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Volume 72, Issue 6
Displaying 1-46 of 46 articles from this issue
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Sinpei Noguchi, Takao Ohta2003 Volume 72 Issue 6 Pages 1315-1317
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe phase ordering kinetics in the time-dependent Ginzburg–Landau (TDGL) equation with a global coupling is studied by numerical simulations in two dimensions. For several average values of the order parameter, we evaluate the nonequilibrium scattering functions during domain growth after the system is quenched below the order–disorder transition temperature. The obtained scaling forms are compared with the approximate theory.View full abstractDownload PDF (169K) -
Yasumasa Hasegawa, Mayumi Yakiyama2003 Volume 72 Issue 6 Pages 1318-1321
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA possible mechanism for appearance of the horizontal line nodes in triplet superconductor, Sr2RuO4, is proposed. We consider the interlayer Coulomb interaction, as well as the on-site Coulomb repulsion, between electrons in different bands. In the second order perturbation of the interband interaction, the effective interaction becomes dependent on cos\\fracqz2, resulting in horizontal line nodes.View full abstractDownload PDF (107K) -
Masanori Ichioka, Noriyuki Nakai, Kazushige Machida2003 Volume 72 Issue 6 Pages 1322-1325
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSuperconducting double transition in PrOs4Sb12 is investigated by analyzing the anisotropy of the upper critical field Hc2 in the ab-plane, and the possible pairing state is discussed. When mixing due to gradient coupling is active, the twofold-symmetric component is necessarily induced in the fourfold symmetric phase, leading to the twofold oscillation of Hc2, contrary to the experimental result. To avoid the mixing effect, the weak spin–orbit coupling triplet pairing state is considered as a likely pairing function, where time-reversal symmetry is broken.View full abstractDownload PDF (98K) -
Fumitaka Matsubara, Shin-ichi Endoh, Takanori Sasaki2003 Volume 72 Issue 6 Pages 1326-1329
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe performed a Monte Carlo simulation of magnetic domains in an ultrathin film with surface anisotropy. We found that the out-of-plane spin component Si⊥ forms magnetic domains and that the shape of the domains is closely related to the arrangement of the in-plane spin component Si||. When in-plane magnetization is absent (M||=0), isolated bubble-like domains of Si⊥ appear, whereas stripe domains appear when M||≠0. The bubble-like domains were found in thin films, and the stripe domains were found in thick films.View full abstractDownload PDF (342K) -
Shin-ichi Endoh, Fumitaka Matsubara2003 Volume 72 Issue 6 Pages 1330-1333
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe investigate the random anisotropy effect on the spin structure of an ultrathin magnetic film with several monolayers by means of a Monte Carlo simulation. We find that, as the temperature is increased, the film exhibits a spin reorientation transition from an ordered state with the out-of-plane magnetization to an ordered state with the in-plane magnetization. We reveal that, in a pseudo-gap between the two ordered states, complex domains emerge and both the out-of-plane and the in-plane magnetizations vanish.View full abstractDownload PDF (339K) -
Toru Aonishi, Masato Okada2003 Volume 72 Issue 6 Pages 1334-1337
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe propose a theoretical framework for studying the cooperative behavior of dynamically coupled oscillators (DCOs) that possess dynamical interactions. Then, to clarify synchronization phenomena in networks of interneurons which possess inhibitory interactions, we propose a DCO model with dynamics of interactions that tend to cause 180° phase lags. Employing the approach developed here, we demonstrate that although our model displays synchronization at high frequencies, it does not exhibit synchronization at low frequencies because this dynamical interaction does not cause a phase lag sufficiently large to cancel the effect of the inhibition. We interpret the disappearance of synchronization in our model with decreasing frequency as describing the breakdown of synchronization in the interneuron network of the CA1 area below the critical frequency of 20 Hz.View full abstractDownload PDF (117K) -
Kazuaki Narita2003 Volume 72 Issue 6 Pages 1339-1349
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe propose the deformed sine- and sinh-Gordon equations, and present their particular solutions. We also propose the 1st, 2nd and 3rd deformed Liouville equations and their discrete models, and present their particular solutions and N-kink solution.View full abstractDownload PDF (124K) -
Hang-yu Ruan, Yi-xin Chen2003 Volume 72 Issue 6 Pages 1350-1355
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA methodology is developed which provides a systematic way to find the novel exact solutions of the nonlinear Schrödinger (NLS) model with varying dispersion, nonlinearity, and gain or absorption. Soliton solutions in three kinds of optical fibers represented by coefficient varying NLS equations are studied in detail. Some new exact solutions of optical soliton in these models are reported.View full abstractDownload PDF (230K) -
Yan-ze Peng2003 Volume 72 Issue 6 Pages 1356-1359
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSExact solutions to a new Hamiltonian amplitude equation introduced by Wadati et al. are studied. Periodic wave solutions are obtained by means of the mapping method proposed recently by the author. Under limit conditions, exact solitary wave solution and shock wave solution are recovered, and triangular function periodic wave solutions and singular solitary wave solutions are picked up.View full abstractDownload PDF (71K) -
Hidetsugu Sakaguchi, Boris Malomed2003 Volume 72 Issue 6 Pages 1360-1365
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA one-dimensional model of a dispersive medium with intrinsic loss, compensated by a parametric drive, is proposed. It is a combination of the well-known parametrically driven nonlinear Schrödinger (NLS) and complex cubic Ginzburg–Landau equations, and has various physical applications (in particular, to optical systems). For the case when the zero background is stable, we elaborate an analytical approximation for solitary-pulse (SP) states. The analytical results are found to be in good agreement with numerical findings. Unlike the driven NLS equation, in the present model SPs feature a nontrivial phase structure. Combining the analytical and numerical methods, we identify a stability region for the SP solutions in the model’s parameter space. Generally, the increase of the diffusion and nonlinear-loss parameters, which differ the present model from its driven-NLS counterpart, lead to shrinkage of the stability domain. At one border of the stability region, the SP is destabilized by the Hopf bifurcation, which converts it into a localized breather. Subsequent period doublings make internal vibrations of the breather chaotic. In the case when the zero background is unstable, hence SPs are irrelevant, we construct stationary periodic solutions, for which a very accurate analytical approximation is developed too. Stability of the periodic waves is tested by direct simulations.View full abstractDownload PDF (246K) -
Ning Wang, Miki Wadati2003 Volume 72 Issue 6 Pages 1366-1373
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe \\bar∂-dressing method is extended to noncommutative space-time. It is shown that a noncommutative soliton equation and its Lax operators can be represented in the forms of Moyal product, the operator (functional of creation–annihilation operators) and the kernel function of the operator in coherent state representation (CSR). Noncommutative KP (ncKP) equation is taken as an example to illustrate how to solve a noncommutative soliton equation. It is found that the induced soliton equation in the CSR is different from the matrix KP equation usually considered in articles, but is a new soliton equation of integral operator. It is shown that the solutions of a noncommutative soliton equation (both multi-lump and multi-line solitons) can be reduced to solving a set of c-number linear differential equations.View full abstractDownload PDF (127K) -
Hidekatsu Tsuruda, Hiroyuki Shirahama, Tomoko Sameshima, Kazuhiro Fuku ...2003 Volume 72 Issue 6 Pages 1374-1379
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThis paper describes a chaotic synchronization phenomenon observed experimentally in a five-star-coupled phase-locked loop (PLL) oscillator system. This system consists of five PLLs connected in the shape of a star. The state in this system itinerates between the completely synchronized state, in which all PLL oscillators synchronize, and the disordered state, in which all PLLs oscillate individually, via the partially synchronized state. The time-series of the voltage difference between arbitrary two PLL oscillators shows the on-off intermittency. When such a chaotic itinerancy occurs, the distribution function of the duration time of the completely synchronized state is expressed as a −\\frac32 power law which is quite similar to the distribution function of the laminar duration time in the on-off intermittency.View full abstractDownload PDF (167K) -
Jian-Sheng Wang, Yutaka Okabe2003 Volume 72 Issue 6 Pages 1380-1383
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe compare the performance of extremal optimization (EO), flat-histogram and equal-hit algorithms for finding spin–glass ground states. The first-passage-times to a ground state are computed. At optimal parameter of τ=1.15, EO outperforms other methods for small system sizes, but equal-hit algorithm is competitive to EO, particularly for large systems. Flat-histogram and equal-hit algorithms offer additional advantage that they can be used for equilibrium thermodynamic calculations. We also propose a method to turn EO into a useful algorithm for equilibrium calculations.View full abstractDownload PDF (88K) -
Miho Ito, Machiko Izui, Yoshihiro Yamazaki, Mitsugu Matsushita2003 Volume 72 Issue 6 Pages 1384-1389
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSMorphological diagram with respect to crystal growth of L-ascorbic acid (C6H8O6; so-called vitamin C) from methanol solution on a flat glass dish is presented. Varying humidity and initial concentration of L-ascorbic acid in methanol solution, the following three distinct kinds of growing patterns have been observed: homogeneous disk, concentric ring and dendrite. In addition, in higher concentration clearly faceted small single crystals grow in any humidity less than 90%. Crossovers from one pattern to another were observed, too.View full abstractDownload PDF (390K) -
Akiko Ugawa, Osamu Sano2003 Volume 72 Issue 6 Pages 1390-1395
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSAn experimental study is performed on quasi-two dimensional waves in a thin granular layer of thickness h induced by vertical vibration with frequency f and amplitude a under atmospheric pressure. We used sesame of oval shape as well as different sizes of spherical glass and aluminum beads. Irrespective of the container size L, “ripples” are observed in a thin layer which consists of spherical beads (aluminum and glass beads) for relatively small acceleration of external forcing. On the other hand “undulations” are observed in a thicker layer, which consists of sesame as well as spherical beads, for larger accelerations. In the latter, several eigen modes are observed, which is reminiscent of the buckling and bending waves in an elastic rod. Continuum model is shown to explain the observed modes. In addition to acceleration amplitude (2πf)2a⁄g (g: acceleration of gravity) and normalized frequency f\\sqrth⁄g, layer height h⁄d (d: particle size) and aspect ratio L⁄h play important roles.View full abstractDownload PDF (235K) -
Shigeki Matsunaga2003 Volume 72 Issue 6 Pages 1396-1402
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSStructural properties of liquid and superionic phase of Ag3SI are investigated by molecular dynamics simulation (MD), using the Vashishta–Rahman (VR) type potentials. The description of the pair distribution functions obtained by MD in superionic phase is in good agreement with recent neutron diffraction experiments. The features of the bond–angle distributions are obtained to confirm the structure of anions and the positions where cations prefer to reside in the lattice. The peaks of the bond–angle distributions including cations are mainly due to Ag ions at tetrahedral 12(d) sites. At molten phase, the pair distribution functions and bond–angle distributions are rather different from those in super-ionic phase, because they are distorted by thermal disturbance.View full abstractDownload PDF (275K) -
Makoto Yoneya, Isa Nishiyama, Hiroshi Yokoyama2003 Volume 72 Issue 6 Pages 1403-1405
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSpontaneous optical resolution in a racemic β-Me-TFMHPOBC molecule system was investigated with atomistic molecular dynamics (MD) simulations. Conformer distributions obtained from the MD simulations were characterized by two distinct peaks which correspond to the two oppositely directed bent conformers for each (R,S) and (S,R) enantiomer. The local enantio excess was calculated to see progression of the optical resolution from the random enantiomer distributions. In the MD simulations, however, no sign of the resolution was detected.View full abstractDownload PDF (248K) -
Mongi Amami, Abdelhamid ben Salah2003 Volume 72 Issue 6 Pages 1406-1410
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe crystal structure of [N(CH3)4]2HgCl4 has been studied by single crystal X-ray diffraction. the structure is orthorhombic Pnma with lattice parameters 12.419(7), b=9.068(4), and c=15.684(2) Å at room temperature. Each TMA cation disorderly occupies two orientations (TMA is tetramethylammonium). Refinements using restrictions of the non-crystallographic tetrahedral point group for the TMA cations and refinements without restrictions are used to show that TMA has tetrahedral symmetry at all temperatures. The HgCl4 anions are distorted, but the distortions are independent of the temperature.View full abstractDownload PDF (382K) -
Kenichi Oikawa, Takashi Kamiyama, Hisato Kato, Yoshinori Tokura2003 Volume 72 Issue 6 Pages 1411-1417
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe crystal and magnetic structures of an ordered double perovskite, Ca2FeReO6, were studied by high-resolution neutron powder diffraction as a function of the temperature from 7 K to 550 K. All of the diffraction data were precisely refined by the Rietveld method, and we confirmed a structural phase transition at around 140 K where the metal–insulator transition occurs from ferrimagnetic metal (FM) to ferrimagnetic insulator (FI) phases. At this temperature, there exists a change in the distortion direction of [ReO6] octahedra together with a spin reorientation, which strongly supports the occurrence of orbital ordering of the t2g electrons. FM and FI phases coexist in a narrow temperature range at around 140 K, which is typically seen in the first-order phase transition. A phase separation was not detected in our well-characterized sample.View full abstractDownload PDF (354K) -
Jun Suda, Osamu Kamishima, Kohhei Hamaoka, Ichirou Matsubara, Takeshi ...2003 Volume 72 Issue 6 Pages 1418-1422
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe phonon-dispersion curves of the YAlO3 crystal are calculated on the basis of a rigid-ion model using the measured frequency values by Raman and infrared polarized spectroscopy at room temperature. The temperature dependence of the molar heat capacity of YAlO3 is also calculated using the one-phonon density of states obtained from the phonon-dispersion curves. The first-order polarized Raman spectra of A1g mode in the YAlO3 crystal have been measured in the temperature range between 77 and 473 K. The temperature dependence for the linewidth of the A1g modes has been analyzed at 152, 350 and 550 cm−1 using the phonon-dispersion curves, and the calculated result reproduces with the observed one in the temperature range of 77–500 K. Thus, the temperature dependence of linewidth of the A1g modes in YAlO3 crystal is approximately explained by the cubic anharmonic term in the expansion series of the crystal potential energy.View full abstractDownload PDF (379K) -
Daniil G. Sannikov, Hiroyuki Mashiyama2003 Volume 72 Issue 6 Pages 1423-1425
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSTheoretical phase diagrams for {N(CH3)4}4ZnI4 crystal are constructed using the phenomenological approach, which was developed earlier for {N(CH3)4}4MCl4 family crystals. On these diagrams, as well as on the experimental diagram, there are three commensurate phases and there is no incommensurate phase. To explain this the phase transition from the initial phase to the phase with q=1⁄2 is considered to be first order. The theoretical temperature–pressure phase diagram is plotted and is found to be in agreement with the experimental diagram. The approximations and assumptions made in the construction of theoretical diagrams are discussed.View full abstractDownload PDF (76K) -
Hideshi Fujishita, Yuya Ishikawa, Sounosuke Tanaka, Akira Ogawaguchi, ...2003 Volume 72 Issue 6 Pages 1426-1435
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSX-ray and neutron diffraction and dielectric measurements were performed for the antiferroelectric phase of PbZrO3. The antiferroelectric Σ3(TO) and the R25 superlattice-reflection intensities, and the pseudo-tetragonal lattice distortion of the perovskite sublattice showed the same temperature dependence below room temperature, showing a saturation below about 60 K. Above room temperature, however, they showed rather different temperature dependences. These temperature dependences can be well described by the free energy based on a group theoretical method, which includes a quantum effect. The atomic shifts do not necessarily conform to a simple concept of order parameter in soft mode condensation. However the antiferroelectric phase transition can be understood by the phenomenological theory for coupled order parameters if applied over the whole temperature region.View full abstractDownload PDF (286K) -
Akira Furukawa2003 Volume 72 Issue 6 Pages 1436-1445
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSRecently, a systematic experiment measuring critical anomaly of viscosity of polymer solutions has been reported by Tanaka et al. [Phys. Rev. E 65 (2002) 021802]. According to their experiments, the dynamic critical exponent of viscosity yc drastically decreases with increasing the molecular weight. In this article the kinetic coefficients renormalized by the non-linear hydrodynamic interaction are calculated by the mode coupling theory. We predict that the critical divergence of viscosity should be suppressed with increasing the molecular weight. The diffusion constant and the dynamic structure factor are also calculated. The present results explicitly show that the critical dynamics of polymer solutions should be affected by an extra spatio-temporal scale intrinsic to polymer solutions, and are consistent with the experiment of Tanaka et al.View full abstractDownload PDF (360K) -
Dai S. Hirashima, Tsutomu Momoi, Takeo Takagi2003 Volume 72 Issue 6 Pages 1446-1451
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSPhase diagram of quantum particles adsorbed on a periodic substrate is studied by means of the path integral Monte Carlo method. Interaction potential between particles is assumed to be a hardcore-like (r−12-potential) one or the Lennard–Jones potential. The density is fixed to a commensurate one. When the hardcore diameter is large, the system solidifies from a gas phase at a finite temperature. By changing the mass of particles, the magnitude of the zero point motion is changed. It is found that the system solidifies at a higher temperature as the mass becomes lighter, i.e., the zero point motion promotes the solidification of particles.View full abstractDownload PDF (143K) -
Akira Inagaki, Shin’ichi Katayama2003 Volume 72 Issue 6 Pages 1452-1457
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe binding energy of quasi-two-dimensional electron–hole liquid (EHL) at zero temperature is calculated for type-II (GaAs)m/(AlAs)m (5≤m≤13) quantum wells (QWs). The correlation energy is evaluated by adopting a random phase approximation of Hubbard. For comparison, we calculate the binding energy of EHL for type-I (GaAs)m/(AlAs)m (14≤m≤20) QWs. It is demonstrated that the EHL in type-II GaAs/AlAs QWs is more stable state than exciton and biexciton at high excitation density, while the EHL is unstable in type-I GaAs/AlAs QWs.View full abstractDownload PDF (132K) -
Muneo Sugiura, Yoshikazu Suzumura2003 Volume 72 Issue 6 Pages 1458-1468
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe effect of the charge ordering on the spin–Peierls (SP) state has been examined by using a Peierls–Hubbard model at quarter-filling with dimerization, on-site and nearest-neighbor repulsive interactions. By taking account of the presence of dimerization, a bond distortion is calculated variationally with the renormalization group method based on bosonization. When the charge ordering appears at V=Vc with increasing the nearest-neighbor interaction (V), the distortion exhibits a maximum due to competition between the dimerization and the charge ordering. It is shown that the second-order phase transition occurs from the SP state with the bond alternation to a mixed state with an additional component of the site alternation at V=Vc.View full abstractDownload PDF (354K) -
Takehiko Mori2003 Volume 72 Issue 6 Pages 1469-1475
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSPhase diagrams of charge order patterns of the θ-phase organic conductors are investigated on the basis of the static-limit extended Hubbard model including the second nearest Coulomb repulsion V′. Since the θ-phase is close to the triangular lattice rather than the square lattice, a 3-fold non-stripe charge order is stable in a considerably large region between the stripe phases and the uniform phase. At finite temperatures, such unevenly ordered patterns as the 3-fold phase D+D21⁄4+ become more stable than the evenly ordered stripes, D+D0, and it is unlikely that the stripe phase directly transforms to the uniform phase. These results suggest the existence of an unevenly ordered pattern in the metallic state of θ-(BEDT-TTF)2RbM(SCN)4 [BEDT-TTF: bis(ethyleneditho)tetrathiafulvalene, M = Zn and Co] above TMI=190 K, accounting for the observation of modulated structures in the X-ray measurement, broadening of the NMR line, flat temperature dependence of the resistivity, and the first-order character of the 190 K transition.View full abstractDownload PDF (171K) -
Maki Tokii, Shinya Wakoh2003 Volume 72 Issue 6 Pages 1476-1482
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSOver these two decades, the local density functional approximation (LDA) has been used as an effective potential for various band calculations and has obtained many fruitful results. Recently, however, LDA+U method came to be used to obtain better results by choosing a suitable value of U. There have been a few versions of the method. In this paper another new version of the LDA+U method, i.e. U(1.0−⟨nm⟩), is proposed and a suitable effective potential of metallic V and Cr is obtained by the value of U=0.15Ry=2eV.View full abstractDownload PDF (161K) -
Yasuhiko Takahashi, Junji Akimoto, Yoshito Gotoh, Kaoru Dokko, Matsuhi ...2003 Volume 72 Issue 6 Pages 1483-1490
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSingle crystals of LiMn2O4 and LiMnO2 have been successfully synthesized by a flux method. The lithium-ion deintercalated λ-MnO2 single crystal has been prepared electrochemically using a microelectrode-based system. The single-crystal X-ray diffraction study at room temperature confirmed the cubic spinel Fd\\bar3m space group for LiMn2O4 and λ-MnO2, and the orthorhombic Pmnm space group for LiMnO2, respectively. The crystal structure of LiMn2O4 was refined using two models. A new oxygen displacement model with 1/3 occupation at the 96g site gives better reliable values R=1.70% and wR=1.49% for 213 independent reflections. The crystal structure of LiMnO2 has been refined to the reliable values R=1.32% and wR=1.45% for 676 independent reflections. In order to understand chemical bonding nature of these materials, we performed to analyze the electron density distributions by Maximum Entropy Method (MEM) using the single-crystal X-ray diffraction data. From the results of MEM analysis, the strong covalent bonding features were found between the Mn and O atoms in these manganese oxides. We also calculated electron density in LiMn2O4 and LiMnO2 by the full-potential linearized augmented-plane-wave (FLAPW) method. The electron density distribution features obtained theoretically were in good agreement with the experimental observations. A combined analysis of the MEM and FLAPW calculations clearly indicated that the covalent bonding observed between the Mn and O atoms in LiMn2O4 is mainly assigned to the Mn-3d and O-2p hybridization which locates in the energy range of −7.5<E<−2.5 eV.View full abstractDownload PDF (410K) -
Taketomo Kageyama, Natsuki Aito, Satoshi Iikubo, Masatoshi Sato2003 Volume 72 Issue 6 Pages 1491-1494
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe anomalous Hall coefficient Rs has been studied for the reentrant spin glass system Fe0.7Al0.3 by measuring the magnetization M and the Hall resistivity ρH. We have found that Rs exhibits anomalous change of the temperature dependence at the spin–glass transition temperature TG, indicating that an additional term appears along with the beginning of the spin glass phase. The result is discussed in relation to the recent proposal of the chirality mechanism of the Hall effect in the spin glass phase.View full abstractDownload PDF (179K) -
Tomoki Tasai, Mikio Eto2003 Volume 72 Issue 6 Pages 1495-1500
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe theoretically examine the effects of polaron formation in quantum dots on the transport properties. When a separation between two electron-levels in a quantum dot matches the energy of the longitudinal optical (LO) phonons, the polarons are strongly formed. The Rabi splitting between the levels is observable in a peak structure of the differential conductance G as a function of the bias voltage. The polaron formation suppresses the peak height of G, which is due to the competition between the resonant tunneling (resonance between a level in the dot and states in the leads) and the polaron formation (Rabi oscillation between two levels in the dot). G shows a sharp dip at the midpoint between the split peaks. This is attributable to the destructive interference between bonding and anti-bonding states in a composite system of electrons and phonons.View full abstractDownload PDF (636K) -
Kyu Ueno, Mikio Eto2003 Volume 72 Issue 6 Pages 1501-1509
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSElectric transport through atomic-size point contacts of magnetic metals is theoretically studied. The conductance in spin-polarized states is examined, using a Green’s function method to take into account the electron–electron interaction. In a single s-band model, the conductance quantization is observed in units of e2⁄h per spin direction. In a two-band model (broad s and narrow s bands), the conductance is considerably suppressed by the interband scattering around the point contact when the spin is polarized in one direction in the whole system. When the spin polarization on one side of the contact is anti-parallel to that on the other side, the interband scattering is not relevant and the conductance is quantized. These calculated results are in accordance with experimental results for break-junctions of Ni.View full abstractDownload PDF (254K) -
Susumu Okada, Atsushi Oshiyama2003 Volume 72 Issue 6 Pages 1510-1515
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report first-principle total-energy electronic-structure calculations in the density functional theory performed for zigzag carbon nanotubes with finite length. We find that the electronic structure of the finite-length nanotubes exhibits certain magnetic ordering. Detailed analyses of energy levels and spin densities unequivocally reveal nature of the magnetic ordering which is associated with the peculiar edge-localized states of the graphite flakes. The magnetic ordering of the finite-length nanotube strongly depends on its radius and length.View full abstractDownload PDF (355K) -
Takashi Tayama, Toshiro Sakakibara, Hitoshi Sugawara, Yuji Aoki, Hidey ...2003 Volume 72 Issue 6 Pages 1516-1522
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe investigated the magnetic phase diagram of the first Pr-based heavy fermion superconductor PrOs4Sb12 by means of high-resolution dc magnetization measurements in low temperatures down to 0.06 K. The temperature dependence of the magnetization M(T) at 0.1 kOe exhibits two distinct anomalies at Tc1=1.83 K and Tc2=1.65 K, in agreement with the specific heat measurements at zero field. Increasing magnetic field H, both Tc1(H) and Tc2(H) move toward lower temperatures without showing a tendency of intersecting to each other. Above 10 kOe, the transition at Tc2(H) appears to merge into a line of the peak effect which is observed near the upper critical field Hc2 in the isothermal M(H) curves, suggesting a common origin for these two phenomena. The presence of the field-induced ordered phase (called phase A here) is confirmed for three principal directions above 40 kOe, with the anisotropic A-phase transition temperature TA: TA[100]>TA[111]>TA[110]. The present results are discussed on the basis of crystalline-electrical-field level schemes with a non-magnetic ground state, with emphasis on a Γ1 singlet as the possible ground state of Pr3+ in PrOs4Sb12.View full abstractDownload PDF (779K) -
Koichi Hiraoka, Saburo Kashiba, Shoichi Tomiyoshi2003 Volume 72 Issue 6 Pages 1523-1527
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have measured zero field 59Co NMR, X-ray diffraction (XRD) and magnetization in ferromagnetic mechanically alloyed Co75Ti25 powder as a function of milling time at 4.2 K. The XRD patterns showed that the sample is primarily in an amorphous phase after a short milling time of 10 h, and no clear amorphous–crystalline phase transformation is detected with further milling. The NMR results revealed that successive phase transformations occur with milling, and the amorphous phase consists of small clusters of such ferromagnetic phases as fcc-Co3Ti, hexagonal-Co2Ti, bcc-Co3Ti, fcc-Co and fcc-Co–Ti solid solution depending on the milling time. The bcc-Co3Ti phase, being metastable, is a disordered one in contrast to the ordered fcc-Co3Ti phase and has a Co magnetic moment larger than that of fcc-Co3Ti. We suggest that the precipitation of Co plays an important role in the cyclic phase transformation, which was previously reported.View full abstractDownload PDF (109K) -
Shin-ichiro Kondo, Kosaku Yamada2003 Volume 72 Issue 6 Pages 1528-1533
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have theoretically examined whether magnetic moment of 3d impurity such as Fe or Co can be induced or not in magnetic dilute alloy when atoms with high electronegativity such as halogen or oxygen ones are doped into nonmagnetic matrix. Based on the impurity Anderson model, we have analyzed the magnetic state in magnetic dilute alloys, considering that the effect of doping atoms can be regarded as the impurity potential. Using the mean field approximation, we evaluate the green function for d electrons. Through the self-consistent calculation with respect to the number of d electrons with spin ↑ or ↓, it is disclosed that, although the initial state is non-magnetic, a magnetic moment can be induced by an impurity potential caused by doping atoms. In particular, when doped atoms have large electronegativity and/or there exists a strong Coulomb repulsive interaction between conduction electrons and doped atoms, magnetic moment is found to be easily induced from non-magnetic state.View full abstractDownload PDF (115K) -
Osamu Sakai, Ryousuke Shiina, Hiroyuki Shiba2003 Volume 72 Issue 6 Pages 1534-1543
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe invariant interaction form between multipoles, including the octupoles, is studied for three types of cubic lattices: s.c., b.c.c. and f.c.c. The coupling terms can be arranged in a form similar to the hopping matrices between LCAO’s. By using it, order parameters in the magnetic field are classified into groups in which they couple with each other, and the symmetry of the antiferro-quadrupolar (AFQ) moment is analyzed through induced antiferromagnetic moments (AFM). In this way the table for s.c. by Shiina et al. [J. Phys. Soc. Jpn. 66 (1997) 1741] is generalized for general wave vectors of the three lattice types. Recent experimental results of TmTe having the f.c.c. structure are analyzed from this viewpoint. The nature of the ferromagnetic moment below the AFM transition in the AFQ phase is also discussed. Finally brief comments are given also on field-induced moments in PrFe4P12 and NpO2.View full abstractDownload PDF (149K) -
Y. J. Wang, Y. J. Kim, R. J. Christianson, S. C. LaMarra, F. C. Chou, ...2003 Volume 72 Issue 6 Pages 1544-1553
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report comprehensive synchrotron x-ray scattering and magnetic susceptibility studies of the doped spin–Peierls materials Cu1−xZnxGeO3 and CuGe1−ySiyO3. Temperature versus dopant concentration phase diagrams are mapped out for both Zn and Si dopants. The phase diagrams of both Cu1−xZnxGeO3 and CuGe1−ySiyO3 closely resemble that of Cu1−xMgxGeO3, including the observation that the spin gap is established at a much higher temperature than the temperature at which the spin–Peierls dimerization attains long-range order. The spin–Peierls transitions in doped samples exhibit unusual phase transition behavior, characterized by highly rounded phase transitions, Lorentzian squared lineshapes, and very long relaxation times. Phenomenological explanations for these observations are given by considering the effects of competing random bond interactions as well as random fields generated by the dopants. We have also confirmed the reentrance of the spin–Peierls phase when the temperature is lowered through the antiferromagnetic ordering transition. The low temperature re-entrance of the spin–Peierls phase has been explained speculatively using a local phase separation scheme between the spin–Peierls phase and the Néel phase.View full abstractDownload PDF (506K) -
Toku Ishibashi, Mitsuo Machida2003 Volume 72 Issue 6 Pages 1554-1559
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe motions of the phosphite anions and glycinium cations in H3NCH2COOH·H2PO3 (GPI) and its deuterated analogue (DGPI) were investigated by 1H, 13C and 31P spin–lattice relaxation times T1. For both GPI and DPGI, T1’s of the 1H, 13C and 31P nuclei reflect the amino rotation, methylene libration and motion of the phosphite anions, respectively. Activation energies obtained from T1’s of 1H, 13C and 31P nuclei are 28.6(2), 26.0(4) and 26.2(4) kJ/mol for GPI and are 34.9(6), 27(1), 47(2) kJ/mol for DGPI, respectively. The deuterium substitution increases Ea for the motion influenced by the hydrogen bonding. In all the observed motions, correlation times of DGPI are larger than those of GPI.View full abstractDownload PDF (119K) -
Hironobu Shoji, Munetaka Taguchi, Eiju Hirai, Toshiaki Iwazumi, Akio K ...2003 Volume 72 Issue 6 Pages 1560-1569
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe study the incident, the scattering and the azimuthal angle dependences of the Mn Kβ resonant x-ray emission spectroscopy (RXES) due to the electric quadrupole excitation by tuning the incident photon energy to the pre-edge region of the Mn K-edge for a MnO single crystal both experimentally and theoretically. RXES caused by the electric quadrupole excitation shows a strong sensitivity to these angles, and the agreement between theory and experiment is good. Different angle dependences are shown between the excitation to the T2g orbital and that to the Eg one. It is discussed that RXES can be a powerful tool to separate the electric quadrupole and dipole contributions in the pre-edge region of the transition-metal K-edge in transition metal compounds.View full abstractDownload PDF (222K) -
Tadahiko Harami, Mariko Kataoka2003 Volume 72 Issue 6 Pages 1570-1573
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThermal stability of V centers has been investigated at room temperature (RT) for additively colored alkali-iodide crystals by means of optical absorption measurements. V2 and V3 bands due to V centers in the crystal were gradually bleached by annealing at temperatures near RT. The bleaching rate of the bands is proportional to the square of the V-center concentration. The activation energies for bleaching of the V bands in KI and RbI crystals are estimated from the bleaching rates to be 0.85±0.04 eV and 0.82±0.03 eV, respectively. The V2 bands in the crystals containing divalent cations bleach only weakly at RT. The effect of impurities, such as divalent cations, on the thermal stability of the V centers will be discussed.View full abstractDownload PDF (97K) -
Sheng Wang, Ke-Qin Zhang, Qing-Yu Xu, Mu Wang, Ru-Wen Peng, Ze Zhang, ...2003 Volume 72 Issue 6 Pages 1574-1580
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSIn this article we report the systematic studies on the oscillation of contrast in front of a growing zinc dendrite in electrochemical deposition observed with interference contrast microscopy. The dependence of the oscillation frequency on the experimental conditions, such as the electric current, the resistance of ion transfer, pH of the electrolyte and the tilting of the electrodeposition cell, etc., has been investigated. The microstructures of the electrodeposits are analyzed with transmission electron microscopy. We conclude that the contrast oscillation in front of the zinc deposit is indeed associated with the concentration oscillation, and is synchronized with the electric voltage/current signals. Although the oscillation can be affected by mass transport in the system, we suggest that it roots from the alternating deposition of zinc and zinc hydroxide on the deposit–electrolyte interface.View full abstractDownload PDF (285K) -
Akira Takahashi, Yoshiro Nakata, Toshiharu Takizawa2003 Volume 72 Issue 6 Pages 1581-1589
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe found two doublet signals A and B in 2D-NMR of dipalmitoyl-phosphatidylcholine–D2O system at a low water content below the temperature of the onset of the main phase transition, i.e. in the β′-crystalline (Lβ′) phase. The splitting of each doublet becomes minimum at the onset of the transition. The signal A decreases in intensity with a slight increase of its splitting as the temperature increases further, accompanying the marked growth of the signal B in its intensity and splitting. These features of two doublets in the Lβ′ phase and at higher temperatures have never been noticed. The signals A and B were ascribed to the tightly bound water and the loosely bound water, respectively. These assignments were confirmed by the theoretical calculations of the splitting of the doublet A for all possible number of the tightly bound water molecules.View full abstractDownload PDF (266K) -
Yukihiko Yoshida, Yasumitsu Matsuo, Seiichiro Ikehata2003 Volume 72 Issue 6 Pages 1590-1591
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (82K) -
Jong-Ho Park, Chung-Sik Kim, Byung-Chun Choi, Byung Kee Moon, Hyo-Jin ...2003 Volume 72 Issue 6 Pages 1592-1593
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (76K) -
2003 Volume 72 Issue 6 Pages 1594
Published: June 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (23K)
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