Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 57, Issue 5
Displaying 1-50 of 55 articles from this issue
  • Shibani Sen, A. Roy Chowdhury
    1988 Volume 57 Issue 5 Pages 1511-1513
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    We have shown that it is possible to formulate a Bethe-Ansatz-type solution for a quantum mechanical nonlinear Schrödinger equation in an external electric field.
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  • Yuji Nakawaki
    1988 Volume 57 Issue 5 Pages 1514-1517
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    It is shown that in an infinite volume, the nonlinear Schrödinger model (repulsive case) is equivalent to a nonrelativistic free-fermion field theory. This is accomplished by expressing the Hamiltonian, momentum operator and particle density operator in terms of free-fermion operators constructed out of reflection operators. It is also shown that a thermodynamic trace of the density operator can be consistently regularized so as to yield a Fermi-Dirac distribution.
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  • Yoshio Yamaguchi
    1988 Volume 57 Issue 5 Pages 1518-1521
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Parity-violating nuclear forces (PVNF) can be studied by making use of very-low-energy neutrons (\lesssim10 eV) with definite helicities scattered by nuclei. Such processes can be expressed in terms of eigenphase shifts and mixing parameters and can be used to explore the nature of parity-violating effects in nuclei.
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  • Yoshio Yamaguchi
    1988 Volume 57 Issue 5 Pages 1522-1524
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    A comprehensive parameterization of parity-violating n-139La scattering processes is given in terms of the minimum set of physical quantities, the eigenphase shifts for s-wave and resonant p-wave neutrons and the parity-mixing parameter, based on the S-matrix theory. This method can be applied to other nuclear cases which exhibit parity violation.
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  • Yoshio Yamaguchi
    1988 Volume 57 Issue 5 Pages 1525-1527
    Published: May 15, 1988
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    Two viewpoints are presented for large-parity-violating neutron-139La scattering. One is to attribute it to a large fluctuation of parity-mixing in the particular p-resonance at 0.74 eV within the framework of the standard model (CP-conserving). The other viewpoint relates it to the existence of new parity-violating (CP-conserving or nonconserving) nuclear interactions whose strengths are intermediate to those of electromagnetic and weak interactions. It is important to check experimentally whether or not n-139La scattering respects CP invariance.
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  • Nobuo Kobayashi, Takao Kojima, Yozaburo Kaneko
    1988 Volume 57 Issue 5 Pages 1528-1531
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Helium cluster ions 4Hen+ (2≤n≤15) have been formed in a drift tube. Information about binding energy, ΔEn=EnEn−1, has been obtained. The binding energy drastically decreases at n=4, then gradually decreases with increasing n. Steplike changes have also been observed between n=10 and 11 and n=14 and 15, which indicates that the cluster sizes n=10 and 14 are magic numbers. Geometrical structures of He10+ and He14+ are discussed.
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  • Kiyoshi Yamamoto, Iwao Hosokawa
    1988 Volume 57 Issue 5 Pages 1532-1535
    Published: May 15, 1988
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    The decaying isotropic turbulence starting with a typical initial energy spectrum was numerically investigated by the spectral method for Reynolds numbers 50–500, using up to 1283 grid points. The microscale Reynolds number reached at a fully developed state was \lesssim100. Only the periodic boundary condition was set on the surfaces of the cube which contained the turbulence. As a result, the Kolmogorov spectrum law and other interesting characteristics of the turbulence were found, including the perspective of intermittent strong-vorticity regions randomly distributed in a fully developed turbulence.
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  • Yutaka Okabe, Komajiro Niizeki
    1988 Volume 57 Issue 5 Pages 1536-1539
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    The ferromagnetic Ising model on the dual Penrose lattice is simulated by the Monte Carlo method. Using a phenomenological Monte Carlo renormalization group based on finite-size scaling, the critical temperature and the magnetic critical exponent are estimated as TcJ=2.150±0.006 and yH=1.88±0.02. It is shown that the duality relation, sinh (2JTc) sinh (2JTc*)=1, between the critical temperature of the Ising model on a lattice Tc and that on its dual lattice Tc* holds for a quasiperiodic lattice in two dimensions as well as for a regular lattice.
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  • Keizo Murata, Naoki Toyota, Yoshiaki Honda, Takahiko Sasaki, Madoka To ...
    1988 Volume 57 Issue 5 Pages 1540-1543
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Oscillations in the transverse magnetoresistance of β-(BEDT–TTF)2I3 and β-(BEDT–TTF)2IBr2 were observed below 4.2 K in fields above 9 Tesla applied perpendicular to the a-b plane. The period of the resistance oscillation vs the inverse magnetic field proved that the cross-sectional area of the two-dimensional Fermi surface was nearly a quarter of the first Brillouin zone for both β-(BEDT–TTF)2I3 and β-(BEDT–TTF)2IBr2. Beat-like phenomenon in the magnetoresistance oscillation was also observed in both salts, and its origin is discussed. The fact that the two salts are quite similar in Shubnikov-de Haas effect suggests that the difference in the band structure in the low- and high-Tc states of β-(BEDT–TTF)2I3 is small.
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  • Kazuo Hida
    1988 Volume 57 Issue 5 Pages 1544-1547
    Published: May 15, 1988
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    A model of the high-Tc oxide superconductor based on the antiferromagnetic spin wave exchange mechanism is investigated within the mean field theory. It is assumed that the holes which are the superconductive carriers are mainly doped into the O site on the Cu–O plane. Cu spins are assumed to be localized and in an almost antiferromagnetic state. It is shown that the exchange of the antiferromagnetic spin wave between the holes results in the Cooper pairing with d-like symmetry.
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  • Yasukage Oda, Hiroshi Fujita, Toshiyuki Ohmichi, Takao Kohara, Ichiroh ...
    1988 Volume 57 Issue 5 Pages 1548-1550
    Published: May 15, 1988
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    The superconducting transition temperatures and the lattice parameters of Y1Ba2(Cu1−xAlx)3Oy and Y1Ba2(Cu1−xZnx)3Oy compounds were measured. The crystal symmetry was found to transform from the orthorhombic form to the tetragonal in the Al compound when x is increased, while the orthorhombic structure is maintained in the Zn compound.
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  • Tsuyoshi Murao, Hiroshi Nakatani, Hideaki Taniyama
    1988 Volume 57 Issue 5 Pages 1551-1553
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    The role of the valence fluctuation in high-Tc superconductors is investigated from the viewpoint that the frequency of valence fluctuation is slower than the frequency of lattice vibration (the breathing mode) so that the lattice displacement manifests two possible valence states of atoms showing double minima in the atomic potential. This can lead to a large electron-phonon interaction suggesting that the high-Tc superconductors are inherent structural instability superconductors.
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  • Kazushi Kanoda, Takeshi Kawagoe, Masahiko Hasumi, Toshihiro Takahashi, ...
    1988 Volume 57 Issue 5 Pages 1554-1557
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Superconducting fluctuation-induced diamagnetism was observed in YBa2Cu3O7−δ with different oxygen deficiencies. In a slightly deficient sample, the fluctuation is small and exhibits the temperature dependence of a three-dimensional nature. With increasing defects, however, the fluctuations were found to be enhanced and exhibit a crossover from three- to two-dimensional behaviors at higher temperatures. The dimensionality, which is controlled by the interlayer coupling between the CuO2 planes, is very sensitive to oxygen deficiency in the CuO chains, even when the critical temperature remains around 90 K.
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  • Kiyohiro Sugiyama, Takeshi Kanomata, Hideaki Ido, Muneyuki Date
    1988 Volume 57 Issue 5 Pages 1558-1561
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Magnetization process of the intermetallic compound Fe2−xMnxAs is investigated under a high magnetic field up to 560 kOe with a special interest in the metamagnetic behaviors both in the antiferromagnetic and ferrimagnetic states. Two kinds of stepwise transitions are found and the observed field-induced transitions are attributed to the step magnetizations of the site-I moment where two kinds of magnetic instabilities appear under a high magnetic field. The moment increases of Fe and Mn spins of two metamagnetic states are quantitatively determined.
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  • Shigeru Takagi, Tatsuya Kimura, Nobuya Sato, Takeo Satoh, Tadao Kasuya
    1988 Volume 57 Issue 5 Pages 1562-1565
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Specific-heat and Cu NMR measurements have been made on the recently discovered heavy-electron compound CeCu2In. The low-temperature specific heat has an enormous electronic contribution with CelT\simeq1.2 J/mole·K2 below 1.2 K, and shows a broad maximum at around 2.2 K. Below 2.3 K, Cu NMR linewidth ΔH shows appreciable additional broadening, and the nuclear transverse relaxation also becomes appreciably slower. These results indicate that CeCu2In undergoes an antiferromagnetic phase transition at TN\simeq2.3 K. The possibility of ordering of quite a small moment is suggested from the observations of the gigantic value of CelT below TN, the small magnetic entropy at TN, and the steady increase of CelT through TN with decreasing temperature.
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  • Hidetoshi Nishimori, Yasuhiro Tomita
    1988 Volume 57 Issue 5 Pages 1566-1567
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    The ground-state properties of the spin-1/2 RKKY Heisenberg spin glass are investigated on the fcc lattice. Numerical diagonalization of finite-size systems and extrapolation to the infinite system suggest either that the correlation function decays in a power law ⟨S0·Sr2r−1−η (η=0.02±0.09) or that there is a small but finite value of the order parameter. From comparison with other theories, we prefer the former possibility of vanishing spin glass ordering.
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  • Yoh Kohori, Hirofumi Shibai, Yasukage Oda, Yoshio Kitaoka, Takao Kohar ...
    1988 Volume 57 Issue 5 Pages 1568-1571
    Published: May 15, 1988
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    NQR spectra of Cu in both SmBa2Cu3O7−y and GdBa2Cu3O7−y were observed around 20–23 and 30–33 MHz, which are almost in the same range as those observed in YBa2Cu3O7−y. Study of the relaxation process in Sm- and GdBa2Cu3O7−y reveals a large increase in the nuclear relaxation rate, 1⁄T1, for Cu at 32.5 MHz, while a small increase for Cu at 22.5 MHz. The difference in the enhancement of each line, which is governed by rare-earth spin fluctuations, enables us to definitely assign the signals at 32.5 MHz and 22.5 MHz to the planar and chain sites, respectively, based on a quantitative point of view.
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  • Mitsuhiro Nakajima, Kiyoshi Kawamura, Takuro Tsuzuku
    1988 Volume 57 Issue 5 Pages 1572-1576
    Published: May 15, 1988
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    An in situ ESR study has been made on the process of HNO3 intercalation in graphite through gas-phase reactions at room temperature. The absorption lines under a magnetic field parallel and/or perpendicular to the c-axis were single Dysonian throughout the process which continues to a stage-2 structure. The g-value and line width exhibited complicated variations with exposure time, while each curve consisted of two parts distinctly bounded by an apparent discontinuity. Qualitative interpretation is given in relation to the electronic structure changing with intercalation.
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  • Yoshimasa Matsuno
    1988 Volume 57 Issue 5 Pages 1577-1593
    Published: May 15, 1988
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    The interaction process of two algebraic solitons of a model equation for deep water waves is investigated by employing the pole representation of a 2-soliton solution. In this representation, an algebraic soliton can be identified with a complex pole. It is found that the details of the interaction process of two solitons are governed by each amplitude of solitons. The characteristic is in striking contrast to that of the collision of the Benjamin-Ono(BO) algebraic solitons where the interaction process is completely determined by the amplitude ratio of two solitons. Finally, an initial condition evolving into two pure solitons is presented. It has a Lorentzian profile. The ratio of the amplitudes of resultant two solitons is shown to depend on a parameter greater than a certain positive value. This result is quite different from the corresponding BO case where the amplitude ratio takes a constant value.
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  • Akira Nakamura
    1988 Volume 57 Issue 5 Pages 1594-1600
    Published: May 15, 1988
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    We consider the 2+1 dimensional Toda lattice equation, Δ log (1+Vn)−Vn+1+2VnVn−1=0, (Δ≡∂2⁄∂x2+∂2⁄∂y2=∂2⁄∂r2+r−1∂⁄∂r+r−22⁄∂θ2), under the periodic boundary condition Vn=Vn+N with N being arbitrary integer. We have obtained exact solutions with finite period N. When the period N is infinity (N=∞), the present solution coincides with the previously known cylindrical soliton of Toda equation. When the period N is finite, the present solution represents the cylindrical soliton-like wave but deformed from pure cylindrical symmetry.
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  • Kenn Kubo, Kazuo Saitoh, Satoshi Takada
    1988 Volume 57 Issue 5 Pages 1601-1609
    Published: May 15, 1988
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    Using the quantum transfer-matrix method we have calculated the spin correlation functions of the S=3⁄2 XXZ chain and examined the temperature dependence of the mass (≡ the inverse of the correlation length), susceptibility χx(Q) and the magnetic structure factor Sz(Q). The result shows that the mass vanishes at T=0 for the planar and isotropic cases (−1≤Δ≤1) in agreement with the theoretical prediction. At a low temperature the peak of Sz(Q) at Q=π has been observed to persist even in the ferromagnetic region (0<Δ<0.8). The susceptibility χz(Q=0) at T=0 has been obtained with use of the extrapolation. The critical indices have been also examined.
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  • Kiyomi Okamoto, Tadao Sugiyama
    1988 Volume 57 Issue 5 Pages 1610-1620
    Published: May 15, 1988
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    The ground state properties of the one-dimensional spin-1/2 alternating Heisenberg-XY ferromagnet are analytically investigated by the use of the phase Hamiltonian representation. To treat the non-harmonic terms in the phase Hamiltonian, both the self-consistent harmonic approximation (SCHA) and the renormalization group method are applied. The ground state is either the effective singlet (ES) state or the so-called spin-fluid state. The phase diagram is depicted on the Δ−δ plane, where Δ and δ are the anisotropy and alternation parameters, respectively. The longitudinal and transverse spin correlation functions (⟨SizSjz⟩ and ⟨Si+Sj⟩) in the ES state are also discussed in the framework of the SCHA.
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  • Katsumi Yonei
    1988 Volume 57 Issue 5 Pages 1621-1630
    Published: May 15, 1988
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    Using an effective potential determined from the temperature-dependent Thomas-Fermi-Dirac-Weizsäcker theory with a correlation correction, the bound state one-electron energies of atoms embedded in a neutral medium are calculated. In evaluating the energy eigenvalues, use is made of the WKB approximation. As an example to illustrate the temperature and the compression effects on the one-electron energies, the calculated results for Fe at temperatures ranging from 0 to 1000 eV under fixed compressions ρ⁄ρ0=1, 10 and 100 are presented. The results are in good agreement with available data from SCF methods.
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  • Atsushi Ichimura, Takahiro Tsutsumi
    1988 Volume 57 Issue 5 Pages 1631-1640
    Published: May 15, 1988
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    We investigate the excitation of a hydrogen-like ion from 1s state to 2s by simultaneous two-electron impact at subthreshold incident energies, as an example of three-body scattering, in which three particles enter and three emerge. The excitation rate is roughly estimated with the second-order Born approximation in terms of the long-range dipole interaction between an electron and an ion. In most cases, the rate for the ion is found to have the order of magnitude of \lesssim10−25n2Z8 sec−1, where n denotes the electron number density (in cm−3) and Z, the nuclear charge of the ion. Those values may be too small to be detectable in ordinary beam experiment, though they are found to be comparable to the geometrical cross section introduced for three-body collision. We also discuss the effects of the double-scattering singularity of the transition amplitude.
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  • Yoshifumi Kimura
    1988 Volume 57 Issue 5 Pages 1641-1649
    Published: May 15, 1988
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    Motion of point vortices in a circular domain is studied. Especially the case of two vortices with equal strength is presented. The motion is described by a Hamiltonian as well as when they are in an infinite region. Though the system is integrable in the sense of Liouville, there is a wide variety of motion according to initial conditions. Classification of the motion can be made by considering two integrals and two parameters.
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  • Hyung-Jong Ko, Moon-Uhn Kim
    1988 Volume 57 Issue 5 Pages 1650-1661
    Published: May 15, 1988
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    Electrohydrodynamic convective instability in a horizontal fluid layer with temperature gradient is studied. For smaller electric forces, convection is set in as a static mode. As the electric force becomes larger, convection occurs as a time-periodic motion. Transition point from a static mode to an overstable mode is determined by the Prandtl number. Nonlinear evolution of disturbances near the onset of convection is also considered. Special attention is paid to ranges of parameters falling in the neighborhood of the multiple bifurcation point. For a certain range of the Prandtl numbers, the hysteresis between static and overstable modes can appear. Subcritical instabilities are also possible for small or high enough values of the Prandtl number.
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  • Osamu Sano
    1988 Volume 57 Issue 5 Pages 1662-1668
    Published: May 15, 1988
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    A theoretical study is made on the steady thermal convection of a viscous fluid confined in a vertically oriented thin toroidal loop which is placed in vertically uniform temperature gradient. The Boussinesq approximation is employed, and first-order perturbed fields from steady heat conduction state are examined. Particular attention is paid to the effect of asymmetry on the three-dimensional flow with four cells, which exists at 12.890 times the critical Rayleigh number for the onset of convective flow. The expressions of the helical bi-directional flows are also given. These flows are compared with those observed recently in our experiment.
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  • Tetsumori Yuyama
    1988 Volume 57 Issue 5 Pages 1669-1675
    Published: May 15, 1988
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    The behavior of hot electrons was investigated by feeding a high power microwave with a frequency of 28GHz in the NBT–1M device. A deficit of high energy tail (≥2 MeV) was observed in the measured pulse-height spectra corresponding to X-ray spectra. It is shown that the deficit is brought forth by a shift of the electron cyclotron resonance region due to the relativistic effect. By using the reasonable distribution function for the hot electrons, the density and the averaged kinetic energy of the electrons are determined.
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  • Masaki Nakamura, Yoshiko Fujii, Toyoichir\={o} Shigi, Keisuke Nagao
    1988 Volume 57 Issue 5 Pages 1676-1680
    Published: May 15, 1988
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    The phase separation curve of dilute solution of 4He in liquid 3He has been studied using a sensitive dielectric technique and a film-flow-tight valve attached to a cell. The solubility of 4He at low temperatures was larger than the value expected from the equation proposed by Saam et al.
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  • Makio Uwaha
    1988 Volume 57 Issue 5 Pages 1681-1686
    Published: May 15, 1988
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    Shape relaxation of a crystal faces and of vicinal faces is theoretically studied in terms of step movement. When a flat vicinal surface is perturbed, the power of wave number dependence in the relaxation time τ is determined by the bottleneck process, step movement or diffusion, and the proportionality constant depends on the relative angle of the wave vector and the steps. If a small crystal is quenched through a roughening transition, a new equilibrium shape with a facet emerges when the step loops shrink or expand. If diffusion is fast, Ds→∞, gradual flattening occurs with τ∝Rc2 (Rc: radius of the 2D critical nucleus). If the step mobility is large, ηs→∞ and the transport relies on slow diffusion, a small facet appears on the top of the crystal and the facet size expands as Rft1⁄5.
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  • Biao Jin, Yoshihiro Kuroda
    1988 Volume 57 Issue 5 Pages 1687-1698
    Published: May 15, 1988
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    We study critically the properties of the infinite-U degenerate impurity Anderson model and lattice Anderson model using the bosonic technique with the help of the Feynman diagrammatic expansion developed earlier by P. Coleman. We investigate their thermal and/or dynamical properties over the whole temperature range employing the expansion in power of the inverse of the spin-orbit degeneracy. In the impurity model, the most and the next dominant terms in the expansion turn out to describe the low and the high temperature behaviors correctly. As regards the lattice model we calculate the life time of the conduction electrons and find that all the terms to the third dominant order must be taken into account to describe both of the Fermi-liquid behavior at low temperature and the Kondo-impurity-type behavior at high temperature correctly.
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  • Kazuo Soda, Tamiko Mori, Yoshichika \={O}nuki, Takemi Komatsubara, Tak ...
    1988 Volume 57 Issue 5 Pages 1699-1706
    Published: May 15, 1988
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    Energy distribution curves of valence-band photoelectrons in CeCu2Si2 excited with photons at low energies coincide well with the energy-band density of states curve. The 4f partial energy distribution curve estimated as the difference between the on- and off-resonance spectra in the 4d-4f resonant photoemission has a broad profile extending up to 8 eV with three weak features at 0.4, 1.5 and 2.5 eV and does not resemble the 4f partial density of states curve given by the energy band calculation. The overall shape of the 4f partial energy distribution curve in the major part below 4 eV is similar to a 4f spectrum calculated by Gunnarsson-Schönhammer on the basis of the Anderson model.
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  • Atsushi Suzuki, Tomohisa Yamashita, Kentaro Matsui, Masao Doyama
    1988 Volume 57 Issue 5 Pages 1707-1716
    Published: May 15, 1988
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    The commensurate-incommensurate (C–I) charge-density wave (CDW) phase transition of the system 1T-TaS2−xSex (0≤x≤2) was studied by measuring the heat capacity and the lattice constants. From changes in the heat capacity, the intermediate phases similar to those of 1T-TaS2 are detected only for x≤0.85, while they are not observed for 0.90≤x as in 1T-TaSe2. The lattice constants of the C–CDW phases exhibit two step-like changes around x=0.7 and 1.4. From both results, stability of the intermediate phases and the role of anion ordering are discussed. It is predicted that the C–CDW phase in 0.1≤x≤0.6 is strongly suppressed under pressure.
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  • Arisato Kawabata
    1988 Volume 57 Issue 5 Pages 1717-1723
    Published: May 15, 1988
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    Anderson localization in two-dimensional electron systems with spin-orbit coupling is discussed within the frame work of renormalization group theory. The metal-insulator transition is predicted by taking into account of the renormalization of the spin-relaxation time, which has been overlooked so far.
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  • Naoki Toyota, Kazuaki Fukamichi, Akihisa Inoue, Kunio Matsuzaki, Tsuyo ...
    1988 Volume 57 Issue 5 Pages 1724-1728
    Published: May 15, 1988
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    Temperature and magnetic field dependences of the electrical resistance R(T, H) of a quasi-crystalline (QC) Al-22.5 at%Mn and its counterpart amorphous (AM) alloys have been studied. Little difference in R(T, H) between these two phases is observed accompanying the following common characteristics. The resistance in the absence of magnetic field has a −log T dependence which holds down to near the spin-glass freezing temperature Tf (8.5 K for QC, 7.4 K and 10 K for AM: Al-22.4 and -24.3 at%Mn, respectively). Below Tf, R(T) deviates downward from the −log T curve. A negative magnetoresistance is observed at low temperatures below 10 K and monotonically enhanced on cooling. These behaviors may be understood in terms of the Kondo effect in a spin-glass state.
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  • P. Lederer
    1988 Volume 57 Issue 5 Pages 1729-1742
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    This paper compares the kinetic energy of holes in the antiferromagnetic (AF) state and in an approximate singlet liquid wave function of the Resonating Valence Bond type (RVB), with only nearest neighbour singlet pairing. The atomic interaction U of the Hubbard model is taken to be large compared with the band width 8t. In the limit 8tU→0, I find that the hole kinetic energy is at most as low in RVB than in AF, but there are indications that it is in fact lower in AF. At finite tU, the comparison between AF and RVB depends on corrections of order tU which are not known yet for RVB, but which should be of the same order as in AF. As a result within the simplest Hubbard model with nearest neighbour hopping, it is unlikely that a small concentration of holes can stabilize RVB if the latter is less stable than AH at half band filling.
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  • Tetsuya Satoh, Y\={u}ichi Tazuke, Tomonao Miyadai, Kensuke Hoshi
    1988 Volume 57 Issue 5 Pages 1743-1750
    Published: May 15, 1988
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    Magnetic measurements are made on a random ferromagnet FexTiS2 (0.36≤x≤0.43). Analysis of the magnetization curve for x=0.38 and 0.42 shows that both compounds show the behavior characteristic of an Ising ferromagnet down to 4.2 K. No sign of reentrant spin glass phase is observed in the magnetization data. Time decay of the isothermal remanent magnetization MIR(t) is measured for x=0.37 and 0.38. The MIR vs t curve changes from one type to another at ∼29 K for x=0.37 and at ∼21 K for x=0.38. These temperatures are tentatively assigned as the reentrant spin glass transition temperatures. Combined with our previous study, the temperature vs concentration phase diagram is determined.
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  • Tsuneaki Goto, Toshiro Sakakibara, Kazuaki Fukamichi
    1988 Volume 57 Issue 5 Pages 1751-1757
    Published: May 15, 1988
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    Magnetic susceptibility and high field magnetization up to 300 kOe are measured on Al–Mn quasicrystalline and amorphous alloys. The average local moment per Mn, ⟨Pc⟩, and the paramagnetic Curie temperature, θp, are determined from the temperature dependence of susceptibility. The magnitude of saturation magnetization per Mn, Ms, is much smaller than that of ⟨Pc⟩, suggesting Mn sites are partly magnetic. The atomic fraction Xm and the average local moment, Pc, of the magnetic Mn are estimated from the values of Ms and the Curie constant. All the values of Xm, Pc and |θp| increase monotonically with increasing Mn content in the quasicrystalline and amorphous phases. The magnetic properties of the quasicrystals are similar to those of the amorphous alloys, but slight differences are observed in the high field magnetization process and the values of Xm, Pc and θp.
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  • Yoshinori Muraoka, Toshihiro Idogaki, Norikiyo Uryû
    1988 Volume 57 Issue 5 Pages 1758-1761
    Published: May 15, 1988
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    The paramagnetic susceptibility of FeTa2O6 is analyzed by the method of high-temperature series expansion based on a two-dimensional Heisenberg model with single-ion anisotropy. Both the nearest and next-nearest neighbor exchange interactions are taken into consideration and estimated in a compatible form with the spin structure.
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  • Kiyohiro Sugiyama, Yukio Koyoshi, Satoru Kunii, Tadao Kasuya, Muneyuki ...
    1988 Volume 57 Issue 5 Pages 1762-1770
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    High field magnetization of GdB6 is investigated up to 550 kOe. The saturation magnetization of 7±0.5 μB is obtained around 490 kOe at 1.3 K and the system can be regarded as a typical cubic antiferromagnet with the nearest neighbor exchange energy J0k of −0.78±0.02 K. Beside the standard antiferromagnetic magnetization, two small anomalous step-magnetizations are found near the saturation field Hc. They are explained by the local spin flip of the disordered Gd located at the B6 cluster site. Two kinds of the disordered states, Type-I and Type-II, are proposed corresponding to two steps. The disordered Gd spin couples with the surrounding host spins with the antiferromagnetic exchange energy J′⁄k of −1.2 K and −1.3 K for Type-I and Type-II, respectively.
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  • Takashi Imai, Tadashi Shimizu, Toshinobu Tsuda, Hiroshi Yasuoka, Toshi ...
    1988 Volume 57 Issue 5 Pages 1771-1779
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Nuclear spin-lattice relaxation times T1 of 63Cu and 65Cu in the Cu(2) sites of the high Tc superconductor YBa2Cu3O7−δ (δ\simeq0.1, Tc=91 K) have been measured for the wide temperature range between 2.2 K and 300 K. The temperature dependence of 1⁄T1 in the normal state has been found to be the one unexpected for simple metals. The influences of antiferromagnetic spin fluctuations in the d-p bands in the Cu(2)–O layers are discussed. The temperature dependence of 1⁄T1 below Tc has also been found to be the one which is not expected for isotropic BCS superconductors. The power-law like temperature dependence of 1⁄T1 without any enhancement just below Tc has been observed between 40 K and 91 K.
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  • Masahiro Shirasaki, Shinobu Takahashi, Hajime Kudo, Akio Yamada, Masaa ...
    1988 Volume 57 Issue 5 Pages 1780-1788
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Measurements were made to obtain piezoreflectivity spectra of Rb+ core excitons in RbBr under a stress along the [011] direction at room temperature. From the dichroism of the spectra, trigonal deformation potentials of structures located at 16.1, 16.5, 17.0, 17.4 and 18.2 eV are determined to be −0.17, −0.48, −0.57, −0.09 and 0.34 eV, respectively. Those deformation potentials are in good agreement with values calculated from the localized excitation model for the core excitons proposed by Satoko and Sugano. It is concluded, therefore, that the excitons located at 16.1 and 18.2 eV are mainly of the (4p)5(5s) and (4p)5(4dγ) characters, respectively, and that the localized excitation model is useful in the analysis of the core excitons.
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  • Susumu Kurita, Mikako Haruki, Kensuke Miyagawa
    1988 Volume 57 Issue 5 Pages 1789-1796
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Photo-induced absorption effects have been investigated in [Pt(en)2][Pt(en)2Cl2] (ClO4)4 single crystals. When the crystals are irradiated at 77 K by the light within the charge-transfer absorption band (CT band) or higher, two absorption bands (A and B) are observed below the CT band. Their intensities increase linearly with the total excitation light flux at low excitation level. The photo-induced absorption bands are stable at 77 K, but are not observed at room temperature. The A and B bands are induced only by the light with E// chain and preferencially polarized for E// chain, suggesting that the photo-induced defect states are located on individual chains, and not associated with interchain defects. The results are discussed in terms of the photo-induced polaron and kink-soliton models.
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  • Fumiko Yonezawa, Fumitoshi Sato
    1988 Volume 57 Issue 5 Pages 1797-1813
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    With a view to studying the properties of the optical-absorption edge in a–Si, we calculate in the CPA the density of states (DOS), the absorption spectra and the spectral density on the basis of the site-disordered Abe-Toyozawa model. As the probability distribution for site disorder, we use the bilateral exponential distribution and the distribution defined by an exponential factor with the fourth-order power in its argument as well as the common Gaussian distribution. Our assertion is that, to make the model realistic, we must choose the degree of disorder small enough relative to the band width such that we can identify the three regions of absorption with high, intermediate and low energies. The intermediate region in this case universally shows an exponential behaviour, irrespective of the type of the probability distribution of “static” disorder. We compare the absorption spectra I(E) calculated from the Kubo formula with the convolution Iconv(E) in which the k-selection rule is completely relaxed. We clarify the conditions under which Iconv(E) serves as a good approximation of I(E).
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  • Etsuo Kawate, Taizo Masumi
    1988 Volume 57 Issue 5 Pages 1814-1819
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Luminescence spectra of pure AgBr have been investigated in the vicinity of the indirect band gap at the temperature region between 500 mK and 50 K by using 3He-coolant under various excitation conditions. Systematic studies of the effects of annealing on luminescence spectra of free excitons in AgBr have revealed that the lifetime of free excitons in a specimen after annealing can be extremely prolonged and the excitonic temperature in the specimen can be further lowered than that in a specimen before annealing. Luminescence spectra for an annealed specimen under a uniaxial stress at low temperatures have also been studied to ensure an understanding of the cause of these two phenomena.
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  • Etsuo Kawate, Taizo Masumi
    1988 Volume 57 Issue 5 Pages 1820-1825
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Dynamical behaviour of free excitons in AgBr has been studied by observing the space-resolved luminescence spectra. Experiments on the spatial distribution of the free excitons have been carried out, for the first time, in pure and well-annealed AgBr crystals between 1.7 and 20 K. Observed distributions are consistent with a diffusion model due to a gradient in density of free excitons. By analysing the distributions, we can well explain the momentum relaxation rate of free excitons in terms of the scattering of the free exciton by longitudinal acoustic phonons.
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  • Etsuo Kawate, Taizo Masumi
    1988 Volume 57 Issue 5 Pages 1826-1833
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Dynamics of the relaxation of free excitons in pure and well-annealed specimens of AgBr have been investigated by observing time-resolved luminescence spectra at the temperature region between 500 mK and 18 K. Experimental results at high temperature region reveal the energy relaxation mechanism which can be explained in terms of the combination of exciton-LA phonon interaction and exciton-exciton collision. With decreasing temperature, the deviation from these situations becomes remarkably evident. This fact, together with a fine structure in the spectra, suggests that polaron effects are substantial in the system of free excitons.
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  • Masataka Hasegawa, Kenji Kimura, Michi-hiko Mannami
    1988 Volume 57 Issue 5 Pages 1834-1841
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    Convoy electrons emitted at glancing angle incidence of MeV protons and He+ ions on a clean (001) surface of SnTe are observed. It is found that the most probable velocities of convoy electrons are slower than those of the ions at proton incidence, whereas they are faster at He+ incidence. A qualitative model is proposed to explain the experimental observations, in which the acceleration of convoy electrons by the wake-like induced charge on the solid surface at glancing angle incidence of swift ions is taken into account.
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  • Etsuro Ito, Hiroto Kikuchi, Hideo Suzuki
    1988 Volume 57 Issue 5 Pages 1842-1851
    Published: May 15, 1988
    Released on J-STAGE: June 01, 2007
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    We consider the ground state (GS), the excited state on absorption (ESA), the virtual ground (VGS) and the deformed excited state (DES) of π-electron system in hexaene, retinal, retinal Schiff-base (RSB), protonated retinal Schiff-base (PRSB) or our model for rhodopsin chromophore, and we semiempirically calculate the following two kinds of force constants for the pairs of bonded atoms in each of the four π-electronic states: (1) the force constants of torsional vibrations; (2) those of the interactions between torsional and stretching vibrations. The calculations are carried out by our LCAO–ASMO–SCF–CI method for π-electrons, selecting such a part of the total energy of π-electron system that gives a significant contribution to the force constants.
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  • Hiroshi Orihara, Yoshihiro Ishibashi
    1988 Volume 57 Issue 5 Pages 1852-1854
    Published: May 15, 1988
    Released on J-STAGE: May 29, 2007
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    Poly-nuclear growth transient in one-dimensional systems was simulated under a periodic boundary condition. It has turned out that the growth rate attains the stationary value predicted by theories at quite an early stage. The results are discussed in the relationship with analytical models.
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