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- Proceedings of the Physico-Mathematical Society of Japan. 3rd Series
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- Tokyo Sugaku-Butsurigakukwai Kiji-Gaiyo
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Volume 72, Issue 10
Displaying 1-50 of 51 articles from this issue
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Tota Nakamura, Yoshiyuki Ito2003 Volume 72 Issue 10 Pages 2405-2408
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe propose a new quantum Monte Carlo algorithm that realizes a relaxation intrinsic to an original quantum system. The Monte Carlo dynamics satisfies the dynamic scaling relation τ∼ξz and is independent of the Trotter number. The finiteness of the Trotter number appears as the finite-size effect. An infinite Trotter number version of the algorithm, which enables us to observe a true relaxation of the original system, is also formulated. The strategy of the algorithm is a compromise between a conventional worldline local flip and a modern cluster loop flip. It is a local flip in the real-space direction and is a cluster flip in the Trotter direction. The new algorithm is tested using the transverse-field Ising model in two dimensions. An accurate phase diagram is obtained.View full abstractDownload PDF (130K) -
Osamu Moriyama, Hiroto Itoh, Satoru Matsushita, Mitsugu Matsushita2003 Volume 72 Issue 10 Pages 2409-2412
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSLong tails of the duration distributions for disabilities in the aged are analyzed. Log–normal distribution shows excellent fit with various data on the durations of disabilities, irrespective of their severity. Persisting long tails suggest the fractal nature of disability distributions. For approximately 60% of the patients, the duration distributions are also mimicked by the first passage time distribution (FPTD) of one-dimensional Brownian motion. The finding that the data fit the log–normal distribution very well and FPTD fairly well reveals disability for the aged to be a stochastic process of suffering successively from various endogenous diseases, i.e., multiple pathology.View full abstractDownload PDF (200K) -
Wilson Agerico Diño, Rifki Muhida, Hiroshi Nakanishi, Hideaki K ...2003 Volume 72 Issue 10 Pages 2413-2416
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSHere we consider a nanoscale material consisting of two Fe atoms sitting on a planar C10 cluster. On the basis of the density functional theory (DFT), we demonstrate how it is feasible to induce spin polarization on an initially nonmagnetic carbon material by introducing magnetic adsorbates, and how the presence of hydrogen reduces the induced polarization.View full abstractDownload PDF (171K) -
Fuyuki Shimojo, Kozo Hoshino, Y. Zempo2003 Volume 72 Issue 10 Pages 2417-2420
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe bonding properties of liquid Te are investigated by means of ab initio molecular-dynamics simulations as a function of pressure. We discuss the pressure dependence of electronic states around each Te atom in connection with the anomalous structural change of liquid chalcogenides under pressure. It is demonstrated that maximally localized Wannier functions are highly useful for investigating the electronic properties of the liquids consisting of covalently bonded atoms.View full abstractDownload PDF (369K) -
Mamoru Yamashita2003 Volume 72 Issue 10 Pages 2421-2424
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSPhase transitions of freely suspended chiral smectic films exhibiting a first order phase transition in a bulk system are studied in the framework of a phenomenological theory, in which such a widely observed finding that the surface layer orders at a temperature higher than the bulk critical temperature is taken into account. While the inner portion of the film exhibits the first order phase transition at a temperature below that of the surface layer in the system of sufficient thickness, a continuous change occurs for the system with a thickness smaller than a critical thickness. The mechanism of the continuous change is elucidated on the basis of the phase diagram of the bulk system on the field versus temperature plane, where nonuniformity due to the ordered surface layers is replaced by an effective field and the high-temperature phase is connected continuously to the low-temperature one by the insertion of an unstable state between them.View full abstractDownload PDF (115K) -
Yasumasa Takagi, Yoshihide Yoshimoto, Kan Nakatsuji, Fumio Komori2003 Volume 72 Issue 10 Pages 2425-2428
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe reconstruction on a Ge(001) surface is locally and reversibly changed between c(4×2) and p(2×2) by controlling the bias voltage of a scanning tunneling microscope (STM) at 80 K. It is c(4×2) with the sample bias voltage Vb≤−0.7 V. This structure can be maintained with Vb≤0.6 V. When Vb is higher than 0.8 V during the scanning, the structure changes to p(2×2). This structure is then maintained with Vb≥−0.6 V. The observed local change of the reconstruction with hysteresis is attributed to the energy transfer process from the tunneling electron to the Ge lattice in the electric field under the STM tip.View full abstractDownload PDF (226K) -
Takeo Hoshi, Takeo Fujiwara2003 Volume 72 Issue 10 Pages 2429-2432
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA hybrid scheme between large-scale electronic structure calculations is developed and applied to nanocrystalline silicon with more than 105 atoms. Dynamical fracture processes are simulated under external loads in the [001] direction. We show how the fracture propagates anisotropically on the (001) plane and reconstructed surfaces appear with asymmetric dimers. Step structures are formed in larger systems, which is explained by the beginning of a crossover between nanoscale and macroscale samples.View full abstractDownload PDF (513K) -
Arata Tanaka2003 Volume 72 Issue 10 Pages 2433-2436
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe metal–insulator transition in VO2 was investigated using the three-band Hubbard model, in which the degeneracy of the 3d orbitals, the on-site Coulomb and exchange interactions, and the effects of lattice distortion were considered. A new scenario on the phase transition is proposed, where the increase in energy level separation among the t2g orbitals caused by the lattice distortion triggers an abrupt change in the electronic configuration in doubly occupied sites from an S=1 Hund’s coupling state to a spin S=0 state with much larger energy, and this strongly suppresses the charge fluctuation. Although the material is expected to be a Mott–Hubbard insulator in the insulating phase, the metal-to-insulator transition is not caused by an increase in relative strength of the Coulomb interaction against the electron hopping as in the usual Mott transition, but by the level splitting among the t2g orbitals against the on-site exchange interaction. The metal–insulator transition in Ti2O3 can also be explained by the same scenario. Such a large change in the 3d orbital occupation at the phase transition can be detected by linear dichroic V 2p x-ray absorption measurements.View full abstractDownload PDF (537K) -
Takashi Koretsune, Masao Ogata2003 Volume 72 Issue 10 Pages 2437-2440
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe two-dimensional t–J model of the triangular and kagomé lattice is studied by high temperature expansions. The analyses of uniform susceptibility as well as the ground-state energy show strong evidence that ferromagnetic ground state exists in a wide region in the phase diagram with respect to electron density, n, and superexchange coupling, J, which is a different feature from the case of the square lattice. This result means that the low-density region, where the ferromagnetism is understood by Kanamori’s mechanism, continues to Nagaoka’s ferromagnetism in frustrated lattices. We also find the possibility of partial ferromagnetism in the low-density region of the triangular lattice.View full abstractDownload PDF (106K) -
Eiji Kaneshita, Masanori Ichioka, Kazushige Machida2003 Volume 72 Issue 10 Pages 2441-2444
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSpectral weight is investigated for the metallic diagonal stripe state in a two-dimensional Hubbard model, and the Fermi arc observed by the angle-resolved photoemission spectroscopy of La2−xSrxCuO4 is discussed. The Fermi arc coming from the midgap state of a diagonal stripe appears near (\\fracπ2,\\fracπ2) and at the equivalent positions in the reciprocal space, and the gap opens below the midgap state. We show how this spectral weight structure depends on the phasing of stripes, i.e., site- or bond-centered stripes.View full abstractDownload PDF (105K) -
Shigeki Onoda, Naoto Nagaosa2003 Volume 72 Issue 10 Pages 2445-2448
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSInterplay between Mott transition and the multicritical phenomenon of d-wave superconductivity (SC) and antiferromagnetism (AF) is studied theoretically. We describe the Mott transition, which is analogous to a liquid–gas phase transition, in terms of an Ising-type order parameter η. We reveal possible mean-field phase diagrams produced by this interplay. Renormalization group analysis up to one-loop order gives flows of coupling constants, which in most cases lead to fluctuation-induced first-order phase transitions even when the SO(5) symmetry exists betwen the SC and AF. Behaviors of various physical quantities around the Mott critical point are predicted. Experiments on κ-(BEDT-TTF)2X are discussed from this viewpoint.View full abstractDownload PDF (220K) -
Hirono Fukazawa, Kosaku Yamada2003 Volume 72 Issue 10 Pages 2449-2452
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSOn the basis of a three-dimensional Hubbard model, the superconducting mechanism of CeIn3 under high pressure is investigated by the third-order perturbation theory with respect to the on-site Coulomb interaction U. Here we propose the d-wave pairing state induced by antiferromagnetic spin fluctuations. The estimated superconducting transition temperature is lower by one order than that in the two-dimensional system for the same value of U⁄W (W = bandwidth). This result is consistent with the difference between CeIn3 and CeRhIn5.View full abstractDownload PDF (159K) -
Yoshiaki Kobayashi, Mai Yokoi, Masatoshi Sato2003 Volume 72 Issue 10 Pages 2453-2455
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSLayered Co oxide NaxCoO2·yH2O with the superconducting transition temperature Tc=4.5 K has been studied by 59Co-NMR. The Knight shift K estimated from the observed spectra of a powder sample exhibits almost temperature (T)-independent behavior above Tc and decreases with decreasing T below Tc. This result and the existence of the coherence peak in the spin–lattice relaxation rate versus T curve reported by the present authors indicate, naively speaking, that the singlet order parameter with s-wave symmetry is realized in NaxCoO2·yH2O. Differences in the observed behaviors between the spectra of a nonaligned sample and those of an aligned sample embedded in epoxy adhesive by applying an external magnetic field are discussed.View full abstractDownload PDF (170K) -
Yasumasa Hasegawa2003 Volume 72 Issue 10 Pages 2456-2459
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDipole interaction in triplet superconductivity is studied. If Cooper pairs are formed by electrons at r and r+(±\\fraca2,±\\fraca2,±\\fracc2) in a body-centered tetragonal lattice (in this case line nodes run horizontally on a cylindrical Fermi surface), the dipole energy is low when the d-vector is perpendicular to the direction of the angular momentum of the Cooper pairs (l-vector). This result is in contrast with the dipole energies in the Anderson–Brinkman–Morel (ABM) state of superfluid 3He, where the d-vector is forced to be parallel or antiparallel to the l-vector by dipole interaction. The recent NQR experiment in Sr2RuO4 by Ishida et al. can be explained by this result.View full abstractDownload PDF (91K) -
Hiroto Adachi, Shigeru Koikegami, Ryusuke Ikeda2003 Volume 72 Issue 10 Pages 2460-2463
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSBased on a theoretical argument and Monte Carlo simulations of a Ginzburg–Landau model derived microscopically, it is argued that, in type-II superconductors where both the paramagnetic and orbital depairings are important, a strong first-order transition (FOT) at Hc2 expected in the mean field (MF) approximation never occurs in real systems and changes due to the fluctuation into a crossover. The present result explains why a nearly discontinuous crossover at Hc2 with no intrinsic hysteresis is observed only in a clean superconducting material with a singlet pairing and a high condensation energy such as CeCoIn5.View full abstractDownload PDF (126K) -
Hitoshi Ohta, Susumu Okubo, Tomohisa Kamikawa, Takashi Kunimoto, Yuji ...2003 Volume 72 Issue 10 Pages 2464-2467
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSHigh field ESR measurements of Cu3(CO3)2(OH)2 have been performed in the frequency region from 50 to 900 GHz and in the temperature region from 1.8 to 265 K using the pulsed magnetic field up to 36 T. The large g-shifts below 23 K and the characteristic temperature dependence of the linewidth are discussed in connection with the two maxima of magnetic susceptibility observed at 5 and 23 K. Our ESR results together with the magnetization and theoretical results suggest that the ground state of the system is in the spin fluid (SF) phase at low field and low temperature. From the frequency–field dependence measurements at 1.8 K, the direct transition, which is closely related to the magnetization plateau from 16 to 26 T at 1.5 K, is observed for the first time. The observed frequency–field diagram suggests that the exchange interaction in the dimer is estimated to be about 50 K (1057 GHz).View full abstractDownload PDF (663K) -
Makiko Nonomura, Ryo Kobayashi, Yasumasa Nishiura, Masatsugu Shimomura2003 Volume 72 Issue 10 Pages 2468-2471
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe present a model of motion and evaporation of a droplet of a solute along with precipitation. It is demonstrated that the model can simulate the formation of stripe patterns parallel to the droplet edge resulting from periodic precipitation.View full abstractDownload PDF (143K) -
Hyeon-Deuk Kim, Hisao Hayakawa2003 Volume 72 Issue 10 Pages 2473-2476
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe examine information theory using the steady-state Boltzmann equation. In a nonequilibrium steady-state system under steady heat conduction, the thermodynamic quantities from information theory are calculated and compared with those from the steady-state Boltzmann equation. We have found that information theory is inconsistent with the steady-state Boltzmann equation.View full abstractDownload PDF (82K) -
Riki Kawashima, Jun-ichi Fukui, Katsunori Haruki, Hiroshi Isoda2003 Volume 72 Issue 10 Pages 2477-2480
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSTime series of ac conductivities at 2 kHz have been measured at 223.15 K for c-axis of the rare earth nitrate crystals R(NO3)36H2O, having the metastable phenomena, where R is rare earth element (R = 57La, 58Ce, 59Pr, 60Nd, 62Sm, 63Eu, 64Gd, 65Tb, 66Dy, 67Ho, 68Er, 69Tm, 70Yb and 71Lu). The variation in the time series of the conductivities was found by changing the rare earth element in the crystal. The power spectral density P(f) derived from the time series data, shows dependence on frequency f, represented by power law P(f)∝f−α and peak near the frequency fMax. The numerical values of the exponent α and fMax are dependent on the rare earth element sequence. The form of the function for fMax to the sequence of R is similar to the magnetic characteristics.View full abstractDownload PDF (3798K) -
Hiroshi Ezawa, Toru Nakamura, Keiji Watanabe, Frederik W. Wiegel2003 Volume 72 Issue 10 Pages 2481-2496
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSFor a 2-dimensional Brownian motion ω(t) starting from x0 at t=0 and for a given function V(x), x∈\\mathbbR2, we determine (i) a normalization factor ν(T) such that the random variable, X[ω]=limT→∞ν(T)−1∫0TV(ω(t))dt, converges in law to have a nontrivial statistical distribution and (ii) the distribution itself. Assuming that ∫\\mathbbR2V(x)d2x≠0, we use a perturbation theory approach and obtain the complete sum of the series to find out that ν(T) is logT and the probability distribution is one-sided exponential, independent of the starting point of the Brownian motion and the shape of V(x) under the condition that V(x)∈L1(\\mathbbR2)∩Lp(\\mathbbR2) for some p>1 and its Fourier transform be Lipschitz continuous (order arbitrary) at the origin. This condition is slightly different from that of Kallianpur and Robbins who obtained the same result using a different method. We give an estimate, important in practical application of our results, of how long T should be in order that the difference between the probability distributions for finite time T and its limit can be ignored. One dimensional case is treated in Appendix B.View full abstractDownload PDF (261K) -
Kazuo Sasaki2003 Volume 72 Issue 10 Pages 2497-2508
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSBased on the Fokker–Planck equation, a formula for the effective diffusion coefficient D is derived for a Brownian particle undergoing one-dimensional motion in a two-state Brownian motor (ratchet) in which a spatially periodic, asymmetric potential acting on the particle switches between two states stochastically. It turns out that D is in close relation to the “mobility” μ defined as dv⁄dF where v is the average velocity of the particle and F is the external force acting on it. The formula is applied to specific examples, and it is found that inequality D≥μkBT, with kB the Boltzmann constant and T the temperature, holds in all the cases investigated. In the light of new results obtained here, an earlier analysis of a biological molecular motor KIF1A based on the “on–off” ratchet is re-examined.View full abstractDownload PDF (371K) -
Giovanni Fazio, Giorgio Giardina, Antonino Lamberto, Roberto Ruggeri, ...2003 Volume 72 Issue 10 Pages 2509-2522
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe study the effect of the entrance channel and the shell structure of reacting massive nuclei on the fusion mechanism and the formation of evaporation residues of heavy and superheavy nuclei. In the framework of the combined dinuclear system concept and advanced statistical model, we analyze the 40Ar + 176Hf, 86Kr + 130Xe and 124Sn + 92Zr reactions leading to 216Th*; the 32S + 182W, 48Ti + 166Er, and 60Ni + 154Sm reactions leading to 214Th*; the 40Ar + 181Ta reaction leading to 221Pa*; the 48Ca + 248Cm reaction leading to the 296116 compound nucleus. In our calculations of the excitation functions for capture, fusion and evaporation residues we use the relevant variables such as mass-asymmetry of nuclei in the entrance channel, relative distance between nuclear centers, shell effect and shape of colliding nuclei and such characteristics of the reaction mechanism as potential energy surface, driving potential, the dependence of capture, fusion cross sections and survival probability of compound nucleus on the orbital angular momentum. As a result we obtain a beam energy range for the capture of the nuclei before the system fuses and the Γn⁄Γf ratio at each step along the de-excitation cascade of the compound nucleus. Calculations allow us to reach useful conclusions about the mechanism of the fusion–fission process, that is in competition with the quasifission process, and the production of the evaporation residues.View full abstractDownload PDF (350K) -
A. H. Khater, W. Malfiet, M. H. M. Moussa, S. F. Abdul-Aziz2003 Volume 72 Issue 10 Pages 2523-2529
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSUsing the symmetry method, we analyze the Calogero–Degasperis–Fokas modified KdV equation ut+uxxx−aux3−f(u)ux=0; a∈\\mathbbR, where the function f solves f'''(u)=8af′(u). The infinitesimals, similarity variables, dependent variables, and reduction to quadrature or exact solutions of this equation for physically realisable forms of f(u) are also obtained. Some interesting outcomes of this study are the deductions of the new exact solutions, that does not seem to have been reported in the literature.View full abstractDownload PDF (109K) -
Jun-Hoi Lee, Kee-Ju Jeong2003 Volume 72 Issue 10 Pages 2530-2532
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe argon temperature and the emission intensity in the hollow cathode discharge were measured. We measured the line profiles of the 1s5–2p8 transition in argon, using a single-frequency diode laser. Low power diode lasers have been used to investigate the line profiles of argon transitions in hollow cathode discharges. It turns out that the argon temperature is 640–783 K in the discharge current range of 7.00–10.0 mA. The emission intensity is uniform in the negative glow at the current range over 5.00 mA under the pressure of 3.00 Torr.View full abstractDownload PDF (103K) -
Mitsuo Machida, Hideaki Itho, Nobumitsu Koyano2003 Volume 72 Issue 10 Pages 2533-2538
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe mode-coupling between the rotational and translational motions in the monoclinic K2ZnBr4 was studied by the molecular dynamics simulation and X-ray structure analysis. In the structure analysis, the Fourier analysis indicates that, in the paraelectric phase, electron densities of the bromines Br1 and Br2 on the mirror plane are fairly elongated in the b direction, while the density of the bromine Br3 at the general position spreads more or less in the a direction. In the ferroelectric phase, the elongation is suppressed in particular for Br1 and Br2, and the densities of Br3 and Br4, which are equivalent each other in the paraelectric phase, are nearly isotropic. In addition, Br1 and Br2 displace in the b direction through the rotation of the ZnBr42− ion about the a axis. In the simulation, the ZnBr42− ions are treated as rigid-bodies. The trajectories of the bromines reproduce satisfactorily the characteristic feature of the Fourier maps. This means that the ZnBr42− ions are approximately regarded as rigid-bodies even in the real K2ZnBr4. The mode-coupling analysis shows that, in the ZnBr42− rigid-bodies, the rotational motion about the a axis and the translational motion in the b direction couple strongly. Moreover, the displacements of rotational and translational motions in the b direction are almost synchronous for Br1 and Br2, and almost asynchronous for Br3 and Br4.View full abstractDownload PDF (452K) -
Hiroaki Ishida, Satoshi Motoyama, Kazuki Mae, Yasuaki Hiwatari2003 Volume 72 Issue 10 Pages 2539-2545
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe martensitic transformations in NiAl alloys were studied using molecular dynamics simulations. The modified embedded atom method was used with the pseudo monoatomic potentials which included angular dependence of each atoms. The thermally induced B2 → 3R martensitic and 3R → B2 reverse martensitic transformations have been obtained in the present molecular dynamics simulations for the first time with a bulk (no surface) computational model. The transformation is accompanied by a twin in the 3R phase which leads to a lattice-invariant deformation and minimize the transformation strain energy. The concentration dependence of the transformation temperature for NixAl1−x (0.58<x<0.69) alloys have been observed.View full abstractDownload PDF (336K) -
Kanwar Jit Singh, Ryu Satoh, Yoshimi Tsuchiya2003 Volume 72 Issue 10 Pages 2546-2550
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSMolar volume and sound velocity measurements were carried out in the liquid Sb–Te system as a function of temperature and composition. Results obtained have been used to deduce the compressibility and thermal expansion coefficient. Molar volume and adiabatic compressibility show a distinct cusp at the Sb2Te3 composition, which suggests the persistence of stable association in the liquid. At low temperatures near the liquidus line, mentioned thermodynamic parameters show behaviour characteristic of structural changes with temperature. Large specific heat anomaly reported previously can be ruled out from the present experiments.View full abstractDownload PDF (278K) -
Kazutaka Kudo, Takashi Noji, Yoji Koike, Terukazu Nishizaki, Norio Kob ...2003 Volume 72 Issue 10 Pages 2551-2555
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have succeeded in growing large-size single-crystals of the four-leg spin–ladder system La2Cu2O5 by the traveling-solvent floating-zone method, and also investigated the thermal conductivity. The thermal conductivity along the leg of the ladder, κb, has been found to be much larger than that perpendicular to the ladder plane, κa. The temperature dependence of κb exhibits a peak at 22 K and a shoulder at 12 K. The peak is a little enhanced by the application of a magnetic field of 14 T. The large value of κb is explained as being due to the large contribution of magnons to the thermal conductivity.View full abstractDownload PDF (319K) -
Masako Saito, Takahiko Sasaki, Hidetoshi Fukuyama2003 Volume 72 Issue 10 Pages 2556-2567
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSBased on the exactly solvable model, various features of orbital magnetism of mesoscopic ring systems with finite width have been studied in various regimes of temperature and magnetic field with special emphasis on the spatial distribution of persistent current and resultant magnetization. When the width is very narrow and only one channel along the ring is occupied, Aharonov–Bohm (AB) oscillation appears due to interference effects at low temperature; its amplitude is, however, seen to be suppressed as the magnetic field increases because of the finite width. When the width is not very narrow and several channels are occupied, AB oscillation is transformed into mesoscopic fluctuations as seen in disc systems. De Haas–van Alphen (dHvA) oscillation also appears in this regime. At high temperature where all of AB oscillation, mesoscopic fluctuations and dHvA oscillation fade away, Landau diamagnetism whose magnitude is proportional to the effective area of the ring appears irrespective of the width of the ring. A wide ring with only a small hole in its center has been also studied and compared with the case of a disc. Phase diagrams in the plane of temperature and magnetic fields are systematically presented both for narrow and wide rings.View full abstractDownload PDF (1559K) -
Yisong Zheng, Tsuneya Ando2003 Volume 72 Issue 10 Pages 2568-2577
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA correlation function is derived for interface roughness in lateral superlattices realized in corrugated quantum wells. It is given by a sinusoidal function with an exponential decay in the direction of the superlattice. Its validity is examined by a model in one dimension. The anisotropic conductivity is calculated by solving the Boltzmann transport equation exactly in the absence of a magnetic field and in a self-consistent Born approximation in high magnetic fields.View full abstractDownload PDF (304K) -
Mikito Koga2003 Volume 72 Issue 10 Pages 2578-2588
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA nonunitary superconducting state coexisting with an itinerant ferromagnetic order is studied. The triplet Cooper pair’s moment couples with the magnetic moment. Even in the presence of strong anisotropy both for the superconducting order parameter and for the exchange coupling, the transverse moment can be induced, resulting in a different orientation of the magnetic moment. The necessary conditions are discussed on the basis of a BCS model for the unconventional superconductivity.View full abstractDownload PDF (168K) -
Akira Masago, Naoshi Suzuki2003 Volume 72 Issue 10 Pages 2589-2598
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSFor the eg Hubbard model on a simple cubic lattice group theoretical classification of mean field solutions have been made by assuming four kinds of single-Q wave vectors (0,0,0), (0,0,π), (π,π,0) and (π,π,π), and collinear magnetic states. Twenty-one broken symmetry states have been obtained in detail. Besides the usual charge and spin ordering states the so-called orbital orders of the two eg states, φ1=(3z2−r2)⁄\\sqrt3 and φ2=x2−y2, or their linear combinations have been derived. It is shown that the broken symmetry states corresponding to ordering of the complex orbital states Ψ1=\\frac1\\sqrt2(φ1−iφ2) and Ψ2=\\frac1\\sqrt2(φ1+iφ2) represent octupole ordering. Finally quite exotic broken symmetry states consisting of combination of charge, spin and orbital orderings are derived.View full abstractDownload PDF (185K) -
Melike Abliz, Koichi Kindo, Kazuo Kadowaki, Hiroyuki Takeya2003 Volume 72 Issue 10 Pages 2599-2603
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSHigh-field magnetization measurements of single-crystal HoNi2B2C has been performed in magnetic fields up to 55 T. A broad and large transition is observed around 25 T for the magnetic hard ⟨001⟩-axis below 40 K. Below the Neel temperature 5 K, a two-step-like magnetization has been seen in the low field region for the easy axis. We have calculated the magnetization taking into account the crystalline electric field (CEF). The CEF parameters and eigen states of Ho3+ are determined by a simulation of the temperature-dependence of magnetic susceptibility in HoNi2B2C. The calculated magnetization, using obtained CEF parameters, shows good agreement with experimental data. The broad transition for the ⟨001⟩-axis could be explained by the energy level crossing of the 4f electron in the CEF model.View full abstractDownload PDF (231K) -
Hirofumi Wada, Akihiro Mitsuda, Tomoko Yoshida, Takashi Yamamoto, Tsun ...2003 Volume 72 Issue 10 Pages 2604-2607
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe examined the temperature dependence of the Eu valence in La0.9Eu0.1Ni2(Si1−xGex)2 by means of magnetic susceptibility measurements and X-ray absorption spectroscopy. It was found that the Eu ions are in the intermediate valence state for 0.2≤x≤0.8 and the Eu valence gradually varies with temperature. The results are compared with those of the concentrated EuNi2(Si1−yGey)2 compounds. The main factor in determining the Eu valence in both dilute and concentrated alloys is discussed.View full abstractDownload PDF (163K) -
Yoichi Nishiwaki, Katsunori Iio, Toshiharu Mitsui2003 Volume 72 Issue 10 Pages 2608-2613
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSuccessive structural phase transitions with ferroelectricity were found in TlCoCl3 through dielectric constant measurements and D–E hysteresis loop observations. The sequence of the transitions is identical with that in RbMnBr3 and TlFeCl3, which undergo successive transitions from the prototype crystal structure of CsNiCl3. The temperature dependence of the magnetic susceptibility below TN1 indicates the presence of successive magnetic orderings, which has not been observed in the Ising-like antiferromagnets CsCoCl3 and CsCoBr3 without structural transitions. Dielectric dispersion attributable to the Ising-spin dynamics on a linear-chain spin system was observed at low temperatures. Several problems to be solved are proposed for understanding structural and magnetic properties of TlCoCl3.View full abstractDownload PDF (281K) -
Takashi Ikeda, Yorihiko Tsunoda2003 Volume 72 Issue 10 Pages 2614-2621
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA new spin frustration system with an octahedral configuration of magnetic atoms was found. In neutron scattering measurements for an ordered Mn3Pt alloy, inelastic diffuse scattering intensity distributes along the first Brillouin zone-boundary of the fcc structure in the paramagnetic and the F-phases. Within the calculations based on a RPA, the experimental data in the paramagnetic phase are reproduced using antiferromagnetic couplings between the spins up to the third-neighbor exchange interactions. In the F-phase below the Néel temperature, a part of the Mn spins still fluctuates at the special site. The existence of the F-phase is a characteristic of the octahedral spin frustration system. The effects of the chemical disorder on the spin frustration are also studied using a specimen with a small atomic LRO parameter.View full abstractDownload PDF (325K) -
Shugo Ikeda, Naoto Metoki, Yoshinori Haga, Koji Kaneko, Tatsuma D. Mat ...2003 Volume 72 Issue 10 Pages 2622-2626
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA single crystal of uranium ternary intermetallic compound UPdGa5 was grown by the Ga self-flux method. The magnetic susceptibility showed a weak temperature dependence and small anisotropy, consistent with an itinerant character of 5f electrons. We observed a clear drop in the susceptibility and electrical resistivity below the Néel temperature TN=31 K. The magnetic structure was studied by means of a neutron diffraction measurement. We observed an antiferromagnetic peak with the propagation vector Q=[0,0,1⁄2]. The uranium 5f moment of 0.33(4)μB/U parallel to the c-axis was found to order ferromagnetically in the basal c-plane and coupled antiferromagnetically along the c-axis.View full abstractDownload PDF (648K) -
Kazuo Hida2003 Volume 72 Issue 10 Pages 2627-2631
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe mixture of bond-alternating and uniform S=1⁄2 antiferromagnetic Heisenberg chains is investigated by the density matrix renormalization group method. The ground state magnetization curve is calculated and the exchange parameters are determined by fitting to the experimentally measured magnetization curve of CuCl2xBr2(1−x)(γ-pic)2. The low field behavior of the magnetization curve and low temperature behavior of the magnetic susceptibility are found to be sensitive to whether the bond-alternation pattern (parity) is fixed all over the sample or randomly distributed. The both quantities are compatible with the numerical results for the random parity model.View full abstractDownload PDF (240K) -
Arumugam Thamizhavel, Andrei Galatanu, Etsuji Yamamoto, Tomoyuki Okubo ...2003 Volume 72 Issue 10 Pages 2632-2639
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA series of the ternary compounds CeTBi2 (T: Ni, Cu and Ag) have been grown in the single crystalline form by means of the flux method. These compounds crystallize in the tetragonal crystal structure. Measurements of the electrical resistivity, magnetic susceptibility, magnetization, low temperature specific heat and de Haas–van Alphen effect are reported. These compounds order antiferromagnetically with an easy-axis of magnetization along the [001] direction(c-axis). The electrical resistivity and magnetic susceptibility are highly anisotropic, reflecting the quasi-two dimensional crystal structure.View full abstractDownload PDF (2181K) -
Takateru Kawakami, Saburo Nasu, Toshio Tsutsui, Tetsuya Sasaki, Takahi ...2003 Volume 72 Issue 10 Pages 2640-2645
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSUsing a diamond anvil cell, 57Fe Mössbauer spectroscopy has been carried out on maghemite, γ-Fe2O3, under high pressure up to 30 GPa. Maghemite transforms to hematite, α-Fe2O3, with a wide coexistent pressure range. The onset of phase transformation is 14 GPa and complete transformation to hematite is found at 26 GPa. The pressure-induced transformation is irreversible and hematite is preserved at decompression process. At decompression from 30 GPa the quadrupole splitting of hematite varies as a function of pressure, changing its sign at 11 GPa and room temperature, since Morin transition temperature is below room temperature at 11 GPa and the 90° spin rotation occurs. And furthermore, we clarified the orientation of a magnetization to exploit a characteristic in Mössbauer spectroscopy. The angle between the incident γ-ray and the magnetization direction changes from random to nearly parallel with the increase of pressure. The magnetization direction maintains nearly parallel after maghemite transforms to hematite. This strong orientation of magnetization does not appear in compressed original hematite. This orientation is characterized by the transformation.View full abstractDownload PDF (221K) -
Atsushi Tanji, Xie Hai Yan, Ichiro Akai, Tsutomu Karasawa, Vadim F. Ag ...2003 Volume 72 Issue 10 Pages 2646-2655
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDynamical processes of high-density excitons and their relaxation mechanisms in GaSe crystals have been investigated in real and momentum spaces by observing resonant luminescence spectra of the excitons in the time- and space-resolved regimes. Temporal profiles of the luminescence show remarkable excitation-density dependence. The temporal profiles have been well explained by a nonlinear rate equation including a two-exciton scattering process and localization to shallow trapping states at high density. Above a certain excitation density, spatial propagation becomes remarkable owing to the suppression of localization due to site-filling effects, giving the group velocity ∼1.0×108 cm/s. The other characteristic features of the exciton dynamics at high density appear as inelastic scattering processes on recoil luminescence bands in the time- and space-resolved spectra. From these results, detailed scattering and relaxation mechanisms of the excitons in this material at high density have been clarified in the momentum space.View full abstractDownload PDF (326K) -
Tomoaki Yoshioka, Hidekatsu Suzuura, Tsuneya Ando2003 Volume 72 Issue 10 Pages 2656-2664
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSElectronic states are calculated in boron carbonitride (BCN) alloy nanotubes with a simple tight-binding model. Random replacement of carbon atoms with boron and nitrogen (B–N) ones in metallic carbon nanotubes mainly causes level broadening and the nanotubes remain metallic. On the other hand, the energy gap of boron nitride (BN) nanotubes always survives under random substitution of B–N atoms by carbon ones while it becomes smaller than the original gap. Further, the optical gap does not correspond well with the band gap of the density of states in nanotubes with high B–N concentration. This can be understood in terms of localized states associated with carbon impurities in a BN nanotube.View full abstractDownload PDF (365K) -
Yuichi Takasu, Yuji Miyashita, Yukiko Kasai, Izumi Nishio2003 Volume 72 Issue 10 Pages 2665-2670
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe dynamic network structures of water molecules surrounding acetone molecule and DMSO molecule are investigated by low frequency Raman spectroscopy. Acetone molecule and DMSO molecule have very similar molecular structures with only one difference in the central atom; it is a carbon for acetone and is a sulfur for DMSO. These differences manifest themselves as the differences of dipole moment of each molecule which result in a very different behavior of their aqueous solutions. Observed Raman spectra are analyzed by the linear combination of Raman spectrum of pure water and that of pure solute. We found that besides the linear combination of two spectra the extra damped harmonic oscillation mode was required for the cancellation of the systematic deviation from observed spectra. It is also found that the extra oscillation mode shows strong solute dependence. Using this solute dependence of the extra oscillation mode, we found that acetone molecules promote the ordered structure of water molecules while DMSO molecules prevent the formation of the ordered structure of water molecules.View full abstractDownload PDF (534K) -
Yasutami Takada, Tian Cui2003 Volume 72 Issue 10 Pages 2671-2677
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSAccuracy of the Born–Oppenheimer adiabatic approximation to the ground state of a hydrogenlike molecule (M+M+m-m−) is examined in comparison with the exact results obtained by diffusion Monte Carlo simulations, fully incorporating quantum fluctuations. For the mass ratio m⁄M<0.1, the relative error in the ground-state energy is found to be less than 1%. We discuss the change in nature of the binding mechanism of this system with the increase of m⁄M from the usual chemical bonding at m⁄M<<1 to the one in which nonadiabatic effects such as the retardation of electron response to proton motion play a crucial role.View full abstractDownload PDF (149K) -
Tetsuya Matsuzaki, Masahiro Nakagawa2003 Volume 72 Issue 10 Pages 2678-2684
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThis paper presents a chaos neuron model represented by the fractional differential equation as a novel artificial neuron model. This model has an ability of a chaotic response which depends on the differential order and delay term in the dynamics. There is also observed a burst response in a certain parameter of chaotic region. We investigate basic characteristics of the model by some observations such as time-sequential data, bifurcation diagram for the differential order, and Lyapunov exponent analysis to the fractional differential system including delay. The result of the Lyapunov analysis confirms the existence of chaos on the presently proposed neuron model.View full abstractDownload PDF (199K) -
Jun Shibata, Y-h. Taguchi2003 Volume 72 Issue 10 Pages 2685-2689
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have investigated the relationship between height and spacing of Barchan dunes which the coupled map lattice model numerically generates. There is a scaling relation between them and the values of the scaling exponents agree well with real dunes’ values. The values of these scaling exponents are the same for both steady states and transient states.View full abstractDownload PDF (195K) -
Masaki Hida, Katsuya Honda2003 Volume 72 Issue 10 Pages 2690-2691
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (1167K) -
Yasuaki Okada, Yoshihiko Inada, Andrei Galatanu, Etsuji Yamamoto, Riki ...2003 Volume 72 Issue 10 Pages 2692-2693
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (345K) -
Hirotaka Manaka, Isao Yamada, Yoshiharu Miyajima, Masayuki Hagiwara2003 Volume 72 Issue 10 Pages 2694-2695
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (123K) -
Takayuki Makino, Yusaburo Segawa, Masashi Kawasaki, Yuji Matsumoto, Hi ...2003 Volume 72 Issue 10 Pages 2696-2697
Published: October 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (134K)