-temperature X-ray Weissenberg photographs of deuterated 5-bromo-9-hydroxyphenalenone (d-BrHPLN) were taken at 14.4, K to investigate the phase transition of an intramolecular and isolated hydrogen-bonded system composed of a tautomeric molecule. The system has one hydrogen bond in a rigid molecular skeleton, with the hydrogen atom being replaced by deuterium. The superlattice reflection is found at (h k+0.5 0) at 14.4, K, and it starts to deviate from the commensurate position above TC=22.8, K on heating. The transition is of the first kind and is characterized by a commensurate-incommensurate transition. The peak shift defined as 0.5+δ was also measured. Above TI=34.5, K, the profile becomes very broad and shows diffuse scattering behavior. The transition is of the second kind and is characterized by a so-called incommensurate-normal phase transition.
  • Yasuhiro Yoneda, Kiyoshi Sakaue, Hikaru Terauchi
    専門分野: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
    1994 年 63 巻 12 号 p. 4290-4293
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    X-ray diffraction measurements of single-crystal C60 film with the thickness of 800, Å (about 60, ML) were carried out at temperatures from 300, K to 20, K. An anomaly of the lattice parameter was observed at the transition temperature TC=240, K. The transition temperature of C60 film is 20, K lower than that of bulk crystal. The phase transition of C60 film was somewhat different from that in the bulk state.
  • Masatoshi Imada
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4294-4297
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Critical properties of the transition between the Mott insulator and quantum fluids are investigated by using the scaling theory. The Mott insulating phase and the quantum fluid phase of bi-component systems are categorized into several types depending on the existence of order and the type of excitation spectra. The critical exponents of the transition in multicomponent systems are discussed for various combinations of metal-insulator and superfluid-insulator transitions. For the generic transition between a genuinely multicomponent metal and the Mott insulator in d dimensions, the hyperscaling is satisfied with the correlation exponent ν =1/2d, the dynamical exponent z=2d, and the Drude weight exponent ζ =\frac32-\frac1d. It is argued that the upper critical dimension dc satisfies dc≥ 2. The above exponents are compared with ν =1/2, z=2, and ζ =\frac{d}2 for the transition to the band insulator. Critical properties of the energy gap, the compressibility and other quantities are also discussed.
  • Hideo Yoshioka, Yoshikazu Suzumura
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4298-4301
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Two chains of spinless Tomonaga model coupled by a transverse hopping are investigated in terms of phase Hamiltonian where separation of Fermi momentum in the presence of the hopping is taken into account explicitly. It is shown that there appears a gap in one of the two excitations by using a renormalization group method. As a result, correlation of charge density wave with interchain ordering and out of phase between the chains (superconductivity with intrachain ordering and in phase between the chains) becomes the most dominant one in the case of the repulsive (attractive) intrachain interaction.
  • Hiroshi Sawa, Masafumi Tamura, Shuji Aonuma, Minoru Kinoshita, Reizo K ...
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4302-4305
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Li+-doping in the Cu salt of deuterated DMe-DCNQI-d7 has shown drastic effects on electrical and magnetic properties. Undoped (DMe-DCNQI-d7)2Cu exhibits a first-order metal-insulator (M-I) transition at 80, K. A small amount of Li+-doping suppresses the M-I transition. The M-I-M (reentrant) transition, which is similar to that in selectively deuterated (DMe-DCNQI)2Cu, appears in a narrow region of Li content x. The x-T phase diagram under ambient pressure well reproduces the P-T phase diagram of the (DMe-DCNQI)2Cu system. This doping effect is explained by the change in charge transfer amount from metal ions to DCNQI molecules. The effect of pressure or deuteration on the M-I transition in the DCNQI2Cu system is generally understood from this viewpoint.
  • Akinobu Kanda, Shingo Katsumoto, Shun–ichi Kobayashi
    専門分野: Electronic transport in condensed matter.
    1994 年 63 巻 12 号 p. 4306-4309
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We have measured transport properties of a two-dimensional array of small Josephson junctions with normal-state tunneling resistance RN=60, kΩ . The zero-bias resistance showed a so-called square-root-cusp-type temperature dependence in a limited temperature range and the current-voltage characteristics were nonlinear at lower temperatures. We interpret these features as a precursor of the charge Kosterlitz-Thouless-Berezinskii transition with a finite screening length.
  • Yositake Takane
    専門分野: Electronic transport in condensed matter.
    1994 年 63 巻 12 号 p. 4310-4313
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Sample-to-sample fluctuations of the Josephson current in superconductor-dirty normal metal-superconductor junctions are studied numerically using a tight-binding model. Particular attention is given to the cases where the correlation energy of the normal metal is smaller than the superconducting pair potential. It is found that the amplitude of the critical-current fluctuation is of order of the correlation energy. This result is in qualitative agreement with the theory of Al'tshuler and Spivak.
  • Manfred Sigrist, Yong Baek Kim
    専門分野: Superconductivity.
    1994 年 63 巻 12 号 p. 4314-4317
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    A new experiment is proposed to probe the time-reversal symmetry of a superconductor. It is shown that a time-reversal symmetry breaking superconductor can be identified by the observation of a fractional flux in connection with a Josephson junction in a special geometry.
  • Tadao Kasuya
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4318-4321
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Anomalous temperature dependence of Knight shift with a peak structure including pressure effect in CeP and CeAs was studied based on the magnetic polaron model. It was shown that the simple crystal field model can induce a peak but cannot reproduce the whole temperature dependence consistently. On the other hand, the magnetic polaron model can reproduce the entire structure consistently including the pressure effect, in particular in CeP, but some problem remains in CeAs.
  • Satoshi Fujimoto, Norio Kawakami
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4322-4326
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The one-dimensional Kondo lattice model is investigated by using bosonization techniques and conformal field theory. In the half-filled band, the charge and spin gaps open for the anti-ferromagnetic Kondo coupling. Away from half-filling, the paramagnetic metallic state is characterized by the fixed point of Tomonaga-Luttinger liquid with the large Fermi surface in accordance with the conclusion of Ueda et al.
  • Shoji Yamamoto
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4327-4330
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Ground-state properties of S=1 antiferromagnetic Heisenberg chains with bond alternation, Η=J, ∑ i, {1-(-1)iδ } Si· Si+1, are studied by a quantum Monte Carlo method. Spin correlation between chain ends on the open chain appears for δ <0.25, while it vanishes for δ ≥ 0.25. At δ ~= 0.25, the spin correlation length has a peak and the S=1/2 edge states for the open chain disappear. The fourfold degeneracy of the ground state of the open chain holds for δ <0.25, while it is removed for δ ≥ 0.25. All the results support the continuous phase transition at δ ~= 0.25 demonstrated in the previous works.
  • Masahiro Matsumura, Hiroshi Yasuoka, Yutaka Ueda, Hideki Yamagata, Yut ...
    専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 年 63 巻 12 号 p. 4331-4334
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The nuclear spin-lattice relaxation rate 1/T1 and the indirect nuclear spin-spin relaxation rate 1/T2g for 63Cu in La2CuO4 (TN=312, K) were reexamined from 400, K to 1000, K, expanding the temperature range of the first observation by Imai et al. The temperature dependence of 1/T1 is in good agreement with the previous result, while 1/T2g decreases more rapidly with temperature. The temperature dependences of both 1/T1 and 1/T2g closely follow the renormalized classical (RC) formula below about 600, K, but deviate from the RC prediction above 600, K. The scaling relation between 1/T1 and 1/T2g was not confirmed above 600, K, in conflict with the theoretical prediction for the quantum critical (QC) regime. Hence, we argue that the deviation from the RC formula above 600, K does not necessarily correspond to a crossover from the RC to the QC regime.
  • Tetsuya Matsuno, Yuujirou Imada, Kiyoshi Toko, Kaoru Yamafuji
    専門分野: Biophysics.
    1994 年 63 巻 12 号 p. 4335-4337
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Effects of a distribution of natural frequencies of oscillatory elements constituting a phase memory system are investigated theoretically. It is found that the distribution causes considerable effects on the storage capacity (α c) and on the dynamics of the retrieval states. The obtained state diagram shows the decrease of α c with the introduction of the distribution. The distribution also leads to an oscillation of the overlap.
  • K. H. Chung, P. M. Hui
    専門分野: Other areas of research of general interest to physicists.
    1994 年 63 巻 12 号 p. 4338-4341
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Traffic flow problems in one-dimensional inhomogeneous media are studied using cellular automaton models. The effects of (i) a single impurity site, at which a car takes longer time to pass through, in an otherwise uniform medium, (ii) the addition of a finite concentration of overtaking sites that can accomodate two cars at the same time, and (iii) the presence of both an impurity site and overtaking sites are studied. Analytic expressions for the average car velocity and flux in the long time limit as a function of car density are derived.
  • Takeshi Iizuka
    専門分野: Mathematical methods in physics.
    1994 年 63 巻 12 号 p. 4343-4349
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Nonlinear waves in a one-dimensional periodic system are investigated. If the system is linearized, it has Bloch type solutions. It is shown that envelopes of the Bloch wave obey the nonlinear Schrödinger equation. Therefore, soliton propagations are observed in the system. Our method is applicable to many nonlinear periodic systems.
  • Ll. Bel, J. Martín, A. Molina
    専門分野: Relativity and gravitation.
    1994 年 63 巻 12 号 p. 4350-4363
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We give a definition of rigid congruences in both General and Special Relativity, and we try to make the definition plausible. To this end we recall Fermat's principle in General Relativity and we show that this principle allows us to reinterpret the “quotient metric” as the quadratic form which defines the optical length in a gravitational field. We apply the definition to the Earth-Sun system in the post-Newtonian approximation. Furthermore we compute the Fermat tensor and the corresponding relative variation of the speed of light in a Michelson-Morley like experiment performed on the Earth's surface. According to all measurements to date, this quantity is extremely small (10-13).
  • Tomejiro Yamagishi
    専門分野: Kinetic and transport theory of fluids; physical properties of gases.
    1994 年 63 巻 12 号 p. 4364-4372
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The ballooning mode equation has been derived by a kinetic approach with an uniform radial electric field and electron collision effects in a tokamak. Applying an averaging method an analytical form of the growth rate has been obtained, which has been applied for the derivation of the diffusion coefficient. At the L-H transition, although the cengrifugal force due to plasma rotation destabilizes the ballooning mode, the stabilization by the change of density profile is stronger, and the plasma state may change from the ideal ballooning L-mode state to the H-mode state in the second stability region.
  • E. Lazzaro, G. Lampis, A. Bernardinello
    専門分野: The physics of plasmas and electric discharges.
    1994 年 63 巻 12 号 p. 4373-4378
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The inviscid drift tearing modes dispersion relation is a singular limit of the viscous theory. We show that a finite viscosity leads to dissipative coupling of branches of the drift tearing mode dispersion relation. As a consequence, linear magnetic field reconnection perturbations appear unstable also at large drift frequency. The effects present analogies with the theory of the Orr-Sommerfeld equation for viscous fluids. Applicability to edge localized resistive modes in a tokamak is suggested.
  • Kirti Prakash, Seema Manchnda
    専門分野: The physics of plasmas and electric discharges.
    1994 年 63 巻 12 号 p. 4379-4385
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The effect of the finite Larmor radius (FLR) of ions on the thermal instability of a plasma in porous medium is investigated. The case with vertical magnetic field is discussed. It is found that the presence of finite Larmor radius and magnetic field introduces oscillatory modes which otherwise do not exist. When the instability sets is as stationary convection, the finite Larmor radius is found to have a stabilizing effect. The medium permeability has destabilizing or stabilizing effect under certain condition in the presence of FLR effect whereas in the absence of FLR effect the medium permeability always has destabilizing effect. Similarly, magnetic field has stabilizing or destabilizing effect under the same above condition in the presence of FLR effect whereas in the absence of FLR effect, magnetic field always has stabilizing effect and medium permeability has destabilizing effect.
  • Ryo Sugihara, Kaoru Yamanaka
    専門分野: The physics of plasmas and electric discharges.
    1994 年 63 巻 12 号 p. 4386-4395
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The cyclotron motion of ion in a nonuniform electromagnetic wave is analysed using the multiple-time-scale-expansion method. A set of nonlinear equations which describes the evolutions of the gyroradius ρ, the gyrophase β, and the average velocity ‹ vz› along the magntic field B0 is obtained. The set is found exactly integrable and three conservation relations are obtained for an arbitrary harmonic among ρ, β, ‹ vz› and the drift coordinates perpendicular to B0. The theory includes the one obtained for the fundamental harmonic and a uniform amplitude wave and is also applied to ion acceleration in a non-uniform field near an antenna used in an ion-cyclotron-range-of-frequencies (ICRF) wave heating. Thus the theory seems to be more rigorous and general than the previous ones.
  • Yasushi Matsunaga, Tomokazu Kato
    専門分野: The physics of plasmas and electric discharges.
    1994 年 63 巻 12 号 p. 4396-4405
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Nonlinear oscillation that indicates chaotic behavior at low frequency in a gas discharge plasma is investigated by analytic and numerical solutions. The electric field in plasma is determined through the Poisson equation by assuming charge distribution: ions distribute spatially uniform, beam electrons from hot cathode are described by an exponentially decreasing distribution, and plasma electrons are in thermal equilibrium and described by the Boltzmann distribution. The electrostatic potential that is obtained analytically by using linear approximation contains the Debye shielding effect. Low frequency motion of the ions in this electric field is calculated numerically. Period-doubling bifurcation and chaotic oscillation are obtained for a region of parameters and they agree with the experimental results qualitatively.
  • Satoru Sakakibara, Hiroshi Yamada, Akira Ejiri, Katsumi Ida, Keisuke M ...
    専門分野: The physics of plasmas and electric discharges.
    1994 年 63 巻 12 号 p. 4406-4421
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The magnetic fluctuations with the frequency f≤ 100, kHz in NBI heated plasmas have been investigated in the Compact Helical System (CHS). The observed coherent fluctuations are identified as global modes with m≤ 4, n≤ 3. The dependences of these modes on the magnetic configuration and the plasma beta are well interpreted phenomenologically by the theoretical models of the resistive and the ideal interchange modes. Both these modes and the incoherent fluctuations increase with the beta value ‹ β dia›, however, saturate when ‹ β dia› reaches about 1
  • Shoji Kashida, Tetsuya Hori, Kazuo Nakamura
    専門分野: Structure of liquids and solids; crystallography.
    1994 年 63 巻 12 号 p. 4422-4426
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The structure of a bismuth based oxide, Bi2O3:V2O5=9:1, has been studied by X-ray diffraction. This crystal has a fluorite type superstructure with 3× 3× 3 subcells. Vanadium atoms are located at every third layers along the [111] axis and occupy the third neighbor sites of the fcc lattice. The oxygen vacancies are concentrated at nearest neighbor sites of the vanadium atoms.
  • Kazuo Suzuki
    専門分野: Structure of liquids and solids; crystallography.
    1994 年 63 巻 12 号 p. 4427-4434
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The approximate model of the structure of precipitates in mixed crystals of NaF containing 1, mol
  • Setsuko Mukai, Masahiro Nakagawa
    専門分野: Mechanical and acoustical properties of condesed matter.
    1994 年 63 巻 12 号 p. 4435-4442
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    On the basis of a continuum theory of compressive SmC*, we shall investigate a nucleation of disclinations, under a DC electric field, accompanied with the layer relaxation phenomenon between a couple of antiparallel chevrons. From the two-dimensional analyses of the layer structures and the c-director configuration with a screw disclination between a couple of anti-parallel chevrons, it is found that a screw disclination, which move depending on the applied electric field strength, may be produced under a certain electric field, and that such threshold field strengths critically depend on the molecular tilt angle, the cell thickness and an elastic constant. In addition one finds that there also exists a threshold for the layer reversal under a relatively high electric field.
  • Kêiichiro Aizu
    専門分野: Equations of state, phase equilibria, and phase transitions.
    1994 年 63 巻 12 号 p. 4443-4445
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    This paper complements a previous one [J. Phys. Soc. Jpn. 63 (1994) 1018]. Let Φ denote the free energy function. Let the order parameters be two real variables Qα and Qβ . The previous paper studied cases where {Φ} contains term ∂ z(Q2α -Q2β ) or ∂ z(Qα Qβ ). These cases contrast with a case where {Φ} contains term Qβ zQα -Qα zQβ . The present paper investigates the latter case. Let ĥ and U denote the wavenumber and amplitude of prototype undulation, respectively. Let h denote the wavenumber of undulation of the order parameters in the ferroic phase. In the present case, unlike in the previous cases, h separates from ĥ. The expression of dependence of h on U and the expression of dependence of the transition temperature on both U and ĥ are deduced. The former expression presents the criterion for judging whether | h| increases or decreases with increasing U.
  • Hiroyasu Toyoki
    専門分野: Thermal properties of condensed matter.
    1994 年 63 巻 12 号 p. 4446-4450
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Dislinations and monopoles in the phase ordering of three-dimensional nematic liquid crystals follwing a quench are numerically investigated. The total length of dislinations decreases as L-- t-0.95± 0.07. Monopoles are not detected except in the early transient regime. It is found that monopoles change to a ring disclination, and rings reconnect to shrink to nothing.
  • Koji Kobayashi, Ko Sugihara, Hisashi O{shima}, Takuro Tsuzuku
    専門分野: Thermal properties of condensed matter.
    1994 年 63 巻 12 号 p. 4451-4455
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Thermoelectric power in the c-direction (Sc) of iodine monochrolide-graphite intercalation compounds (ICl-GICs) exhibits a gradual slope change around 80--100, K, though above and below the temperature range Sc is nearly linearly temperature-dependent. This behavior implies that the major contribution to Sc comes from the diffusion term (Sd), and the absence of the phonon drag term (Sp) in contrast with the in-plane component (Sa) is due to the very weak interlayer interaction. The slope change is ascribed to the change of the energy dependence of Γph(E) with temperature, where Γph(E) is the scattering rate of carriers due to the in-plane phonons. Γph(E) and pph≡ -E(d/dE), log, Γph(E), which are included in the expression of Sc, are calculated. The calculation can provide a qualitative explanation of the observed result of stage-1 compound.
  • Yoshitaka Michihiro, Akihiko Itabashi, Toshihiro Yamanishi, Tatsuo Kan ...
    専門分野: Transport properties of condensed matter (nonelectronic).
    1994 年 63 巻 12 号 p. 4456-4462
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The complex impedance in (Bi2O3)1-x(WO3)x (x=0.23 and x=0.25) in the δ * phase has been measured over the temperature range 300, K to 740, K and the frequency range 500, Hz to 20, MHz. The electrical conduction is found to be due to the thermally activated motion of oxygen ions. The frequency dependence of the impedance shows the characteristic features of the universal dielectric response and is described by an empirical Jonscher type relaxation function. The activation energy is estimated for the hopping motion of the oxygen ions. The diffusive motion of the mobile ions is discussed on the basis of the cage-effect jump-relaxation model.
  • Masahiko Higuchi, Hiroshi Yamagami, Akira Hasegawa
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4463-4474
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The energy band structure, particularly the Fermi surface, is calculated for fcc Th by a self-consistent, relativistic augmented-plane-wave method with the exchange and correlation potential in a local-density approximation. The extremal cross-sectional area of the Fermi surface is calculated carefully as a function of the direction of the normal on the {100} and {110} planes, which has been so far calculated only in three high-symmetry directions, and compared with the experimental results for the de Haas-van Alphen (dHvA) effect measured by Boyle and Gold (1969). As a result, it becomes possible to identify the origin of many dHvA frequency branches much more clearly. In addition, a new assignment of the theoretical and the experimental dHvA frequency branches is proposed, and the existence of several new dHvA frequency branches is predicted also.
  • Tetsuya Mutou, Dai S. Hirashima
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4475-4488
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We study the symmetric periodic Anderson model in infinite dimensions by the selfconsistent second order perturbation theory. After solving the selfconsistent equations for the Green's functions, we calculate dynamical charge- and spin susceptibilities and dynamical conductivity as well as thermodynamic quantities and resistivity. Dynamical conductivity is also calculated by another second order perturbation theory, the iterated perturbation theory. At T=0, density of states has a gap around the chemical potential. We also find that at T=0 a gap appears in dynamical response functions. The resistivity is found to obey an activation-type temperature dependence at low temperatures. The gaps in the spin- and charge excitation spectrum are found to be equal in magnitude, and also to be equal to the gap in the density of states. On the other hand, the gap in the dynamical conductivity is larger because it is a direct gap. We further study the temperature dependence of these quantities, and show how a gap evolves as the temperature decreases. Furthermore, we discuss relations to experimental results on the so-called Kondo insulators.
  • Shin"ichi Higai, Hitoshi Sumi
    専門分野: Electron states in condensed matter.
    1994 年 63 巻 12 号 p. 4489-4498
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    When excitons (or electrons) have only one-dimensional freedom of motion on a discrete lattice, free states are always unstable, irrespective of the strength of the exciton-phonon (short-ranged) interaction. Excitons spontaneously relax into self-trapped (S) states, distorting the lattice. Two types of S states are realized: One is a large-radius type associated with a spatially extended lattice distortion, while another is a small-radius type associated with a spatially contracted distortion. As the interaction strength increases, the lowest S state changes its character abruptly, although continuously, from the former to the latter. This result is rigorous within the adiabatic approximation, calculated with a method presented previously by the present authors [H. Sumi and S. Higai, J. Phys. Soc. Jpn. 62 (1993) 1500].
  • Masayoshi Tonouchi, Tatsuro Miyasato, P. Hawker, T. S. Cheng, V. W. Ra ...
    専門分野: Electronic transport in condensed matter.
    1994 年 63 巻 12 号 p. 4499-4505
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We have studied the edge magnetoplasmon (EMP) in a GaAs/AlGaAs two-dimensional electron gas (2DEG) system under conditions where the quantum Hall effect (QHE) is not observed; we call this a classical EMP. The classical EMP's are excited in a 2DEG disk by radio frequency electric field excitation (≤ 1, GHz) in a high magnetic field B (≤ 5, T) with the 2DEG sheet carrier density ns between 2× 1015, m-2 and 1× 1016, m-2. The resonant frequency is found to be almost proportional to ns and inversely proportional to B, which agrees quantitatively with the theory proposed by Volkov and Mikhailov, Sov. Phys.-JETP 67 (1988) 1639 by assuming the effective dielectric constant ε\circ =(1+ε GaAs)/2 where ε GaAs is appropriate to the GaAs. A comparison of the experimental results with the calculations revealed that the electron mobility plays an important role in the definition of the EMP frequency.
  • Tsuyoshi Ueta
    専門分野: Electronic transport in condensed matter.
    1994 年 63 巻 12 号 p. 4506-4513
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Behavior of an electron beam injected from a waveguide into a semi-infinite two-dimensional plane in magnetic fields is quantum-mechanically studied. When the ratio of transverse to longitudinal momenta is small in the waveguide and the wavelength is small in comparison with the width of the orifice, electron waves propagate along classical trajectories. When this ratio or wavelength is large, the substructure in the electron density appears in the vicinity of the reflecting points. The substructure grows with the distance from the orifice and the distance from the orifice to the point where the substructure becomes visible is independent of magnetic field.
  • J. J. Lin, Ren–ichi Yamada, Shun–ichi Kobayashi
    専門分野: Electronic transport in condensed matter.
    1994 年 63 巻 12 号 p. 4514-4520
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We have measured the magnetoresistances in ≈ 30-Å-thick Cu-particle films between 1.2 and 4.2, K and in magnetic fields H up to 6, T, with sheet resistances R_{\lang}(4.2, K) of the films varying from ≈ 8, kΩ to 2, MΩ . We find that the magnetoresistances are positive, exhibiting broad maxima, at low H, while they change sign and become negative at high H (typically, around 4, T). The magnitudes of the normalized magnetoresistances, ΔR_{\lang}(H)/R_{\lang}(0)=[R_{\lang}(H)-R_{\lang}(0)]/R_{\lang}(0), are of the order of a tenth of a percent or smaller, depending on the values of R_{\lang}. Particularly, the magnetoresistances are highly isotropic, regardless of the orientation of H being applied parallel or perpendicular to the film plane. These observations are closely connected with the fine-particle structure of our films, and can be qualitatively explained in terms of Zeeman effects in producing magnetoresistances in strongly localized, interacting electrons.
  • Katsuaki Kodama, Shin–ichi Shamoto, Hiroshi Harashina, Masatoshi ...
    専門分野: Superconductivity.
    1994 年 63 巻 12 号 p. 4521-4528
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Neutron inelastic scattering measurements have been carried out on Y0.52Pr0.48Ba2Cu3O7 with the superconducting transition temperature Tc~= 20, K. From the spectral weight function χ ''(q, , ω ) of the Cu-spin excitations in the CuO2 planes, the reduction of the hole-carrier concentration and the degree of the randomness induced by the substitution of Pr for Y are estimated. These results present evidences that the model of a hole-trapping by the hybridized states of the Pr4f and O2pπ orbitals proposed by Fehrenbacher and Rice [Phys. Rev. Lett. 70 (1993) 3471] provides an appropriate explanation of the experimental results associated with the well-known Tc-suppression of R1-xPrxBa2Cu3O7 (R=Y or various lanthanide elements) by the Pr-doping.
  • Nobuyuki Katoh, Masatoshi Imada
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4529-4541
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The quantum phase transition between a spin gap state and an antiferromagnetic phase is investigated. We study S=1/2 antiferromagnetic Heisenberg chains coupled by antiferromagnetic interchain interaction. The intrachain exchanges have alternating strength. The phase boundary between the antiferromagnetically ordered phase and a spin gap phase is also obtained in a parameter space of the amplitude of the interchain coupling and the dimerization. The spin-wave approximation substantially overestimates the antiferromagnetic phase. The competition between the long range order and the spin gap is examined in detail. We estimate a variety of critical exponents at the transition, namely, exponents ν, θ and z defined as the exponent of the correlation length, the magnetization curve and the dynamical exponent, respectively. From the quantum Monte Carlo simulation, the exponents ν, θ and z are estimated to be unity. The exponents ν and θ are different from the estimated values in one dimension. It suggests that the universality changes due to the dimensionality change. In our estimates, the exponent ν does not agree with the prediction from three dimensional classical Heisenberg model. We also discuss the relevance of our result to spin-Peierls systems with lattice distortion.
  • Shinichi Itoh, Kazuyoshi Yamada, Masatoshi Arai, Yasuo Endoh, Yoshikaz ...
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4542-4549
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Inelastic neutron scattering experiments were performed using a chopper spectrometer, MARI, to elucidate the spin dynamics of two-dimensional quantum Heisenberg antiferromagnets of both La2CuO4 (S=1/2) and La2NiO4 (S=1) over a wide range of both momentum and energy transfers. The spin dynamics at low temperatures well below the Néel temperature was confirmed to essentially follow two-dimensional spin-wave theory. A quantitative analysis based on spin-wave theory showed that the magnetic form factor determined from the spin excitation is well described by the calculated free-ion magnetic form factor.
  • Ikuo Nakai, Tomoki Fukagawa
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4550-4555
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We present detailed investigation of the temperature dependence of the magnetization for amorphous Gd65Co35 below 340, K in magnetic fields up to 5.27, T. The paramagnetic susceptibility follows the Curie-Weiss law. We experimentally find that T2.00± 0.05 is the functional form of another dominant contribution to the temperature dependence of the magnetization than the spin wave term T3/2. These T2 and T3/2 terms are interpreted as longitudinal and transverse fluctuations in the local moment derived from polarization of the spin bands. The longitudinal fluctuation comes from itinerant character of 3d electrons in Co atoms.
  • Naoshi Ikeda, Kay Kohn, Hijiri Kito, Jun Akimitsu, Kiiti Siratori
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4556-4564
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We report the frequency and the temperature dependence of the dielectric constant of polycrystalline ErFe2O4-δ with different degrees of oxygen deficiency δ . A large dielectric relaxation, with the order of magnitude of 104 and nearly of the Debye type, is observed in the magnetically ordered states within the temperature and frequency ranges of 150, K to 290, K and 1, kHz to 3, MHz, respectively. The dispersion is larger in the sample with more oxygen deficiency. From the temperature dependence of the characteristic frequency, we conclude that the elementary process of the dispersion is related to electron hopping between Fe2+ and Fe3+ ions. A large value of the dielectric constant is consistent with the existence of spontaneous polarization in the magnetic phases of this oxide. We propose that the motion of the polarization domain boundaries is a determining factor of low-frequency dielectric constant.
  • Ken"ichi Takano
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4565-4572
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Excited states with total spin 1 of a series of one-dimensional Heisenberg models are examined by a variational method. These models have short-range exchange interactions which decrease linearly with the distance between spins. Their ground states are exactly the same complete dimer states as those of the Majumdar-Ghosh model. Variational wave functions for the excited states are constructed by modifying the ground states. Excitation spectra and excitation gaps are obtained in analytic forms for the models with various interaction ranges. The excitation gap increases with increasing interaction range and saturates to a constant value.
  • Haruhiro Hiraka, Yasuo Endoh
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4573-4582
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The static magnetic properties near the Curie temperature in CoS2 have been thoroughly studied by using various experimental techniques from high quality single crystals, which were grown by the chemical transport technique. A very small anisotropy in magnetization confirms that CoS2 is the best system to apply the Heisenberg Hamiltonian. The critical indices obey the static scaling hypothesis, which indicates negligible effect of the temperature-induced local moment on the ferromagnetic transition. However, the static critical properties suggest that the magnetic transition is close to the tricritical point, although the magnetic transition in CoS2 is continuous.
  • Taku Sato, Hiroaki Kadowaki, Hiroji Masuda, Katsunori Iio
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4583-4596
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Neutron diffraction experiments on the Heisenberg antiferromagnet MnBr2 were performed to study the successive magnetic phase transitions (TN1=2.32, K, , TN2=2.17, K). The magnetic structure in the intermediate phase is found to be a transverse sinusoidally-modulated structure with an incommensurate modulation vector qic~= (0.207, , 0, , 0.387), which varies as a function of temperature. At TN2 a first-order transition takes place from the incommensurate structure to the commensurate (qc=(1/4 {1em}0 {1em}1/4)) structure. These phase transitions are successfully accounted for using mean-field theory based on a Hamiltonian which consists of six exchange interactions and the dipole interaction.
  • Yasuaki Oohara, Katsunori Iio
    専門分野: Magnetic properties and materials.
    1994 年 63 巻 12 号 p. 4597-4603
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    Short-range spin ordering of RbNi1-xCoxCl3 with the substitutional concentration x smaller than 0.05 was studied by the birefringence technique. This mixed system belongs to an Ising-like Heisenberg antiferromagnet on a triangular lattice and has successive phase transitions. The upper Néel temperature, TN1, goes up and the lower one, TN2, goes down as an effective Ising anisotropy is amplified with gradual substituting of Ni2+ by Co2+. The temperature dependence of the birefringence Δnac for light propagating perpendicular to the c-axis is sensitive to the Co2+ concentration x at temperatures near the phase transition points. How the Ising anisotropy affects the short-range ordering of an Ising-like Heisenberg antiferromagnet on a triangular lattice is discussed by analyzing the temperature dependence of the observed birefringence.
  • Shigeru Takagi
    専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 年 63 巻 12 号 p. 4604-4611
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    The microscopic magnetic properties of UP with the cubic NaCl-type structure have been investigated by 31P NMR in the magnetically ordered state. 1/T1 is extraordinarily large in the single-Q type-I phase (T0≅ 22.5, KN≅ 122, K), and shows about two orders of magnitude abrupt decrease through the single-Q↔ double-Q phase transition at T0. Below about 4, K in the double-Q type-I phase (T0), 1/T1 shows a Korringa-like temperature-dependence, which corresponds qualitatively to a 5f-derived γ T term in the specific heat. We discuss this behavior as a clear indication of the existence of 5f-derived very-low-energy magnetic excitations even in the ordered state, and an incipient heavy-electron character of the compound is concluded. We also present a simple qualitative model of a system of exchange-coupled Kondo impurities under internal exchange (or molecular) field in order to discuss the origin of these excitations.
  • Cheol Eui Lee, J. R. Gaines
    専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1994 年 63 巻 12 号 p. 4612-4615
    発行日: 1994/12/01
    公開日: 1999/10/01
    ジャーナル 認証あり
    We have studied the echo decays in high J=1 concentration solid hydrogen (H2) and deuterium (D2) using 1H NMR. In solid H2, where the ortho-para conversion is rapid, quick measurements were made possible by computer batch files containing pulse programs. In solid D2, 1
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