Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 66, Issue 7
Displaying 1-50 of 60 articles from this issue
  • Umesh Chandra Pandey, S. Dev
    Subject area: Specific theories and interaction models; particle systematics.
    1997 Volume 66 Issue 7 Pages 1853-1855
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Majorana neutrino transition magnetic moments [MNTM] in a superstring inspired E6 model are investigated. The additional fermions in the 27-plet of E6 are shown to lead to a large enough MNTM for a reasonable choice of Yukawa couplings without imposing the additional `exotic' symmetries prevalent in most other models for large neutrino magnetic moments.
    Download PDF (285K)
  • Kenji Nomura, Naohiko Yasuda, Hidehiro Ohwa, Hikaru Terauchi
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 7 Pages 1856-1859
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Ordered (S=0.8) and disordered (S=0) crystals of PbIn1/2Nb1/2O3 (PIN) were investigated by X-ray diffraction measurement in the temperature range of 20, K to 580, K. The (h/4 k/4 0) superlattice reflection for the ordered antiferroelectric sample and the (h h h) fundamental reflection for the disordered ferroelectric sample were measured for evaluation of the temperature dependence of their order parameters. The (h/2 k/2 0) (α -spots) and the (h/2 0 0) (β -spots) superlattice reflections were also observed. The temperature dependence of the integrated intensity of the α -spot was compared with that of the (h/4 k/4 0) reflection in both samples. Their reflections showed the same temperature dependence. The origin of the α -spots is due to the antiferroelectric distortion. The temperature dependence of the integrated intensity of the α -spot of the ordered sample was different from that of the disordered sample. The differences were explained by a size effect of the clusters.
    Download PDF (341K)
  • Hiroshi Abe, Ryuji J. Matsuo, Mikio Ishibashi, Ken–ichi Ohshima, ...
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 7 Pages 1860-1863
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    In metallic sodium, a characteristic waiting time, which is the incubation time until phase transition starts, appears above Ms at a fixed temperature. Small-angle neutron scattering from clusters of the low-temperature phase is observed, which shows good agreement with the aggregation-of-spheres model, whose radius distribution is a Maxwell distribution function. Using the aggregation-of-spheres model, the average radius, r0, of clusters of the low-temperature phase was found to be 57.2, Å. Moreover, abnormal small-angle neutron scattering from local fluctuations is seen during the waiting time, where this waiting time is related to the nucleation process in the martensitic phase transition.
    Download PDF (397K)
  • Mitsutaka Fujita, Masatsura Igami, Kyoko Nakada
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 1864-1867
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We study the lattice distortion in graphite ribbons of a nanometer width by taking account of the electron-phonon interaction in the tight binding model. In the ribbons with armchair edges, the typical Kekulé structure appears near the edges depending on the distribution of the bond orders. On the other hand, the zigzag ribbons do not undergo bond alternations along the ribbon axis, implying less Peierls instability. Special emphasis is put on the survival of the edge state which forms almost flat bands and a sharp peak in the density of states in consideration of the electron-phonon interaction.
    Download PDF (438K)
  • Satoru Nakatsuji, Shin–ichi Ikeda, Yoshiteru Maeno
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 1868-1871
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Noncuprate layered perovskite Sr2RuO4 is a highly correlated metal and exhibits superconductivity below Tc≈ 1.35, K. We have newly synthesized related layered ruthenates Ca2RuO4 in two distinct structural phases with substantially different aspect ratios c/a. Electrical and magnetic measurements show that the two phases are insulating antiferromagnets. We argue that both phases of Ca2RuO4 are Mott insulators. The decrease of the 4d band width in comparison with that of Sr2RuO4, caused by distortions in the RuO2 planes, leads to a Mott-Hubbard-type gap.
    Download PDF (385K)
  • Yukitoshi Motome, Masatoshi Imada
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 1872-1875
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We present a framework of an auxiliary field quantum Monte Carlo (QMC) method for multi-orbital Hubbard models. Our formulation can be applied to a Hamiltonian which includes terms for on-site Coulomb interaction for both intra- and inter-orbitals, intra-site exchange interaction and energy differences between orbitals. Based on our framework, we point out possible ways to investigate various phase transitions such as metal-insulator, magnetic and orbital order-disorder transitions without the minus sign problem. As an application, a two-band model is investigated by the projection QMC method and the ground state properties of this model are presented.
    Download PDF (357K)
  • Hirokazu Tsunetsugu, Masatoshi Imada
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 7 Pages 1876-1879
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The conductivity and Hall coefficient for various types of t-J ladders are calculated as a function of temperature and frequency by numerical diagonalization. A crossover from incoherent to coherent charge dynamics is found at a temperature Tcoh. There exists another crossover at TPG below which a pseudogap opens in the optical spectra, induced by the opening of a spin gap. In the absence of the spin gap, Tcoh and the coherent weight are suppressed especially with increasing dimensionality. On the contrary, Tcoh is strongly enhanced by the pseudogap formation below TPG, whereas the coherent Drude weight decreases with increasing dimensionality. The Hall coefficient shows a strong crossover at TPG below which it has large amplitude for small doping concentration.
    Download PDF (399K)
  • Guo–qing Zheng, Hayato Wakabayashi, Yoshio Kitaoka, Kunisuke Asa ...
    Subject area: Superconductivity.
    1997 Volume 66 Issue 7 Pages 1880-1883
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The 63Cu spin-lattice relaxation rate has been measured in an annealed sample of Tl2Ba2Ca2Cu3O10 with Tc=123 K, and compared with that in the previously reported as-grown sample with Tc= 115 K. We found, for the first time, that Tc increases as a result of a decrease in the residual density of states (DOS), Nres, at the Fermi level due to the improvement of crystal ordering by {annealing}. Based on the T1 result, Nres normalized by the value at Tc, Nres/N0, was found to be reduced from 0.30 to 0.18 after annealing. A 2-dimensional d-wave superconductivity model accounts for the increase of Tc in terms of the change in potential scattering due to crystal imperfection, which is probably caused by Ca/Tl inter-substitution.
    Download PDF (281K)
  • Noriaki Sato, Naofumi Aso, Gerry H. Lander, Bertrand Roessli, Takemi K ...
    Subject area: Superconductivity.
    1997 Volume 66 Issue 7 Pages 1884-1887
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We have found that there are two contributions to the dynamical response in UPd2Al3. The first is a heavily damped spin-wave, which has been observed previously. It shows no appreciable change on warming through Tc, but softens and becomes overdamped as T approaches TN. The second is a quasielastic-like component that exists in the antiferromagnetically ordered state and is strongly localized around the ordered wavevector. As a function of temperature this component exhibits a minimum at the superconducting transition temperature Tc, and increases strongly below Tc. Its width in the momentum space at T = 0.5, K corresponds to a correlation length of -- 50, Å, which is close to the superconducting coherence length of -- 85, Å.
    Download PDF (473K)
  • Minoru Nohara, Masanobu Isshiki, Hidenori Takagi, Robert J. Cava
    Subject area: Superconductivity.
    1997 Volume 66 Issue 7 Pages 1888-1891
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The low temperature specific heat of the borocarbide superconductor LuNi2B2C was measured under various magnetic fields (H) up to 8 T. The coefficient of the T-linear term in specific heat in the mixed state shows marked deviations from the H-linear dependence expected for conventional superconductors and is found to obey a √{H} dependence. A good description of the data can be obtained by assuming the presence of a zero-gap region along lines on the Fermi surface, indicating the possibility of unconventional pairing in the superconducting state of the borocarbides.
    Download PDF (392K)
  • Tatsuya Kawae, Masakazu Ito, Masaki Mito, Masako Hitaka, Kazuyoshi Tak ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1892-1895
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We have carried out magnetic susceptibility and heat capacity measurements on a typical Haldane antiferromagnet (CH_3)_4Nni(NO)_3 (TMNIN) doped with nonmagnetic Zn2+ ion impurities at the concentrations of 7.4%, 11.8% and 20.4% and on a pure system down to 0.2 K. At low temperatures below 1.2 K, the paramagnetic susceptibility expected in the Haldane system with the open chain is found to be suppressed. A broad maximum of the heat capacity is observed around 0.7 K for each impurity system. The observed results strongly suggest that there exists an antiferromagnetic interaction between the edge S=1/2 spins adjacent to Zn2+ ions via the next-nearest exchange interaction Jnn which can be regarded as a bond impurity in the Haldane system. This is the first experiment on bond impurity models for the Haldane system.
    Download PDF (375K)
  • Hiroyuki Ohsumi, Keisuke Tajima, Nobuyoshi Wakabayashi, Yoshio Shinoda ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1896-1899
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    An X-ray diffraction study has been made on holmium metal in a magnetic field at several temperatures. In most cases, the c-lattice parameter has been observed to change discontinuously with increasing magnetic field, corresponding to the appearance of various magnetic structures. The result of numerical calculations by a self-consistent mean field method suggests that the effect of the helifan structure on the crystal lattice has been observed in a narrow range of magnetic field.
    Download PDF (291K)
  • Wakako Shiramura, Ken–ichi Takatsu, Hidekazu Tanaka, Kenji Kamis ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1900-1903
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    High-field magnetization processes of S=1/2 double spin chain systems KCuCl3 and TlCuCl3 have been measured up to 39, T at 4.2 and 1.7, K for both systems and at 1.0 and 0.5, K for TlCuCl3 using single crystals. A transition from a singlet ground state with an excitation gap to a gapless magnetic state with finite susceptibility occurs at Hc-- 20, T and 6, T for KCuCl3 and TlCuCl3, respectively. The critical field Hc depends on the external field direction due to the anisotropy of the g-factor. The excitation gap Δ is evaluated as Δ/kB=31.1, K for KCuCl3 and 7.5, K for TlCuCl3. Although the antiferromagnetic interactions in TlCuCl3 are stronger than those in KCuCl3, which can be seen from the slope of the magnetization curves above Hc, the excitation gap in TlCuCl3 is about a quarter of that of KCuCl3. It is observed that the transition field Hc increases with increasing temperature.
    Download PDF (365K)
  • Fuminori Honda, Tomoko Kagayama, Gendo Oomi, Alexabder V. Andrssv, Lad ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1904-1907
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Thermal expansion and magnetostriction of UNiGa single crystal have been measured at the range of pressures up to 2.2, GPa and magnetic fields up to 1.5, T. The results are reported with a special emphasis on anomalies accompanying the magnetic phase transitions and the effect of pressure on the critical parameters (transition temperature and magnetic field). Formation of a new antiferromagnetic phase induced by pressures above 1.8, GPa is revealed. Analysis of results enabled us to construct P-T magnetic phase diagrams for fields up to 1.5, T. The magnetoelastic effects are discussed in terms of marked variations in electronic structure accompanying transitions between different magnetic structures with various couplings of U magnetic moments along the c-axis and involvement of strong spin-orbit interaction.
    Download PDF (322K)
  • Hirotaka Manaka, Isao Yamada
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1908-1911
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We report that antiferromagnetic and antiferromagnetic (AF-AF) alternating Heisenberg chains with S=1/2 are formed in (CH3)2CHNH3CuBr3, which is in contrast to the almost isomorphous compound (CH3)2CHNH3CuCl3, because the Cl compound forms ferromagnetic-dominant ferromagnetic and antiferromagnetic (F-AF) alternating Heisenberg chains [H. Manaka et al.: J. Phys. Soc. Jpn. 66 (1997) 564]. From the analysis of the dependence of magnetic susceptibility on temperature, χ(T), the two different antiferromagnetic exchange interactions defined in the Hamiltonian {\cal H}= -2J1∑ S2i·S2i+1 -2J2∑S2i·S2i-1 are determined to be J1/k=-61 K and J2/k=-33 K. Applying the low temperature experimental data to the formula χ(T)∝ T-1/2exp(-Δ/kT), we estimate the energy gap Δ to be 98 K. We discuss why AF-AF and F-AF alternating chains are formed in the Br and the Cl compounds, respectively, in spite of their almost isomorphous crystal structures.
    Download PDF (339K)
  • Weijie Zhang, Jun–ichi Igarashi, Peter Fulde
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 1912-1915
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    By extending White's density-matrix renormalization group (DMRG) techniqueto finite temperatures, we calculate the impurity susceptibility for the following systems: (a) a spin-1/2 impurity coupled to a single site of an antiferromagnetic Heisenberg spin-1/2 chainand (b) an impurity coupled symmetrically to the two spins atthe open ends of the chain. We also perform a Monte Carlo simulationand show that the DMRG adaptation gives reliable results.The calculated impurity susceptibility showsPauli-like behavior at low temperatures in the former casewhile a ln T divergence is found in the latter case, in agreement with predictions based on conformal field theory.
    Download PDF (355K)
  • Vladimir L. Safonov, Qingfan Shi, Michinobu Mino, Hitoshi Yamazaki
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1997 Volume 66 Issue 7 Pages 1916-1919
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We considered the process of parametric excitation of spin waves and magnetoelastic waves in magnetoordered crystals in a microwave resonator. From our analysis it follows that for the k and {- k} wave pair there is a single-mode realization (i.e. the pair can be represented as one oscillator). The theory of parametric resonance of waves constructed in terms of these collective variables provides a new perspective on some old spin-wave experiments and helps explain the recently obtained experimental data.
    Download PDF (269K)
  • Naohiko Yasuda, Hidehiro Ohwa, Jun Oohashi, Kenji Nomura, Hikaru Terau ...
    Subject area: Dielectric properties and materials.
    1997 Volume 66 Issue 7 Pages 1920-1923
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The dielectric properties of Pb(In1/2Nb1/2)O3 (abbreviated as PIN) single crystal were investigated under hydrostatic pressures up to 0.7, GPa. The ordered PIN was confirmed to be antiferroelectric by observation of clear P-E double hysteresis loops below the transition temperature. There is a striking pressure effect in the disordered PIN. The relaxor behavior becomes less notable with increasing pressure and disappears at 0.4, GPa. At pressures above 0.4, GPa, the normal phase transition without dielectric dispersion in the low frequency range takes place and with increasing pressure, the temperature Tm, indicating the maximum of the dielectric constant, ε rm, increases at a rate of 150, K/GPa and the ε rm decreases. Such dielectric phenomena with pressure are similar to those observed in antiferroelectric PbZrO3.
    Download PDF (261K)
  • Masatoshi Takeda, Ryuji Tamura, Yoshiko Sakairi, Kaoru Kimura
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1997 Volume 66 Issue 7 Pages 1924-1927
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Using the modulated photocurrent method to measure physical properties in the high-structural-quality single-phase icosahedral quasicrystalline alloy Al70.5Pd21Re8.5, we observed photocurrent similar to that in semiconductors in quasicrystals. The observed results were in agreement with those obtained by applying our recently developed photoconductivity model used for boron-rich semiconductors in which band-to-band photoexcitation and photoexcitation from a band to localized states followed by thermal excitation to the conduction band are both considered. Our results confirm the existence of a pseudogap at the Fermi energy E_F and the tendency of carriers to localize near E_F.
    Download PDF (334K)
  • Takashi Nagatani
    Subject area: Other areas of research of general interest to physicists.
    1997 Volume 66 Issue 7 Pages 1928-1931
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    A traffic jam induced by slowing down is investigated using the optimal velocity model of the car following models. When cars are decelerated in the presence of hindrances, two kinds of traffic jam occur behind the hindrance: one is an oscillating jam and the other is a homogeneous jam. When the slowing down is small, the oscillating jam occurs. If the slowing down is large, the jam is homogeneous over space and time. The linear stability theory is applied to the traffic jam. The critical line and critical mode of the instability are found. It is shown that the boundary between the oscillating and homogeneous jams is consistent with the critical line of the linear stability. The periods of the oscillating jam are about two times and four times the critical mode estimated by the linear stability theory.
    Download PDF (328K)
  • Kazuhiro Fukushima, Tomoji Yamada
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 7 Pages 1933-1938
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Kink-antikink interaction is numerically studied in a system of a perturbed sine-Gordon equation. We study a system in which a kink and an antikink are localized by placing two impurities between them. The kink and the antikink oscillate chaotically near the impurities by applying the external force. We observe kink-antikink motion with changing the strength of coupling, where the strength of coupling can be changed by changing the distance between two impurities. Time series of the distance between two kinks shows similar characteristics to that in the coupled chaotic oscillator system. An intermittency caused by chaos-chaos interaction is also observed. Power spectrum of this intermittency is a type of 1/f.
    Download PDF (428K)
  • Masato Hisakado
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 7 Pages 1939-1942
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We consider the relation between the discrete coupled nonlinear Schrödinger equation and Toda equation. Introducing complex times we can show the intergability of the discrete coupled nonlinear Schrödinger equation. In the same way we can show the integrability in coupled case of dark and bright equations. Using this method we obtain several integrable equations.
    Download PDF (259K)
  • Masayoshi Tajiri, Yosuke Watanabe
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 7 Pages 1943-1949
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Nonlinear intermitted wave solutions that are recurrent in time are presented to the Boussinesq equation by using the superposition of rational growing modes where the effect of the nonlinearity is taken into account. It is also shown that the breather solution can be constructed by imbricate series of rational growing modes.
    Download PDF (574K)
  • Osamu Tsuchiya, Takashi Yamamoto
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 7 Pages 1950-1953
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The boundary effects in the open Hubbard chain with boundary fields are studied. The boundary string solutions of the Bethe ansatz equations that give rise to a wave functions localized at the boundary and exponentially decreasing away from the boundary are provided. In particular, it is shown that the correct ground state of the model at half-filling contains the boundary 1-strings.
    Download PDF (286K)
  • Yusuke Kato, Takashi Yamamoto, Mitsuhiro Arikawa
    Subject area: Classical and quantum physics: mechanics and fields.
    1997 Volume 66 Issue 7 Pages 1954-1961
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We consider the physical properties of elementary excitations of the Calogero-Sutherland (CS) model with SU(K) internal symmetry. From the results on the thermodynamics of this model, we obtain the charge, spin, and statistics of elementary excitations. Combining this knowledge and the known results on the dynamics in the spinless and SU(2) CS models, we propose the expressions for the dynamical correlation functions of the SU(K) CS model. In the asymptotic region, we confirm the consistency of our results with predictions from conformal field theory.
    Download PDF (648K)
  • Michiko Yamana, Hidetoshi Nishimori, Tadashi Kadowaki, D. Sherrington
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 7 Pages 1962-1975
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We develop a systematic expansion method of physical quantities for the SK model and the finite-dimensional ± J model of spin glasses in non-equilibrium states. The dynamical probability distribution function is derived from the master equation using a high temperature expansion. We calculate the expectation values of physical quantities from the dynamical probability distribution function. The theoretical curves show satisfactory agreement with Monte Carlo simulation results in the appropriate temperature and time regions. A comparison is made with the results of a dynamics theory by Coolen, Laughton and Sherrington.
    Download PDF (902K)
  • Taichiro Fukumori, Kenji Imai, Takeo Hasegawa, Yoshito Akashi
    Subject area: Measurement science, general laboratory techniques, and instrumentation systems.
    1997 Volume 66 Issue 7 Pages 1976-1978
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    A precision method of measuring the lattice spacing difference by a sensitivity of 1 part in 107 is presented. The method uses the Kα doublet from one conventional X-ray tube as two beams with a position sensitive proportional counter in a double-crystal spectrometer. To achieve this sensitivity the device positioning the sample crystal parallel to the monochromator is used. The method is applied to the examination of the lattice spacing variations in silicon crystals containing 0.93 to 1.5× 1018, atoms/cm3 of oxygen contents which are subjected to a two-step (low-high) annealing. The lattice spacing differences obtained for these samples are in the range of 10-7--10-6.
    Download PDF (276K)
  • Norio Saito, Isao H. Suzuki
    Subject area: Atomic spectra and interactions of atoms with photons.
    1997 Volume 66 Issue 7 Pages 1979-1985
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The yield ratios of triply charged ions to doubly charged ions produced from Xe+ with 4d3/2 and 4d5/2 holes, from Kr+ with 3d3/2 and 3d5/2 holes, and from Ar+ with 2p3/2 and 2p1/2 holes have been measured using a coincidence technique between an energy-selected photoelectron and a charge-specified ion. The difference in the ratios of the double to the normal Auger transitions from the 2p3/2 and 2p1/2 hole states in Ar+ and that in the ratios from the 3d5/2 and 3d3/2 hole states in Kr+ are small. However the difference in those from the 4d5/2 and 4d3/2 hole states in Xe+ is significant. This difference probably originates from the fact that the energy of the ground state of Xe3+ is just below that of the 4d5/2 hole state of Xe+, i.e., the difference in the excess energy and the number of available states play a critical role in the transition.
    Download PDF (711K)
  • Takasi Endo, Eitaro Morimoto, Yutaka Hirayoshi, Kouich Toyoshima
    Subject area: Optics.
    1997 Volume 66 Issue 7 Pages 1986-1988
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Photocurrent noise from an LED is measured as a function of the current source impedance. Bandwidth of noise reduction is found to be equal to the inverse of the time constant which is the product of the differential resistance of the LED and a paralelly connected capacitance. The experimental results are described in terms of a simple equivalent circuit.
    Download PDF (185K)
  • Hong–Chen Fu, Ryu Sasaki
    Subject area: Optics.
    1997 Volume 66 Issue 7 Pages 1989-1994
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We introduce the negative binomial states with negative binomial distribution as their photon number distribution. They reduce to the ordinary coherent states and Susskind-Glogower phase states in different limits. The ladder and displacement operator formalisms are found and they are essentially the Perelomov's su(1,1) coherent states via its Holstein-Primakoff realization. These states exhibit strong squeezing effect and they obey the super-Poissonian statistics. We discuss two methods to generate these states.
    Download PDF (490K)
  • Katsuya Ishii, Shizuko Adachi, Sadao Akishita
    Subject area: Fluid dynamics.
    1997 Volume 66 Issue 7 Pages 1995-2001
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The sound pressure level is computed using the Lighthill-Curle theory for the far-field acoustic pressure excited by flow around solid bodies. Time evolution of the flow field is obtained by solving the three-dimensional compressible Navier-Stokes equation with a block pentadiagonal matrix scheme based on the approximate factorization method. The far-field sound pressure level is evaluated from the fluctuation of the pressure on a wing surface. Numerical simulation is done for a NACA-0015 airfoil at the attack angle of 8°in a subsonic flow. The computed results are compared successfully with the experimental data. The surface dipole strength density is estimated to show which regions in space dominantly contribute to prominent peaks in the sound pressure level. We discuss the three-dimensional effect by comparing the results from the three- and two-dimensional computation.
    Download PDF (772K)
  • A. M. El–Hanbaly, A. Elgarayhi
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1997 Volume 66 Issue 7 Pages 2002-2007
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    By means of the Lie group approach the symmetry of Vlasov-Fokker Planck equation (VFPE) with an arbitrary electric field of space and time are found. Mathematical forms are obtained for the electric field permit symmetry. Maxwell's equations are then used to constrain the solution further. Finally, we obtain a complete classification of all possible nontrivial similarity solutions of the VFPE plus Maxwell equations.
    Download PDF (368K)
  • Masanori Takaoka
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1997 Volume 66 Issue 7 Pages 2008-2025
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Anisotropy and vortex structures in turbulence subjected to mean uniform strain are investigated by a direct numerical simulation of the incompressible Navier-Stokes equation. Three types of irrotational homogeneous straining flows are examined as a mean flow: plane strain, axisymmetric contraction and axisymmetric expansion. The imposed mean straining flow produces turbulence energy and does so by preferentially inducing the anisotropy in large length scale. The skewness and the flatness of velocity derivatives are also calculated for the conditionally sampled data classified according to vorticity magnitudes, which reveals the role of vortex structure in their deviations from a Gaussian random field. Anisotropy in each length scale is examined in Fourier space. By using the relation of the one-dimensional lateral and longitudinal energy spectra we find that the field becomes isotropic with smaller length scale, though the large length scale structures inherit anisotropy. Our numerical results suggest a phenomenological model of `hierarchic vortex structure'.
    Download PDF (1497K)
  • Kentaro Yabuki, Kunihiko Watanabe, Tetsuya Sato
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 7 Pages 2026-2032
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    In order to examine the role of the energy input in the formation of an ordered structure in a semi-open system, we have developed a nonlinear simulation model in which the energy input time and the dynamic response time of the system are changeable. For this purpose, a viscous membrane (boundary layer) is placed between a steady convection source and a nonlinear feedback system in which a dissipation-free magnetohydrodynamic plasma and a resistive weakly-ionized plasma are coupled. It is found that the thin viscous membrane acts to be a high-pass filter that can play a role of a fixed boundary for the dc component but a free boundary for the ac component. Because of this character of the membrane, when the ratio of the ac energy input time to the dynamic response time of the system becomes relatively large, the membrane acts to release the fluctuation (ac) energy from the system. Consequently, the positive feedback effect for the fluctuation is weakened and the structure formation is prevented as the ratio exceeds a certain critical value. It is also found that the viscous membrane plays another important role in self-organization, namely, that as the structure formation is highly progressed, the dc energy input rate is autonomously adjusted so as to keep the developed structure in a steady form.
    Download PDF (903K)
  • Yuji Kurimoto, Hideki Zushi, Fumimichi Sano, Katsumi Kondo, Toru Mizuu ...
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 7 Pages 2033-2043
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    In the Heliotron E device, combining a neutral beam injection (NBI) with an electron cyclotron resonance heating (ECRH) system, new physical issues are applied to the investigation of fast ion behavior. Especially, the slowing-down (deceleration and parallel diffusion) and the loss processes are studied experimentally through measurements of the temporal change of charge-exchange neutral particle energy spectra. As results, first, in the longer slowing-down time (τs -- 200 ms) plasma realized by ECRH, discrepancies from the theoretical values are detected in the deceleration and the parallel diffusion processes, whose factors are 4--6 for the former, 6--13 for the latter. Second, the fast ion loss cone is reduced by the ECRH on the NBI plasma, of which cause is discussed associated with the modification of the radial electric field, Er.
    Download PDF (1038K)
  • Shinji Nakazawa, Yukiharu Ohsawa
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 7 Pages 2044-2050
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The structure of nonlinear magnetosonic waves with relativistic propagation speeds is studied through theory and particle simulation. First, the maximum values of magnetic and transverse electric fields and electric potential are analytically obtained as a function of the Alfvén speed and Mach number, under the assumption that waves propagate nearly steadily in the direction perpendicular to a magnetic field. Then, one-dimensional, relativistic, electromagnetic particle code with full ion and electron dynamics is used to study relativistic magnetosonic waves. It is found that the ion currents parallel to the the wave front become comparable to the electron currents in magnitude. As the propagation speed is increased, transverse fields become dominant components in electromagnetic fields of a wave. The theoretically obtained values of field quantities are in good agreement with the simulation results.
    Download PDF (553K)
  • Ryoichi Minai, Isao Katanuma, Teruo Tamano
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 7 Pages 2051-2056
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We investigate the ion axial confinement time and the ion endloss spectrum in a wide range of collision frequency in a tandem mirror by using Monte-Carlo simulation. It is found that the ion endloss spectrum and the effective temperature determined from the spectrum have a transition depending on the collision frequency. Particularly, in cases where the collision frequency is low, the effective temperature deviate from the field temperature.
    Download PDF (445K)
  • Mitsuaki Ginoza, Makoto Yasutomi
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 7 Pages 2057-2062
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The solvent-mediated force between colloidal particles in a liquid is studied with the use of the model system consisting of the solvent spheres and the solute spheres (colloidal particles): spheres interact through Yukawa-type potentials with different damping factors. The study is based on the mean spherical approximation solution of the Ornstein-Zernike equation with the closure of three Yukawa terms. In the case of the lyophobic solute in the dilute limit, the dependence of the solvent-mediated force on the interaction between solvent spheres is investigated in relation to the exponential decay nature of the force measured in the range shorter than about 15 nm. The result is consistent with the experimental one.
    Download PDF (451K)
  • Makoto Fuchigami, Kazuyuki Itoh
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 7 Pages 2063-2067
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We determined the crystal structure of RbDSO4 in the paraelectric phase by X-ray diffraction study. The structure is isomorphous to the paraelectric structure of undeuterated RbHSO4. There are two kinds of RbDSO4 molecules in the unit cell. One of the SO4 ions takes disordered molecular arrangements. Both kinds of the D atoms are located acentrically in the hydrogen bonds and combine the ordered and disordered SO4 ions, respectively. The D atom combining the disordered SO4 ion executes very large thermal vibrations and its nature can be understood by the riding model, in which the D atom displaces in phase with the disordered motion of the closer SO4 ion.
    Download PDF (433K)
  • Hirosi Okamoto
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 2068-2074
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    A renormalization group treatment is applied to a model of (quasi)-two-dimensional semiconductor with a small band gap. Phase diagrams are derived based on the numerical solutions of the scaling equations. In the purely two-dimensional case, we find the singlet superconducting phase is induced by the repulsive interband interaction in the presence of the attractive intraband interaction. We also find the ferromagnetism and/or the ferroelectricity are stabilized in the presence of the repulsive interband and intraband interactions. The effects of the other kinds of interband and interplanar interactions are also discussed.
    Download PDF (538K)
  • Koichi Kusakabe
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 2075-2085
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The extended spectral flow at the normal-superconducting transition is investigated for the one-dimensional Hubbard model. Recombination of spectral flow lines at U=± 0, which causes halving of the extended Aharonov-Bohm period for U<0 found in a recent paper [K. Kusakabe and H. Aoki: J. Phys. Soc. Jpn. 65 (1996) 2772], is exactly analyzed using the Bethe ansatz solution. Adiabatic motion of charge rapidities which are real for U>0 (normal Luttinger liquid) or complex for U<0 (superconducting Luther-Emery liquid) dominates sudden response of the spectral flow at the transition point. The extended period is obtained not only against the charge flux but also against the spin flux for both U>0 and U<0.
    Download PDF (885K)
  • Ryotaro Arita, Koichi Kusakabe, Kazuhiko Kuroki, Hideo Aoki
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 7 Pages 2086-2096
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The `extended Aharonov-Bohm (AB) period' recently proposed by [K. Kusakabe and H. Aoki: J. Phys. Soc. Jpn. 65 (1996) 2772] is extensively studied numerically for finite size systems of strongly correlated electrons. While the extended AB period is the system length times the flux quantum for noninteracting systems, we have found the existence of the boundary across which the period is halved or another boundary into an even shorter period on the phase diagram for these models. If we compare this result with the phase diagram predicted from the Tomonaga-Luttinger theory, devised for low-energy physics, the halved period (or shorter periods) has a one-to-one correspondence to the existence of the pairing (phase separation or metal-insulator transition) in these models. We have also found for the t-J model that the extended AB period does not change across the integrable-nonintegrable boundary despite the totally different level statistics.
    Download PDF (913K)
  • Kazutomo Suenaga, Christian Colliex, Catherine Sant, Sid Labdi, Philip ...
    Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
    1997 Volume 66 Issue 7 Pages 2097-2102
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Compositionally modulated TiNx multilayers (0.33 peak, so-called white line, broadens in accordance with the nitrogen concentration, due to a change in the d band occupation. A shift of the volume plasma frequency towards lower energies when the nitrogen vacancy concentration increases is observed and explained in terms of a simple free-electron gas model. These results demonstrate the great power of spatially resolved electron energy loss spectroscopy as a probe of electronic structure with subnanometer-scale spatial resolution.
    Download PDF (589K)
  • Atsuo Isobe, Masaaki Yamada, Kazuhide Tanaka
    Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
    1997 Volume 66 Issue 7 Pages 2103-2109
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    The Ni_xSi100-x system forms a homogeneous amorphous phase over wide ranges of composition (0≤ x≤ 34 and 63≤ x≤ 73) when the alloy is deposited on a substrate by sputtering at ambient temperature. The electrical conductivity of the amorphous alloy changes characteristically with Ni concentration from a semiconductor-like temperature dependence to a metallic one, the transition taking place between 10.4 and 16.6% Ni. UPS valence band spectra show that the density of states at the Fermi level is minimal below about 7% Ni, but emerges abruptly above this concentration. The relationship between the electrical transport properties and the electronic structure of the amorphous alloys is discussed in three characteristic regions of the Ni concentration.
    Download PDF (590K)
  • Hikaru Kawamura, Mai Suan Li
    Subject area: Superconductivity.
    1997 Volume 66 Issue 7 Pages 2110-2122
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    Possible occurrence of an equilibrium thermodynamic phase with a spontaneously broken time-reversal symmetry is studied in a model ceramic superconductor with anisotropic pairing symmetry. It is shown by Monte Carlo simulations that such a “chiral-glass” phase is truly stable even under the influence of screening. Existence of frustration in zero external field, arising from the d /-wave pairing symmetry of high-Tc superconductors, is essential to realize this phase. Via a finite-size scaling analysis, critical exponents associated with the chiral-glass transition are estimated to be ν CG=1.3± 0.2 and η CG=-0.2± 0.2. These values turn out to be close to those of the Ising spin glass. Phase diagram of the model is constructed and the implications to experiments are discussed.
    Download PDF (1150K)
  • Yuuki Watanabe, Seiji Miyashita
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 2123-2128
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We investigate the magnetization of the ground state of the one-dimensional flat-band Hubbard model as a function of the electron filling, using exact diagonalization techniques. Our calculation shows that the systems with odd n holes added to half-filling bands for a sufficiently large U (the on-site Coulomb repulsion energy) have a saturated ferromagnetic ground state, which is nondegenerate except for the trivial spin degeneracy. Dependences of the critical value of U on the size and on λ (a parameter of the system) are also investigated. For all values of λ, it is found that the ground state is a saturated ferromagnetic state if U is sufficiently large. Moreover, we find that the critical U for the saturated ferromagnetic ground state is almost independent on the system size, at least, for the system near quarter-filling. These facts indicate that even if the system size go to infinity, the ferromagnetic ground state can be exist for a finite U.
    Download PDF (485K)
  • Takuya Okabe
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 2129-2132
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We derive expressions required in generalizing the Gutzwiller approximation to models comprising arbitrarily degenerate localized orbitals.
    Download PDF (196K)
  • Kazunori Umeo, Toshiro Takabatake, Noriaki Sato, Takemi Komatsubara, K ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 2133-2137
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We report on the magnetic, transport, and thermal properties of a heavy-fermion antiferromagnet Ce7Ni3. The Ce ions in the three nonequivalent sites are found to be very close to trivalent from LIII X-ray absorption spectroscopy and magnetic susceptibility measurements. The magnetic susceptibility along the c axis exhibits a pronounced peak at the Néel temperature TN=1.9, K, while that along the b axis defined perpendicular to the a axis shows a rounded maximum at 0.6, K. The magnetization curve for B//c at 1.4, K exhibits a metamagnetic transition at 0.2, T, and reaches a value of 1.0, μ B/Ce at 36, T. The electrical resistivity ρ (T) for I//c turns up below TN, whereas those for I//a and I//b decrease. These results suggest that the antiferromagnetic order creates a partial gap along the c axis on the Fermi surface. The magnetic entropy due to 4f electrons reaches 0.47R ln 2 at TN. The magnetic moment and magnetic entropy in the antiferromagnetic state are substantially reduced by the combination of the Kondo effect and crystalline electric field (CEF) effect. The Kondo temperature and energy of the first CEF level are estimated to be 7, K and 240, K, respectively, by the analysis of the specific heat.
    Download PDF (454K)
  • Junya Sasaki, Fumitaka Matsubara
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 2138-2146
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    We make a large-scale Monte Carlo (MC) simulation of a ferromagnetic Heisenberg model with dipolar interactions on a two-dimensional square lattice L× L with open boundaries. We find that, as L is increased, the spin structure changes from a ferromagnetic one to a novel one characterized by a circular arrangement of spins. We suggest that, in the thermodynamic limit, a long-range circular phase occurs in the cooperation of the exchange and the dipolar interactions and that the phase transition between the paramagnetic phase and the circular phase is of the second order. In this study, we develop a discrete update MC method which reduces the CPU time from of the order N^2 to Nlog_2N per one MC sweep, where N is the number of the spins.
    Download PDF (654K)
  • Masaki Mito, Hiroyuki Nakano, Tatsuya Kawae, Masako Hitaka, Seishi Tak ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 7 Pages 2147-2156
    Published: July 01, 1997
    Released on J-STAGE: October 01, 1999
    JOURNAL RESTRICTED ACCESS
    A genuine organic radical crystal 1, 3, 5-triphenyl-6-oxoverdazyl (TOV) has been revealed to be an S=1/2 two-dimensional (2D) weak-ferromagnetic Heisenberg antiferromagnet with the exchange interaction 2J/kB=-9.0, K by the experiments of magnetic susceptibility, heat capacity, magnetization and electron paramagnetic resonance. The anomalous temperature dependence of the weak ferromagnetism at low temperatures is qualitatively explained by a four-sublattice model with two kinds of Dzyaloshinsky-Moriya (D-M) vectors of opposite sign on the ac-plane. The staggered susceptibility, which is a fictitious but intrinsic quantity for antiferromagnets, is estimated in TOV by making use of the canted weak ferromagnetic moments which dominate below 6, K. Especially the rapid growth of the magnetic susceptibility below 6, K is explained by the staggered susceptibility which makes the crossover effect from 2D Heisenberg to 2D Ising system, triggered by above the D-M anisotropy.
    Download PDF (821K)
feedback
Top