Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 66, Issue 6
Displaying 1-50 of 53 articles from this issue
  • Sanae –I. Itoh, Kimitaka Itoh
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1997 Volume 66 Issue 6 Pages 1571-1574
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    A spectrum of fully developed turbulence via subcritical excitation in an inhomogeneous plasma is obtained. The dressed-test-mode analysis is developed, in which a dielectric tensor containing renormalized transfer rates is solved. The energy spectrum of the form E(k)∝ G0k-3 is obtained in the energy-containing region. (G0 denotes the driving, which is the product of the gradients of plasma pressure and magnetic field.) Turbulent kinetic energy, W∝ G02, and transport coefficient, χ T∝ G03/2, are found to be nonlinear functions of G0, which presents a typical example of nonlinear, nonequilibrium transport.
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  • Kazuhiro Fuchizaki, Masaharu Isobe, Yasuhiko Fujii, Kyoko Sato, Nozomu ...
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 6 Pages 1575-1578
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Isothermal-isobaric molecular dynamics simulations of molecular crystal SnI_4 are carried out based on a model consisting of rigid tetrahedral molecules interacting via van der Waals forces. The behavior of the crystal upon an increase in pressure is satisfactorily reproduced on both microscopic and macroscopic scales in the pressure regime in which the low-pressure phase is stable. In particular the compression curve obtained is in excellent agreement with the experimentally determined one. Upon further increase in pressure, however, no symmetry change is detected in the present simulations over the pressure regime in which the phase transformation and the subsequent solid state amorphization are experimentally found to take place.
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  • Atsushi Mori
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 6 Pages 1579-1582
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Following a previous molecular dynamics investigation on thehard-sphere crystal-melt interface, effects of mass flow in themelt on the interface motion are reported. After preparingsystems using the method of Mori et al. [Phys. Rev. E51 (1995) R3831], slight initial flow velocities were addedto the melts. Interface motions caused by the density increase anddecrease due to the flow were observed. It is shown that thisphenomena can reasonably be understood from the viewpoint of massconservation.
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  • Duk Joo Kim
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1583-1586
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    By reexamining the RPA electron self energy for a single band long range Coulomb interaction model of electrons, we raise the possibility that in a metal the electron-plasmon interaction, which is the dominant ingredient of the RPA consequence, may drive a band to split into three when the plasma frequency, ω pl, is larger than the band width, W. The behavior of the band splitting is found to depend very sensitively on the unscreened exchange interaction between electrons, U, besides ω pl, W, and the number of electrons per atom. We show that when U is much larger than W, such band splitting may induce a metal-insulator transition.
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  • Tadao Kasuya, Dexin Li
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1587-1590
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Long-standing puzzling anomalous properties in Yb monopnictides are studied in detail with a novel new idea of paired Jahn-Teller distortion and charge dipolar ordering accompanied by compatible magnetic dipole ordering. The paired distortion occurs at around 50, K, commonly with an energy splitting of several meV. This is consistent with other systems that show similar paired Jahn-Teller distortion. Anomalous specific heat induced by level splitting, including the magnetic singlet ground state due to an antiferromagnetic pair exchange interaction, is observed as a two-peak structure with the lower peak around 5, K in common. A Néel transition at a low temperature of around 0.5, K in common is primarily a charge dipolar ordering due to pair ordering and occurs in competition with the pair singlet state, causing a weak transition with a small ordered moment. The above common features are caused by a strong-pair antiferromagnetic exchange interaction with nearly equal strengths.
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  • Arata Tanaka, Takeo Jo
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1591-1594
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We calculate a resonant inverse photoemission spectroscopy (IPES) spectrumat the Ni 3p core threshold (3dn → 3p53dn+2 → 3dn+1), from a viewpoint of a many-bodyconfiguration interaction (CI), on the basis of the Anderson impurity model. The calculated IPES spectrum exhibits a single main peak just above theFermi level EF under off-resonance, while it has a shoulder extending to 4 eV aboveEF under on-resonance conditions. Under on-resonance conditions, the main peak intensity shows a dip whosemagnitude is a function of the incident electron energy ε, while the shoulder isresonantly enhanced. The interference between the direct 3d8 → 3d9 and resonant 3d8 → 3p53d10 → 3d9 processesand CI in both the initial and final states leads to the above result.Resonant IPES is therefore considered to be a promising method of directlydetermining whether a 3d8 configuration in the initial state, inferred by analysis of various high-energy spectroscopic data, does in fact exist.The main peak is assigned to the bonding state of 3d10 and 3d9configurations and the shoulder a non-bonding and the anti-bonding states of them.
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  • Masahiko Hiroi, Masafumi Sera, Norio Kobayashi, Yoshinori Haga, Etsuji ...
    Subject area: Superconductivity.
    1997 Volume 66 Issue 6 Pages 1595-1598
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have studied the thermal conductivity κ and electrical resistivity ρ of UPd2Al3 single crystal in the temperature range between 0.36, K and 70, K in magnetic fields up to 5, T. At high temperatures, the thermal conductivity is dominated by phonons. Below the Néel temperature TN=14.5, K, κ shows an enhancement compared with the extrapolated behavior from the higher temperature than TN, which is associated with the steep decrease of ρ . This suggests the increase of the electron contribution to κ below TN due to the decrease of the magnetic scattering. The temperature dependence of κ does not show an anomaly at Tc and shows a T2 behavior below 1, K, which suggests that the superconducting gap in UPd2Al3 vanishes along lines on the Fermi surface. κ in magnetic field shows clearly a larger decrease below Tc than above Tc with decreasing temperature, which is very different from the temperature dependence of κ in zero magnetic field.
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  • Takashi Kimura, Kazuhiko Kuroki, Hideo Aoki
    Subject area: Superconductivity.
    1997 Volume 66 Issue 6 Pages 1599-1602
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The quantum Monte Carlo method is used to investigate the superconductivity in the three-leg Hubbard ladder. The enhanced correlation for the pairing across the central and the edge chains, which has been predicted to occur in the weak-coupling renormalization as an effect of the coexistence of gapful and gapless spin modes, is shown here to persist for intermediate interaction strengths.
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  • Ryusuke Ikeda
    Subject area: Superconductivity.
    1997 Volume 66 Issue 6 Pages 1603-1606
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The scaling behavior of dc conductivity σxx in a current perpendicular to the magnetic field near a vortex-glass (VG) transition is addressed in terms of the Ginzburg-Landau (GL) model and Kubo formula and by assuming a universal scaling behavior of the VG correlation function. Together with the uncorrelated Tc-disorder, we also take account of another type of uncorrelated disorder which becomes a familiar expression once assuming the phase-only approximation. Based on a calculation perturbative in the pinning disorders, we show that both of these uncorrelated disorders are necessary in order to obtain the universal scaling of σxx proposed by Fisher et al. [Phys. Rev. B 43 (1991) 130], and that, if either of them is negligible, the scaling behavior of σxx can be apparently nonuniversal even deep in the VG critical region. Our results explain, without invoking a possible destruction of true VG transition due to screening, why the vanishing resistivity data show a nonuniversal behavior with a field-dependent exponent in situations with point disorder suppressing the first-order transition.
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  • Hiroshi Kageyama, Kazuyoshi Yoshimura, Koji Kosuge, Hiroyuki Mitamura, ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1607-1610
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Magnetization measurements on the one-dimensional oxide Ca3Co2O6 having a triangular net of Co2O6 chains have been carried out both in static and pulsed high magnetic fields. The M/H vs. T curve obeys the Curie-Weiss law at high temperatures. Below 25 K, however, M/H increases abruptly, and a plateau is observed at 1/3 of the full moment in the M-H curve, suggesting a ferrimagnetic state of the ferromagnetic chains due to the antiferromagnetic interchain interaction. At low H, this system is considered to be in a partially disordered antiferromagnetic state for 10 K
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  • Ken–ichi Takatsu, Wakako Shiramura, Hidekazu Tanaka
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1611-1614
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The magnetic susceptibilities of S=1/2 double spin chain systems, TlCuCl3, NH4CuCl3 and KCuBr3, which are isomorphous with KCuCl3 have been measured using single crystals and polycrystals. The exchange interactions in a double chain can be described by a Heisenberg spin ladder with an additional diagonal interaction. It is found for TlCuCl3 and KCuBr3 that with decreasing temperature the susceptibilities for different external field directions exhibit broad maxima at 38, K and 130, K, respectively, and decrease exponentially to zero as observed in KCuCl3. This result indicates that their ground state is a spin singlet with an excitation gap. This behavior is attributed to the quantum effect characteristic of the spin ladder system. For NH4CuCl3, the susceptibility of polycrystals displays a round maximum at 4.5, K and decreases with a tendency toward zero, which implies the nonmagnetic ground state.
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  • Yasuo Endoh, Tatsuo Fukuda, Kenji Nakajima, Kazuhisa Kakurai
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1615-1617
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The spin fluctuation mode of magnetic excitations in the spin densitywave (SDW) state of metallic chromium (Cr) was analyzed by means ofpolarization analysis of neutron scattering. Commensurate scatteringcentered at the antiferromagnetic superlattice position ofπ/a(1, 0, 0) is dominated by the longitudinal mode both below andabove the threshold energy of 8 meV with a different ratio againstthe transverse mode. On the other hand, magnetic excitationswith the wave vector of the static SDW were confirmed to be mostlylongitudinally polarized below 8 meV, but the scattering mode abovethis threshold energy was nearly isotropic.
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  • Takafumi Momose, Toshihiko Suzuki, Yuhei Natsume
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1618-1621
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Thermodynamic properties of spin=1/2 two-leg ladders with alternating chains including ferromagnetic and antiferromagnetic interactions are discussed on the basis of the numerical results obtained by quantum Monte Carlo simulations. As well as the role of exchange interaction of rungs, the essential role of the bond alternation in the chain on ladder systems is investigated in connection with the appearance of characteristic properties in magnetic susceptibilities and heat capacities. Furthermore, quantum effects on the ground-state energy are obtained. On the basis of calculated results, the relationship between singlet dimer phases and Haldane states is discussed.
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  • Jun Kikuchi, Touru Yamauchi, Yutaka Ueda
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1997 Volume 66 Issue 6 Pages 1622-1625
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have observed a marked frequency (ω ) dependence of the 31P nuclear spin-lattice relaxation rate 1/T1 in the spin-1/2 two-leg ladder compound (VO)2P2O7 at temperatures well above the spin gap. The 1/T1 is found to show an ω -1/2 dependence above a certain cutoff frequency, indicating one-dimensional diffusive spin dynamics along the leg of ladders. We have also found that the spin-diffusion constant increases rapidly with decreasing temperature. This may be related to the increase of the antiferromagnetic correlation length within the ladder at low temperatures.
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  • Mihiro Yanagihara, Noboru Miyata, Takeo Ejima, Makoto Watanabe, Yosuke ...
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1997 Volume 66 Issue 6 Pages 1626-1629
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have investigated the anisotropy of the spectra and the polarization degree of the B 1s emission in hexagonal boron nitride using synchrotron radiation as a light source. Spectator emission appears when the B 1s hole is radiatively filled with the valence electron while the core exciton state being occupied. It has been found that π emission is absent or very weak in the spectator emission, while both π and σ components are present in the normal emission. This result has been explained in terms of the Coulombic effect of the core hole on the localized B 2pz valence orbital.
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  • Sachiko Koseki, Hidetomo Hirao, Hiroshi Takano
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 6 Pages 1631-1637
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The relaxation modes and rates of a single polymer chain are studied by Monte Carlo simulations of the bond fluctuation model. On the basis of the method proposed by Takano and Miyashita [J. Phys. Soc. Jpn. 64 (1995) 3688], the approximate relaxation modes and rates are obtained by solving a generalized eigenvalue problem for the correlation matrices Ci,j(t)=‹ Ri (t) · Rj (0) › / 3 , where Ri (t) denotes the position of the ith segment relative to the center of mass of the polymer chain. For a chain of N segments with the excluded volume interaction, the contribution ˜{g}i,p of the pth slowest mode to Ri shows the i-dependence ˜{g}i,p ∝ cos [(i-½)p π / N], which is the same as that of the Rouse model. The behavior of the relaxation rate λ_p of the pth slowest mode is in good agreement with the theoretical prediction λ_p -- (p/N)2ν + 1, where ν ~= 0.588 is the exponent for the swelling of a polymer chain in good solvent.
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  • Atsuko Takamatsu, Kengo Takahashi, Makoto Nagao, Yoshimi Tsuchiya
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 6 Pages 1638-1646
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Gathering or escaping behavior in the plasmodium of Physarum polycephalum is considered to relate to an entrainment of the coupled nonlinear oscillators. The behavior has been explained to be caused by the formation of phase gradient between those oscillators, which results from the local frequency modulation at the stimulated site. However, it has not yet been elucidated how the formation process relates to the migration of the plasmodium. In this paper, we have introduced a model with frequency coupling besides the phase coupling in the system of coupled oscillators. By the simulation, we have shown that not only the phase gradient but also the concentration gradient of substances such as Ca2+ and ATP are self-organized and their reverse by the stimulus results in the migration of plasmodium.
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  • Hidetoshi Miike, Tatsunari Sakurai, Atsushi Osa, Etsuro Yokoyama
    Subject area: Measurement science, general laboratory techniques, and instrumentation systems.
    1997 Volume 66 Issue 6 Pages 1647-1655
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We propose a method to measure Brownian motion based on image sequence processing. Random motion of sub-micron sphere particles is visualized under an inverted microscope with laser light illumination. We analyze a long image sequence of the motion by a spatial-filtering method, which corresponds to dynamic light scattering. We confirm that bigger particle (diameter=1.09 μm) show ideal Brownian motion with an inverse power-law spectrum P(f)∝ f-2. In tiny particles (diameter=0.46 and 0.20 μm), however, we observe a deviation from f-2 behavior. When the motion of particles is limited within a two-dimensional plane by use of heavy water, ordinary behavior of f-2 spectrum is recovered. We confirm high reliability and big advantages of the proposed method compared to dynamic light scattering.
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  • Jun Nakamura, Hidekazu Konogi, Hiroshi Sato, Toshiaki Osaka
    Subject area: Electronic structure of atoms and molecules: theory.
    1997 Volume 66 Issue 6 Pages 1656-1659
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Chemical bonding states for a series of MX4 (M=C, Si, Ge, X=F, Cl, Br, I) molecules have been studied with use of self-consistent-charge-Xα calculations. The results show that the s-character, s/(s+p) of the sp3-hybridized orbitals of M atoms changes every MX4 molecules, to which the electronegativity of the M-sp3 orbitals is in a linear relationship. These findings assist to understand chemical bonding features which are inherent in these quadricovalent molecules.
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  • Jae–Tack Jeong, Chan–Guk Park
    Subject area: Fluid dynamics.
    1997 Volume 66 Issue 6 Pages 1660-1667
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Two-dimensional slow viscous uniform flow past a lattice of equal parallel and equidistant flat plates is investigated based on the Stokes' approximation. The plates are at rest and the flow is generated by a pressure difference between two sides of the lattice at infinity. By solving a three-part Wiener-Hopf equation, analytic expression for the stream function is obtained for a parameter a, where a is the length of the plate. Drag force exerted on the plate is calculated and pressure and shear stress distributions are shown. The asymptotic form of the drag for a→ 0 is obtained by considering a pair of dual integral equations. Local analysis for the flow near the edge of the plate is also included.
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  • Ken–ichi Matsuba, Kenji Imai, Kazuhiro Nozaki
    Subject area: Fluid dynamics.
    1997 Volume 66 Issue 6 Pages 1668-1671
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We give three types of exact solutions (a hole, a solitary wave and a shock) of the Davey-Stewartson equation with complex coefficients, which is a kind of 2+1 dimensional generalization of the 1+1 dimensional complex Ginzburg-Landau equation.
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  • Akihide Takeda, Nobuaki Ikuta
    Subject area: Kinetic and transport theory of fluids; physical properties of gases.
    1997 Volume 66 Issue 6 Pages 1672-1687
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Under homogeneous electrostatic field in gas between two plane electrodes, the electron energy distribution and transport properties near the electrodes are usually position dependent. Boltzmann equation analyses for such position dependent energy distribution and transport properties in steady state are very few due to its difficulty. In this paper, position dependent electron behaviors in CF4 calculated using the Steady State Townsend flight time integral method (SST-FTI) for several boundary conditions are presented with the theory of the SST-FTI.
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  • Ching–Jiun Wu, Jiang–Tsu Yu
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 6 Pages 1688-1692
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The EPR spectra exhibited by the doped Cr3+ ions is sensitive to the reported low-temperature ferroelectric transition in N2H5Al(SO4)2· 12H2O crystals. Structural informations that can be deduced from the experimental results include: (1) the appearance of merohedral twinning is concurrent with the onset of the structural phase transition; (2) the crystalline threefold symmetry, which is lost with the onset of the structural phase transition, becomes the twin law relating the orientations of the component domains; (3) the crystal symmetry below the transition temperature is orthorhombic; (4) the crystalline cubic axes of the high-temperature, cubic phase become the three crystalline twofold axes of the low-temperature, orthorhombic phase; and (5) a single Cr3+ species is detected in both the cubic and the orthorhombic phases, which implies that all the Al3+ sites are crystallographically equivalent in both phases.
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  • Hisashi Sasaki, Hiroshi Harashina, Satoshi Taniguchi, Mayumi Kasai, Yo ...
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 6 Pages 1693-1697
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Structural studies of La3Ni2O6.92 with a double layered perovskite structure have been performed by the X-ray Rietveld analyses between 300, K and 650, K. The interatomic distance between Ni and the apical oxygen (on the outside of NiO2 double layer) rapidly increases around the phase-transition temperature TB -- 550, K with decreasing temperature. Then, the energy of the (3z2-r2) band is considered to shift downwards with respect to that of the (x2-y2) band with decreasing temperature and the lower Hubbard band of the former becomes to be (almost) fully occupied at the transition temperature, which induces the Mott transition (delocalized-localized transition) of the (3z2-r2) electrons.
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  • Yoshihiro Kuroiwa, Masanosuke Kunikata, Hideo Honda, Yukio Noda, Eiji ...
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 6 Pages 1698-1701
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Phase transitions in intercalation compounds Mn_xNbS2 and Mn_xTaS2 (x=1/4 and 1/3) have been investigated at high-temperature region using a magnetic balance and an X-ray diffractometer. In Mn1/4NbS2, the discontinuous changes of the magnetic susceptibility and the lattice parameter c are observed at 640 K. In Mn1/4TaS2, similar discontinuities are observed at 670 K. From the temperature dependence of the superlattice reflections, it has been found that these discontinuities are manifestation of the structural phase transition associated with the order-disorder of the intercalated Mn atoms and the displacement of the Nb, Ta and S atoms.
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  • Masayuki Hagiwara, Kimiko Kobayashi, Teiji Chihara
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 6 Pages 1702-1706
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have studied crystal structures of a Ni bond alternating chain compound [ {Ni2(Medpt)2(μ-ox)(μ-N3)}n] {(ClO4)·0.5H2O}n (Medpt=methyl-bis(3-aminopropyl)amine, ox=C2O4) (1) and a Nidimer compound [Ni2(dpt)2(μ-ox)(H2O)2] (NO3)(PF6) (dpt=bis(3-aminopropyl)amine) (2) by x-ray diffraction. Both title compounds crystallize in the triclinic system, space group P\bar{1} with fw=646.41, a=8.032(1)Å, b=13.436(1)Å, c=13.968(2)Å, α=63.84(1)°, β=80.54(1)°, γ=81.29(1)°, V=1329.3(2)Å3, Z=2, R=0.067 and Rw=0.075 for 1 and with fw=710.88, a=8.814(1)Å, b=12.255(1)Å, c=13.487(1)Å, α=81.16(1)°, β=89.57(1)°, γ=88.53(1)°, V=1439.0(1)Å3, Z=2, R=0.059 and Rw=0.068 for 2. Thedifference of chain structures between 1 and a similar bond alternating compound [ {Ni2(dpt)2(μ-ox)(μ-N3)}n](PF6)n is discussed.
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  • Jun Suda, Tsutomu Sato
    Subject area: Lattice dynamics and crystal statistics.
    1997 Volume 66 Issue 6 Pages 1707-1713
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The first-order Raman spectra of Ag(1), Ag(2)+Bg(2) and Bg(1) modes in CaWO4 crystal were measured in the temperature range of 77--771, K and the linewidths at these temperatures were obtained. The temperature dependence of the linewidths was analyzed using the phonon dispersion curves calculated on the basis of a rigid-ion model, and the results showed that it was caused approximately by the cubic anharmonic term in the crystal potential energy.
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  • Sadhna Singh, R. K. Singh
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 6 Pages 1714-1717
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Phase transition pressure, relative volume change and mechanical properties of partially covalent Indium antimonide have been studied. A potential model has been developed which includes Coulombic, three body interactions, van der waals forces, overlap repulsive interaction and covalency effects operative upto second neighbour ions. It is found that the inclusion of covalency effect has improved the results.
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  • Jun Takeda, Yukio Yasui, Hisashi Sasaki, Masatoshi Sato
    Subject area: Thermal properties of condensed matter.
    1997 Volume 66 Issue 6 Pages 1718-1722
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Measurements of the linear thermal expansion coefficient α have been carried out on both polycrystalline pellets and single crystals of BaCo1-xNixS2, which has a layered structure and exhibits the Mott transition with varying x. In the region of x≤ 0.22, where antiferromagnetic state exists below TN, α exhibits the finite discontinuity Δα at TN, as is expected in ordinary cases of second order phase transition. The sign of the discontinuity Δα {≡ α (TN-0)-α (TN+0)} changes from positive to negative at x-- 0.07 with increasing x, which can consistently be explained by considering the x-dependence of the electronic structure of this system.
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  • Takeo Fujiwara, Takeo Hoshi
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1723-1729
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Optimization of ultrasoft pseudopotentials is discussed from two points, i.e. (1) parametrization and function forms ofpseudo-wavefunctions and local part of pseudopotentials, and (2) pseudization of augmentation charge.The cutoff energy for the Fourier components of the non-local partof the ultrasoft pseudopotential should be carefully chosen, because calculated cohesive energy often changes drastically with a change of the cutoff energy for the non-local part. Proposed optimization for the pseudized augmentation charge canefficiently make short wavelength components vanish. Examples of pseudopotentials are shown for a carbon atom. Charge density and cohesive energy are exemplified for diamond.
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  • Harumi Hikita, Kosei Takeda, Yutaka Kimura, Haruo Yokomichi, Kazuo Mor ...
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1730-1740
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    It is shown that ESR spectra of dangling bonds in a-Si:H for glow discharge samples are deconvoluted into two components due to normal dangling bonds and H-related dangling bonds. The component for H-related dangling bonds has anisotropic g-values and anisotropic hyperfine coupling constants of 1H. The distance between the dangling bond site and hydrogen site is estimated to be 2, Å, using a tight binding theory. The normal dangling bonds constitute about 60\H-related dangling bonds give about 40\samples were also illuminated by a xenon lamp with 600, mW/cm2 at room temperature. The normal dangling bonds and H-related dangling bonds are created almost equally by illumination.
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  • Ryousuke Shiina, Hiroyuki Shiba, Peter Thalmeier
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1741-1755
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    A theory of the antiferro-quadrupolar ordering in CeB6 is developed in the framework of the Γ8-quartet basis. Possible ordered phases under the external magnetic field are classified in terms of their symmetry properties, and the relations between quadrupolar order parameters and field-induced moments are established. Then we formulate a mean-field theory of Ohkawa's RKKY model based on the group-theoretical consideration. The stability of the possible phases and the resulting phase diagrams are analyzed in connection with the character of quadrupolar moments, the influence of induced moments and the form of Zeeman term. Considering available experimental results, we introduce an improved model with asymmetric interactions and discuss the phase diagram of CeB6. The connection between magnetostriction and uniform quadrupolar moments is discussed.
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  • Naoyuki Nagasako, Tamio Oguchi, Hideki Fujisawa, Osamu Akaki, Takayosh ...
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 6 Pages 1756-1761
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The energy band structure of a quasi one-dimensional cuprate SrCuO2 is studied by angle-resolved photoemissionspectroscopy and the linear augmented-plane-wave band structure calculationwithin local density approximation. It was found that the band structure has strongly one-dimensional nature with a finite dispersion along the Cu-O chains.The calculated band structure of SrCuO2 is in good agreement with theangle-resolved photoemission result except for the region near the Fermi level.
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  • Masahiko Hiroi, Sumio Kobayashi, Masafumi Sera, Norio Kobayashi, Sator ...
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 6 Pages 1762-1770
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have studied the magnetoresistance of CexLa1-xB6 (x=0.25, , 0.5, , 0.75) single crystals under the magnetic fields up to 15, T and in a temperature range between 0.4, K and 15, K. In Phase I (paramagnetic), in all the samples the negative magnetoresistance is observed, whose magnitude becomes larger with decreasing temperature. However, in Ce0.5La0.5B6, the magnetoresistance below T-- 1, K becomes very small neverthless the negative magnetoresistance is observed above -- 1, K. This is completely different from the magnetoresistance in Ce0.25La0.75B6 where the magnitude of the negative magnetoresistance becomes larger with decreasing temperature. The weak magnetic field dependence of the electrical resistivity is observed also in Phase IV in Ce0.75La0.25B6. These results indicate that the ground state of Ce0.5La0.5B6 is not the Kondo singlet but the AF (antiferro) magnetic state called Phase VI is realized below -- 1, K. Phase IV is similar to Phase IV in Ce0.75La0.25B6. The anisotropy of the phase boundaries between I, II (AFQ (antiferroquadrupolar) ordered), III (antiferromagnetic ordered) and IV in Ce0.5La0.5B6 has been studied. The phase boundary I--IV does not show the anisotropy but that of III--II shows the large anisotropy depending on the applied field direction. These are discussed from the stand point that the magnetic anisotropy and the intereference effect between the AFQ and AF interaction are important. We propose the mechanism of the phase transition from IV to III or II.
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  • Hidetoshi Minami, Hiromoto Uwe
    Subject area: Superconductivity.
    1997 Volume 66 Issue 6 Pages 1771-1775
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Mechanism of electrical conductivity in the normal state of the perovskite-type oxide superconductor Ba0.58K0.42BiO2.96 has been investigated by measuring the conductivity and the Hall coefficient in the temperature range of 20--300, K, using a single crystal which seems to exhibit the intrinsic feature of conductivity because of the small residual resistivity value of 1× 10-4, Ω · cm. The best analytical fit of temperature dependence of resistivity is obtained assuming scattering of the electron by both the acoustic phonon with the Debye temperature of 320, K and the optical phonons with the Einstein temperatures of 835, K and 460, K. The small value of the Hall mobility of about 2, cm2/V· s at room temperature means strong interaction of electrons with phonons. We emphasize the important role of electron-LO phonon interaction in the mechanism of conductivity.
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  • Chikara Manabe, Migaku Oda, Masayuki Ido
    Subject area: Superconductivity.
    1997 Volume 66 Issue 6 Pages 1776-1784
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Atomic images of the Bi--O and Cu--O planes were selectively observed in STM experiments on slightly underdoped Bi2Sr2CaCu2O8+δ by changing bias voltage, and tunneling spectra were measured while observing the Cu--O plane at three tip heights (h1>h2>h3). The Cu--O plane images indicate that the conduction holes go mainly into O 2pσ and Cu 3dx2-y2 orbitals. The spectra for h1 and h2 are consistent with a gap having lines of nodes at the directions 45° from the Cu--O bonds, as shown in our previous work. On the other hand, the spectra for h3, where the tip seems to be very close to the specimen surface, are quite similar to expectations for the pair-breaking due to non-magnetic impurities in a d-wave superconductor. This, combined with the result for the node directions, strongly supports a dx2-y2 superconducting gap.
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  • Takehiko Hihara, Kenji Sumiyama, Hideya Onodera, Kimio Wakoh, Kenji Su ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1785-1791
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Magnetic properties and magnetoresistance (MR) have been studied in homogeneous and granular FexCu100-x films produced by sputter (SP)-deposition and subsequent annealing. Concentration dependence of the MR ratio shows a maximum at x=20 in the as-SP-deposited films. On the other hand, it shows a monotonic change (no maximum) after annealed at 673, K for 30, min. Such an MR variation by annealing is ascribed to the magnetic transition of Fe clusters in Cu matrices. Mössbauer spectra and thermomagnetic curves observed at low temperatures indicate that the as-SP-deposited FexCu100-x alloy films are f.c.c. for x<35 being spin-glass, while those ones annealed at 673, K for 30, min are f.c.c. and b.c.c. mixture, being a spin-glass and ferromagnetic complex for x=11 and an antiferromagnetic and ferromagnetic one for x=20.
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  • Masayuki Hagiwara, Yasuo Narumi, Koichi Kindo, Tatsuo C. Kobayashi, Hi ...
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1792-1795
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    We report the results of susceptibility and magnetization measurements on ferromagnetic-antiferromagnetic alternating chain compounds [Cu(TIM)]CuCl_4 (TIM=2, 3, 9, 10-tetramethyl-1, 3, 8, 10-tetraenecyclo-1, 4, 8, 11-tetraazatetradecane) and (4-BzpipdH)CuCl_3 (4-BzpipdH=4-benzylpiperidinium). Magnetization curves of both compounds are compared to those calculated for an S=1 linear-chain Heisenberg antiferromagnet. From the fitting of susceptibility data to a numerical formula calculated for an S=1/2 ferromagnetic-antiferromagnetic alternating chain [Inog. Chem. {33} (1994) 5171], we have estimated theantiferromagnetic exchange constant JAF/kB=2.9 K, the ferromagnetic exchange constant |JF|/kB=4.7 K and the g-value of the magnetic moment g=2.06 for the former and JAF/kB=8.8 K, |JF|/kB=38.8 K and g=2.17 for the latter, which are different from the values reportedpreviously.
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  • Kiyosi Terao
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1796-1802
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The complicated spin configuration observed in YMn2 with the cubicLaves phase (C15) structure is deduced through the exchange interactionsbetween the second and/or third neighbors together with the antiferromagneticinteraction between the nearest neighbors, by making use of the Luttinger-Tiszamethod on the classical spin Heisenberg model. The spin configuration isdescribed with a modulation wave vector pointing at the X point on theBrillouin zone boundary and shown to be stable with respect to its smalldeviations, i.e., long range modulations.
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  • Katsuyasu Kawano, Kazuo Katoh, Ryouhei Nakata
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1997 Volume 66 Issue 6 Pages 1803-1809
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    The optical properties of blue and yellow luminescence have been investigated for Eu 2+ (4f 7 ) ions doped into mixed crystals or solid solutions Sr 1-x Ba _x F 2 (0≤ x ≤1.0), focusing on the thermal relaxation mechanism. The intense blue band observed in Sr-rich crystals exchanges for a yellow one in Ba-rich crystals below 100 K.For varying the mixture ratio, the two bands conserve persistently each quantity of luminescence peak, intensity, half-linewidth, and lifetime.First measurements of the precise lifetime and the thermal activation energy were carried out against the variation of mixture ratio as well as temperature. For the yellow luminescence, it was found that there was a large difference in the decreasing rates between the spectral intensity and the lifetime.A mechanism of energy transfer from blue to yellow luminescence is discussed byapplying the configuration coordinate diagrams.
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  • Jan Gregus, Junji Watanabe, Jun’ichiro Nakahara
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1997 Volume 66 Issue 6 Pages 1810-1815
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Photoluminescence spectra of Mn2+ in CdMnTe are investigated using tunable laser in a temperature range from 15 K to 80 K. The shift of the photoluminescence peak energy with the excitation energy is observed. From analysis using the shift and the photoluminescence width, we obtain the temperature dependencies of homogeneous and inhomogeneous broadening widths of the d-d transition. In addition, the effects of high hydrostatic pressure on the electron-phonon coupling strength and the homogeneous and inhomogeneous widths are investigated.
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  • Makiko Omaru, Shin–ya Takahashi, Akimasa Ohnishi, Takehisa Yoshi ...
    Subject area: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
    1997 Volume 66 Issue 6 Pages 1816-1821
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    From the reflection spectra of SnI4 single crystal, the exciton absorption band has been observed at peak energies, 3.13, eV (1.6, K) and 3.07, eV (room temperature). The binding energy of the exciton is estimated to be 350, meV (1.6, K) assuming the hydrogen-like series for the exciton energy levels. The novel idea of using a cyclodextrin molecule as a size-controlling vessel to make a SnI4 cluster is proposed. The reflection spectra of SnI4 clusters inserted in α -, β - and γ -cyclodextrins were measured. The first exciton absorption peak of the clusters shifts to the higher energy by nearly 0.3, eV (1.6, K) and 0.4, eV (room temperature) compared with that of the single crystals. The shift is due to the quantum size effect.
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  • Dong–Seok Yang, Seong–Cho Yu, Won–Tae Kim, Ikuo Naka ...
    Subject area: Materials science.
    1997 Volume 66 Issue 6 Pages 1822-1824
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Changes in structure and magnetization of Fe80(Y2O3)20 made by the mechanical alloying have been examined by the extended X-ray absorption fine structure (EXAFS) study and the vibrating sample magnetometer (VSM). EXAFS study and temperature dependence of magnetization show that the metastable alloy is the mixture of iron itself and iron-oxide compounds.
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  • Norikazu Goto, Akira Okada, Toshiaki Kakitani, Akira Yoshimori, Yasuyo ...
    Subject area: Physical chemistry.
    1997 Volume 66 Issue 6 Pages 1825-1835
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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    Monte Carlo simulation calculations were made for investigating the structure and the mechanism of the electron transfer reactions at the metal-electrolyte interface. All the particles are assumed to be spherical with the same radii and the metal was treated as a source of the mirror image force. We obtained a result that many electrolyte ions are directly adsorbed to the metal surface in the presence and absence of the external field, indicating that the structure of the interface is non-uniform and a strong alternating local field is produced. Free energy surfaces for the electron transfer reaction are calculated using the simulation data. We found that the distance fluctuation of a reactant from the metal surface makes significant contribution to the free energy surfaces as well as the orientational and positional fluctuations of solvent and electrolyte ions do, and that the distribution of these fluctuations deviate greatly from the Gaussian, bringing about large nonlinear response effects in the relation between the activation free energy and energy gap of the reaction.
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  • Akira Onuki
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 6 Pages 1836-1837
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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  • Yukihiro Okuno, Osamu Narikiyo, Kazumasa Miyake
    Subject area: Lattice dynamics and crystal statistics.
    1997 Volume 66 Issue 6 Pages 1838-1839
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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  • Yoshihiro Kuroiwa, Mao Liu, Trevor R. Finlayson, T. Fred Smith, Kazuyu ...
    Subject area: Lattice dynamics and crystal statistics.
    1997 Volume 66 Issue 6 Pages 1840-1841
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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  • Takao Ebihara, Yoshinori Haga, Etsuji Yamamoto, Yuji Aoki, Hideyuki Sa ...
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 6 Pages 1842-1843
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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  • Yutaka Matsumoto, Minoru Otani, Hiroshi Miyagi, Naoshi Suzuki
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1844-1845
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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  • Ken’ichi Takano, Kazuhiro Sano
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 6 Pages 1846-1847
    Published: June 01, 1997
    Released on J-STAGE: October 01, 1999
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