Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 73, Issue 2
Displaying 1-36 of 36 articles from this issue
  • Chun-Long Zheng, Li-Qun Chen
    2004 Volume 73 Issue 2 Pages 293-295
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Using the Painlevé–Bäcklund transformation and a multilinear variable separationapproach, an exact variable separation excitation of the generalthree-dimensional Korteweg de Vries system is derived first. Based on the derived excitation, a new type of solitary wave, i.e., a semifolded localized coherent structure, is constructed.
    Download PDF (106K)
  • Hideaki Kitahara, Takeshi Kawaguchi, Junichi Miyashita, Ryoko Shimada, ...
    2004 Volume 73 Issue 2 Pages 296-299
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    One-dimensional dual-periodic photonic crystals were fabricated using periodic microstrip lines. Singular Bloch modes with an extremely high Q factor of 170 in the crystals were successfully obtained in the bandgap region. The measured transmission and reflection spectra were in very good accordance with those calculated by the method of moments. The spatial distribution of the electrical current in the singular Bloch modes of the electromagnetic wave was simulated using the method of moments, and the localization of the singular Bloch modes was clearly evident. The spatial distribution pattern of the electrical current in the modes was not localized in the restricted area of the line. This was not similar to that in impurity modes for a simple periodic photonic crystal, that is, the pattern expanded over the entire line.
    Download PDF (262K)
  • Jun-ichiro Suda, Mitsugu Matsushita
    2004 Volume 73 Issue 2 Pages 300-302
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Specific morphologies occasionally appear in the crystal growth in gels. Potassium dichromate (K2Cr2O7) crystals grown in gelatin gel have been found to exhibit various morphologies by varying only initial concentrations of K2Cr2O7 and gelatin in the medium. Particularly unique are huge helical crystals grown under the condition of high concentrations of both solute and gelatin, and right-handedness is overwhelmingly superior to left-handedness in helical chirality. We have found for the first time that huge left-handed helical crystals grow when adding acidic amino acids such as aspartic acid or glutamic acid, revealing the existence of an enantiomer of huge helical crystals of K2Cr2O7. The present finding is expected to be relevant to biocrystallization such as the growth of seashells.
    Download PDF (152K)
  • Hiroya Ishikawa, Takashi Itoh, Masato Hashimoto, Susumu Fujiwara
    2004 Volume 73 Issue 2 Pages 303-306
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Temperature dependence of crystal structures is examined with X-ray diffraction at normal pressure or elevated pressures for solution-grown nylons with octamethylene moiety between amino or carboxy groups (nylons 82, 410, 610, 810). Although octamethylene moiety between amino groups has the potential to cause the phase transition, the low melting point veils the transition appearance. Considering this comprehensively with previous results, it is concluded for all even–even nylons, that the phase transition in the two-dimensional methylene layer system can be experimentally observed only in nylon 6Y (Y≤8) crystals at normal and/or high pressures, where the hexamethylene moiety between amino groups plays an intrinsic role. The so-called ‘Brill transition’ widely reported for melt-crystallized nylons is not a phase transition but an abrupt thermal expansion.
    Download PDF (114K)
  • Mikio Eto, Takashi Ashiwa, Mikio Murata
    2004 Volume 73 Issue 2 Pages 307-310
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    We propose an entanglement mechanism of nuclear spins in quantum dots driven by the electric current accompanied by the spin flip. This situation is relevant to a leakage current in spin-blocked regions where electrons cannot be transported unless their spins are flipped. The current gradually increases the components of larger total spin of nuclei. This correlation among the nuclear spins markedly enhances the spin-flip rate of electrons and hence the leakage current. The enhancement of the current is observable when the residence time of electrons in the quantum dots is shorter than the dephasing time T2* of nuclear spins.
    Download PDF (116K)
  • Masato Kishi, Yasuhiro Hatsugai
    2004 Volume 73 Issue 2 Pages 311-314
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Dielectric responses of a one-dimentional electron system are investigated numerically. We treat an interacting one-dimentional spinless fermion model with disorder by using the density matrix renormalization group (DMRG) method which is extended for nonuniform systems. We apply an electric field E to the system and calculate dielectric responses. The dielectric responses of the Mott insulator and the Anderson insulator are calculated. Steplike behaviors in the PE curve are obtained which correspond to the breakdown of the insulating behavior. For the Mott insulator, the steps originate from the generation of kink pairs. For the Anderson insulator on the other hand, the origin of the steps is the crossing of localized one-particle energy levels. We also treat random systems with interaction. By one-parameter scaling analysis of the susceptibility χ, the metal–insulator transition in an attractively interacting region is confirmed and a phase diagram of the random spinless fermion model is obtained.
    Download PDF (126K)
  • Masahito Yoshizawa, Yoshiki Nakanishi, Tomoyuki Kumagai, Masafumi Oika ...
    2004 Volume 73 Issue 2 Pages 315-318
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The longitudinal and transverse elastic constants of polycrystalline SmRu4P12 have been measured as a function of temperature in the magnetic field up to 12 T. The transverse elastic constant shows a weak softening toward low temperatures. Both longitudinal and transverse elastic constants show a large anomaly below the metal–insulator transition TMI=16 K. These elastic anomalies indicate the ground state of the crystalline electric field multiplet to be Γ8, and that the quadrupole ordering is responsible for this metal insulator transition. The successive anomalies of SmRu4P12 have been clearly observed by ultrasonic measurements. An elastic anomaly was found at T*, which is 14 K in the absence of a magnetic field. TMI increases and T* decreases under the application of the magnetic field. The anomaly at T* is markedly enhanced by the application of a magnetic field.
    Download PDF (100K)
  • Yasuhiro Tanaka, Youichi Yanase, Masao Ogata
    2004 Volume 73 Issue 2 Pages 319-322
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    A new mechanism of superconductivity due to charge fluctuation in the newly discovered Co-based oxide is proposed. A single-band extended Hubbard model on a triangular lattice is studied within the random phase approximation. f-wave triplet superconductivity is stabilized in the vicinity of charge–density–wave instability, which is in sharp contrast to the square-lattice case. The physical origin of the realization of the f-wave triplet state as well as its relevance to experiments are discussed.
    Download PDF (212K)
  • Mikio Shimizu
    2004 Volume 73 Issue 2 Pages 323-326
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Using spectrophotometry, it was found that histidine enhances weakly but specifically various metabolic reaction rates such as pyruvate carboxylase, oxalacetate decarboxylase and glucose-6-phosphate isomerase (indicating that only one of the twenty amino acids is catalytic). Oligo-ribonucleotides having flexible dihedral angles could also be expected to be rate enhancers in these metabolic reactions. The survey by spectrophotometry showed that GpUpG, an anticodon of histidine, is also a similar rate enhancer. The formation of the reaction products in the cases of pyruvate carboxylase and oxalacetate decarboxylase was furthermore confirmed by thin-layer chromatography using 14C-labeled pyruvate and by high-performance liquid chromatography. The origin of the genetic code may thus be based on direct molecular relationships between amino acids and anticodons.
    Download PDF (102K)
  • Chun-Xia Li
    2004 Volume 73 Issue 2 Pages 327-331
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    By introducing a 4×4 matrix spectral problem with three potentials, A hierarchy of nonlinear evolution equations are derived. An interesting equation in the hierarchy is a coupled KdV equation. It is shown that the hierarchy possesses the generalized bi-Hamiltonian structures with the aid of the trace identity. Through the nonlinearization of eigenvalue problems, a new infinite-dimensional Hamiltonian system is presented, which is completely integrable in Liouville sense.
    Download PDF (87K)
  • Norio Inui
    2004 Volume 73 Issue 2 Pages 332-339
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Irradiation generates free carriers inside silicon and it can cause enhancement of the Casimir force between silicon membranes. We study numerically the temporal behavior of the Casimir force between two parallel silicon membranes after irradiating the surface with UV pulse laser. In the calculation, the free carrier density is obtained by solving the diffusion equation with the generation and recombination terms, and the dielectric function of the illuminated silicon is calculated from them by employing the Drude model. Based on the Lifshitz theory accounting for thickness of the slabs, we calculate the Casimir force as a function of time and consider the finite size effect of the thickness.
    Download PDF (194K)
  • Tomo Munehisa, Yasuko Munehisa
    2004 Volume 73 Issue 2 Pages 340-347
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    We apply a recently developed stochastic method to the Shastry–Sutherland model on 4×4 and 8×8 lattices. This method, which we call the Stochastic State Selection Method here, enables us to evaluate expectation values of powers of the Hamiltonian with very limited number of states. In this paper we first apply it to the 4×4 Shastry–Sutherland system, where one can easily obtain the exact ground state, in order to demonstrate that the method works well for this frustrated system. We numerically show that errors of the evaluations depend much on representations of the states and that the restructured representation is better than the normal one for this model. Then we study the 8×8 system to estimate energy eigenvalues of the lowest S=1 state as well as of the lowest excited S=0 state, where S denotes the total spin of the system. The results, which are in good accordance with our previous data obtained by the Operator Variational method, support that an intermediate spin-gap phase exists between the singlet dimer phase and the magnetically ordered phase. Estimates of the critical coupling and of the spin gap for the transition from the dimer phase to the intermediate phase are also presented.
    Download PDF (142K)
  • Yousuke Nishikawa, Eiji Kimura, Takeshi Kai, Yukikazu Itikawa, Shinobu ...
    2004 Volume 73 Issue 2 Pages 348-352
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Differential cross sections for elastic scattering of electrons from Al2+ and Ar7+ are calculated with the R-matrix method. Using six different sets of coupled states, the convergence is tested against the number of coupled states in the calculation. The converged cross section is analysed in terms of the contributions of the long-range Coulomb force, the short-range electrostatic interaction and the interference of those two. A comparison with the recent measurement at 100 eV for Ar7+ shows disagreement in the vicinity of a scattering angle of 50°.
    Download PDF (160K)
  • Xiao Chen, Bo-qiang Xu, Rong-qing Xu, Zhong-hua Shen, Jian Lu, Xiao-wu ...
    2004 Volume 73 Issue 2 Pages 353-357
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Measurement of laser-generated transient Lamb waves propagation has been performed in 0.25 mm-thick iron plate by using a fibre sensor based on optical beam deflection technique. The detection principle of this optical method is discussed in detail. A high-powered Q-switched Nd:YAG laser was used to excite Lamb waves on the polished surface of iron plate. The well-defined Lamb waveforms, as well as their properties of oscillation and dispersion are presented in this paper. Furthermore, according to the ablation model, the development and propagation of Lamb waves are numerical simulated by the finite element method that has been widely used in laser ultrasonic field. The experimental results show good agreement with the numerical simulation. Therefore, this optical detection technique has considerable potential in ultrasonic field.
    Download PDF (114K)
  • Tsunehiro Yokoi, Hiroyasu Yamada, Kazuhiro Nozaki
    2004 Volume 73 Issue 2 Pages 358-363
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    We present various exact solutions of a discrete complex Ginzburg–Landau (CGL) equation on a plane lattice, which describe target patterns and spiral patterns and derive their stability criteria. We also obtain similar solutions to a system of van der Pol’s oscillators.
    Download PDF (225K)
  • Nobuyuki Aiba, Shinji Tokuda, Takaya Hayashi, Masahiro Wakatani
    2004 Volume 73 Issue 2 Pages 364-373
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    In tokamaks, it is observed that an ablated and ionized pellet moves toward the low field side of the torus. This phenomenon can be considered as the magnetohydrodynamic (MHD) wave propagation in the 1⁄R varying toroidal field because the pressure perturbation is induced by injecting a pellet, where R is the major radius of tokamaks. The dominant mechanism which causes this displacement is revealed, by solving nonlinear MHD equations numerically, as the multi-dimensional nonlinear fast magnetosonic wave propagation in a toroidal magnetic field. Linear wave propagation does not work for this displacement. The nonlinearity is clarified by successive approximation.
    Download PDF (512K)
  • Ezat Keshavarzi, Hossein Nikoofard, Abbas A. Rostami
    2004 Volume 73 Issue 2 Pages 374-379
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    In the recent article, we have calculated the long-range correlation length, ξ, for monatomic fluids near the critical region using our theoretical model for the direct correlation function, DCF. In this model the core of DCF has assumed modified Percus–Yevice function for the DCF of hard sphere and its tail has been considered as a Mayer-f function type via an effective pair potential. In this article, we have predicted the behaviour of low-angle structure of factor, S(k). Since, the model is able to predict the divergence behaviour of S(0) at this region which is related to critical fluctuation phenomena, we may obtain ξ via that. Also, since the DCF is always short-range at any thermodynamic state, we may obtain the coefficients of small-k expansion of c(k), Fourier transform of DCF, which are related to the intermolecular interactions at the critical region. In all cases, the coefficient of k2 term in the expansion of c(k), c2, which is related to correlation length, is negative because S(k) shows Ornestine–Zernike behaviour at small-k. We have obtained the range of k in which c2 may be calculated from the expansion of c(k). This range depends on the thermodynamic states and decreases far away from the critical point. The correlation length shows divergence behaviour when the critical point approaches. We have shown, for supercritical of Krypton, the variation of correlation length with reduced temperature (TTc)⁄Tc has a power–law relation with a critical exponent equal to 0.89. Finally the relation of the correlation length with effective intermolecular parameters has been investigated.
    Download PDF (122K)
  • Kenji Maruyama, Hideoki Hoshino, Hiroyuki Ikemoto, Hirohisa Endo
    2004 Volume 73 Issue 2 Pages 380-387
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Neutron diffraction measurements for liquid (l-) Te and l-As–Te mixtures (10, 20, 30 and 40 at.% As) have been performed. The first minimum after the first peak of g(r) for l-Te and l-As–Te mixtures is filled up with temperature, and the second peak diminishes substantially and flattens out at high temperature. The temperature variations of g(r) are discussed combining the structural information available from EXAFS and computer simulation results. We propose that the volume contraction near the semiconductor to metal (S–M) transition causes the shrinkage of the inter-chain distance, and the short- and long-distance inter-chain correlations may coexist at high temperature. In the metallic region the –As–Te– chains are inferred to have nearly the same configuration as in l-Te. The prepeak near Q=1.1–1.5 Å−1 is observed for l-As20Te80 and l-As40Te60, which diminishes with increasing temperature. The prepeak in l-As40Te60 lies at lower Q region compared with l-As20Te80. It is concluded that the S–M transition observed for l-Te and l-As–Te mixtures is associated with the transformation to the densely packed configuration composed of shortened chain molecules.
    Download PDF (364K)
  • Junichiro K\\={o}ga, Kengo Nishio, Toshio Yamaguchi, Fumiko Yonezawa
    2004 Volume 73 Issue 2 Pages 388-396
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The structures of low-density and high-density amorphous germanium (a-Ge) are studied, by using the order-N non-orthogonal tight-binding molecular dynamics method, where N is the number of atoms. The initial amorphous configuration is taken from the results of a glass-transition simulation performed in a separate work, with N=512. From this initial configuration, we gradually increase the density of the system. In low-density a-Ge, the short-range order (SRO) is characterized essentially by the four-fold configuration although, at lowest densities, the coordination number is smaller than four, thus indicating that quite a few dangling bonds exist. The tetrahedral nature of the SRO in a-Ge is in substance the same as the SRO of a diamond structure which is the low-pressure form of crystalline germanium (c-Ge). On the other hand, the SRO in high-density a-Ge is similar to that of a β-Sn structure, the latter being the high-pressure form of c-Ge.
    Download PDF (532K)
  • Akihide Takeda, Nobuaki Ikuta
    2004 Volume 73 Issue 2 Pages 397-403
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    A new definition of virtual drift velocity of non-conservative electron swarm in configuration space Wr′ is proposed using flight time integral (FTI) expression in pulsed Townsend (PT). Its appropriateness is shown with the agreement of ionization coefficient defined in PT αPiPWr′ and the Townsend’s first ionization coefficient defined in steady state Townsend (SST) αS. An exact drift velocity measurement of non-conservative electron swarm in configuration space will give Wr′, and the analysis using the drift velocity data will give correct collision cross sections when the definition of Wr′ is used. In addition, the features of the energy distributions and transport coefficients in three observation modes, time of flight (TOF), PT and SST under non-conservative condition are discussed in this paper in relation with the energy conservation in respective modes.
    Download PDF (266K)
  • Yumiko Hirashima, Atsushi Suzuki
    2004 Volume 73 Issue 2 Pages 404-411
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    We report the volume phase transition of poly(N-isopropylacrylamide-co-sodium acrylate) gel. The diameter decrement was observed under the continuous water flow (or exchange) for the cylindrical gels with different diameters at gelation. After the water flow, the diameter of the gel in the limited amount of water was measured as a function of temperature. The volume change of gel was classified into three different behavior, discontinuous, reswelling and continuous. When the gel was flushed by a small and large amount of water, the gel exhibits the well-known discontinuous and continuous phase transition. On the other hand, the gel exhibits a reswelling behavior after the sufficient water flow. The reswelling phase transition is discussed in terms of the exchange of counter ions by the water flow and of the creation and destruction of the intermolecular hydrogen bonding. A simple theoretical model is presented to qualitatively explain the condition for the appearance of the reswelling behavior on the basis of the Landau theory. It was concluded that the phase transition behavior of the present system depends on the initial swelling ratio at a swollen state (and not the gelation diameter), which is controlled by the degree of the water flow (or exchange).
    Download PDF (363K)
  • Norikazu Todoroki, Seiji Miyashita
    2004 Volume 73 Issue 2 Pages 412-416
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    We study the ordered phases and the phase transitions in the stacked triangular antiferromagnetic Ising (STAFI) model with strong interplane coupling modeling CsCoCl3 and CsCoBr3. We find that there exists an intermediate phase which consists of a single phase of so-called partial disordered (PD) type, and confirm the stability of this phase. The low temperature phase of this model is so-called two-sublattice ferri magnetic phase. The phase transition between the PD phase and two-sublattice ferri magnetic phase is of the first order. This sequence of the phases is homomorphic as that in the three-dimensional generalized six-state clock model which have the same symmetry of the STAFI model. By studying distributions of domain walls in one dimensional chains connecting layered triangular lattices, we clarify the nature of the phase transition and give an interpretation of little anomaly of the specific heat.
    Download PDF (200K)
  • Hiroshi Kawai, Osamu Narikiyo
    2004 Volume 73 Issue 2 Pages 417-422
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The vibration of the dimer excited by STM current on Si(001) surface is investigated. We describe this system by the Hamiltonian which has the electron–vibration coupling term as the key ingredient. In order to characterize the transition rates induced by STM current between vibrational states we have introduced the effective temperature of the vibration which differs from the temperature of the substrate. The behavior of the effective temperature depends on the substrate temperature and STM current in highly nonlinear manner and qualitatively changes around 50 K of the substrate temperature. At lower temperatures, the effective temperature strongly deviates from the substrate temperature and reaches a few hundred Kelvin for the typical values of STM current. At higher substrate temperatures, the effective temperature reduces to the substrate temperature. On the basis of these behaviors of the effective temperature, we solve the puzzle of the symmetric–asymmetric crossover in dimer images of STM observation in the ordered state of c(4×2).
    Download PDF (134K)
  • Ajay Gupta, Mukul Gupta, B. A. Dasannacharya, Y. Yoda, S. Kikuta, M. S ...
    2004 Volume 73 Issue 2 Pages 423-429
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Amorphous alloy of Fe–N with ∼40 at.% N has been prepared by reactive ion-beam sputtering. A systematic study of the growth behaviour, thermal stability, atomic diffusion and the magnetic properties of the alloy has been done. Deposition characteristics of the film have been studied using the x-ray reflectivity and the atomic force microscopy techniques. The results suggest that it is a suitable system for preparing isotopic multilayers for application as the nuclear Bragg monochromator. Pure nuclear Bragg reflections have been observed from an isotopic multilayer of composition: float glass (substrate)/[natFeN0.7(30 Å)/57FeN0.7(20 Å)]×10/natFeN0.7(30 Å). A nuclear Bragg peak because of isotopic periodicity is observed at an angle of 0.55°. where the electronic scattering is of the order of 10−3. A nuclear reflectivity of 2.5% has been obtained at the first Bragg peak.
    Download PDF (474K)
  • Masafumi Umekawa, Noriaki Hamada, Akio Kodama, Yutaka Moritomo
    2004 Volume 73 Issue 2 Pages 430-433
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The electronic ground state of RbMnFe(CN)6 is calculated by using all-electron full-potential linearized augmented-plane–wave (FLAPW) method in the local density approximation (LDA).With using the tetragonally distorted structure determined by the x-ray diffraction (XRD) measurement, we obtain the ferromagnetic ground state with the magnetization of 4 μB per chemical formula: the Mn moment is 3.17 μB, and the induced Fe moment is 0.25 μB. The tetragonal symmetry at the Mn site is crucial to obtain the insulating state; the Jahn–Teller splitting is as large as 0.7 eV between the up-spin Mn 3d(z2) and 3d(x2y2). The energy bandgap (0.29 eV) exists between the up-spin Mn 3d(z2) band and the down-spin Mn 3d(xy) band. The result confirms that the electron configurations are the high-spin 3d4 for Mn and the low-spin 3d6 for Fe, which has been suggested by measurements of the magnetic susceptibility and the XRD.
    Download PDF (669K)
  • Isao Maruyama, Naokazu Shibata, Kazuo Ueda
    2004 Volume 73 Issue 2 Pages 434-440
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    With the finite temperature density matrix renormalization group method (FT-DMRG), we have developed a method to calculate thermodynamic quantities and the conductance of a quantum dot system. Conductance is written by the local density of states at the dot. The density of states is calculated with the numerical analytic continuation from the thermal Green’s function which is obtained directly by the FT-DMRG. Typical Kondo behaviors in the quantum dot system are investigated clearly by comparing the conductance with the magnetic and charge susceptibilities: Coulomb oscillation peaks and the unitarity limit. We also discuss the advantage and disadvantage of the present method.
    Download PDF (308K)
  • Masatake Yamaguchi, Motoyuki Shiga, Hideo Kaburaki
    2004 Volume 73 Issue 2 Pages 441-449
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The electronic structures of Σ5(012) symmetrical tilt grain boundary (GB) and (012) free surface (FS) systems for nickel including hydrogen are calculated by the full-potential linearized augmented plane wave method with the generalized gradient approximation. The GB/FS energy and the binding energy of hydrogen at an inner bulk site and GB/FS site are calculated. The calculated binding energy of hydrogen on Ni(111) surface is in good agreement with experiment. The difference of the binding energies between the Σ5(012) GB/FS site and the inner bulk site is obtained as the GB/FS segregation energy, and the difference between GB and FS segregation energies as the embrittling potency energy. The segregation position of hydrogen atom is determined by the force minimization. We find that hydrogen atom prefers Σ5(012) GB to inner bulk energetically by about 0.3 eV/H, while it prefers (012) FS to the GB by about 0.3–0.4 eV/H. The open space at GB may be occupied by an additional interstitial Ni atom since it increases the GB energy by only about 10%. In this case, the GB segregation energy of hydrogen reduces, which makes the segregation difficult. The calculated zero-point energies of hydrogen at inner bulk, GB, and FS sites are within 0.12–0.16 eV/H. The difference of the zero-point energies is within 0.04 eV/H, which is small comparing with the segregation energy and embrittling potency.
    Download PDF (154K)
  • Mitsuaki Takigawa, Masanori Ichioka, Kazushige Machida
    2004 Volume 73 Issue 2 Pages 450-458
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    On the basis of the Bogoliubov–de Gennes theory for the two-dimensional extended Hubbard model, the vortex structure in d-wave superconductors is investigated including the contribution of the induced incommensurate antiferromagnetism around the vortex core. As the on-site repulsive interaction U increases, the spatial structure of charge and spin changes from the antiferromagnetic state with checkerboard modulation to that with the stripe modulation. By the effect of the induced antiferromagnetic moment, the zero-energy density of states is suppressed, and the vortex core radius increases. We also study the effect of the local density of states (LDOS) change on the site-dependent nuclear relaxation rate T1−1(r). These results are compared with a variety of experiments performed on high Tc cuprates.
    Download PDF (890K)
  • Shinpei Fujii, Shoji Ishida, Setsuro Asano
    2004 Volume 73 Issue 2 Pages 459-463
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    To expand our knowledge of Fe2VSi, band calculations (LMTO-ASA) have been performed for paramagnetic (P), ferromagnetic (F) and antiferromagnetic (AF) orderings. The total-energy results show the following facts: AF is the most stable among those orderings; The deformation from cubic to tetragonal structures contributes to the stabilization of AF. These facts were also investigated in terms of “band energy” estimated from DOS. Concerning magnetic moments, those on Fe atoms are slightly enhanced from F to AF. The result for (Fe15⁄16V1⁄16)2(V7⁄8Fe1⁄8)Si indicates the possibility of the existence of Fe atoms with large magnetic moments due to the atomic disorder between Fe and V atoms.
    Download PDF (149K)
  • Minoru Soda, Yukio Yasui, Masafumi Ito, Satoshi Iikubo, Masatoshi Sato ...
    2004 Volume 73 Issue 2 Pages 464-468
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Neutron diffraction studies have been carried out on a single crystal of oxygen-deficient perovskite NdBaCo2O5 in the temperature range of 7–370 K. There have been observed, with decreasing temperature T, two magnetic transitions accompanied with structural changes, to the antiferromagnetic phase at ∼360 K and to the charge ordered antiferromagnetic one at ∼250 K. We have studied the magnetic structures at 300 K and 7 K. At these temperatures the Co-moments have the so-called G-type antiferromagnetic structure, and Co ions are considered to be in the high spin state over the whole temperature range below TN∼360 K.
    Download PDF (335K)
  • Shigeru Takagi, Hideaki Muraoka, Tatsuma D. Matsuda, Yoshinori Haga, S ...
    2004 Volume 73 Issue 2 Pages 469-474
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The microscopic magnetic properties of the itinerant 5f-electron antiferromagnet UGa3 (TN=67 K) have been investigated in the paramagnetic state by means of Ga NQR studies of the two naturally abundant isotopes 69Ga and 71Ga. A striking and unusual increase of the nuclear longitudinal relaxation rate 1⁄T1 has been observed above 230 K, which includes a strong component of nuclear quadrupolar relaxation. Both the magnetic and quadrupolar relaxation rates have been found to increase simultaneously above 230 K. Correspondingly, the NQR frequencies also show a clear deviation from lower-T T3⁄2-dependence above 230 K. These results are discussed in terms of a crossover from lower-T itinerant to higher-T more localized spin fluctuations and associated orbital fluctuations on the part of the U 5f electrons. A mechanism of transferred quadrupole interaction is presented, through which the fluctuations among the U 5f orbitals involve those among the counter-anion Ga 4p orbitals and thereby cause quadrupolar relaxation of the Ga nuclear spins.
    Download PDF (130K)
  • Ae Ran Lim, In Gyoo Kim
    2004 Volume 73 Issue 2 Pages 475-479
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    The phase transitions of a ferroelastic CsPbCl3 single crystal grown by using the Bridgman method have been investigated using 133Cs and 207Pb nuclear magnetic resonance (NMR). Two sets of seven-line 133Cs NMR signals were obtained instead of a simple seven-line structure. From the experimental data, the 133Cs NMR parameters were obtained in the temperature range from phase I to phase IV. These showed the same magnitudes for the quadrupole coupling constants and the asymmetry parameters for the resonance lines of the two sets, but with different orientations. Near the transition temperatures 37°C and 47°C, the NMR parameter of the 133Cs nucleus changed abruptly, which means that first-order phase transitions occurred at 37°C and 47°C, whereas a second-order phase transition occurred at 42°C. In addition, the nuclear spin–lattice relaxation time of the Cs nucleus in this crystal revealed a discontinuity at 47°C while the Pb relaxation time seems to be continuous in the temperature. The abrupt change in the 133Cs relaxation time near 47°C is due to the critical showing down of the soft mode. Our relaxation time results indicate that the phase transitions might be attributed to the dominant relaxation mechanism.
    Download PDF (121K)
  • Keisuke Ohdaira, Kazuo Ono, Kazuhito Uchida, Shinji Koh, Noboru Miura, ...
    2004 Volume 73 Issue 2 Pages 480-484
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Magnetic-field dependence of the photoluminescence (PL) characteristic of type-II quantum dots (QDs) was observed in AlInAs/AlGaAs self-assembled QDs. Parameters of the exciton in this system such as a lateral confining energy, a reduced mass and an average radius estimated from the magnetic-field dependence clearly indicated that type-II excitons with holes confined in QDs and electrons in AlGaAs matrix were formed. The PL intensity change both in the Faraday and Voigt configurations, which was well-explained in terms of the shrinkage of electron and hole wave functions and resulting change of their overlap, indicated that electrons in AlGaAs matrix were bound at the top or the bottom of QDs where holes were trapped. The competition between the increased overlap of electron and hole wave functions and the transition of band alignments from type-I to type-II induced by high magnetic fields was also found to provide an anomalous magnetic field dependence of the PL intensity in a particular sample where many type-I QDs were included.
    Download PDF (469K)
  • Tatsunari Sakurai, Osamu Inomoto, Hidetoshi Miike, Shoichi Kai
    2004 Volume 73 Issue 2 Pages 485-490
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    A surface deformation wave coupled with an oscillatory hydrodynamic flow is observed in a thin solution layer of the Belousov–Zhabotinsky reaction. The observation is carried out with a Mach–Zehnder interferometric system under the excitation of chemical spiral waves in the solution. The surface deformation wave is induced spontaneously at the end of a dish. It propagates towards the center of the spiral waves, and disappears there. This fact leads to understand the oscillatory flow as a propagating convection waves having long-scale surface deformation. The Marangoni effect or surface tension driven convection with deformable surface plays an important role to establish the oscillatory flow.
    Download PDF (305K)
  • Hiroshi Nakagawa, Hironari Kamikubo, Itaru Tsukushi, Toshiji Kanaya, M ...
    2004 Volume 73 Issue 2 Pages 491-495
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Dynamical heterogeneity of a protein, staphylococcal nuclease, was studied using incoherent elastic neutron scattering at various temperatures. The elastic scattering intensity profile at low q region can be approximated with a Gaussian function, while the deviation from the function becomes remarkable at higher q-region. We analyzed the non-Gaussianity in terms of protein dynamical heterogeneity. Three typical distribution, Gaussian, bimodal, and exponential distribution, were applied to the data analysis to obtain the average mean square displacement and the width of distribution. The analysis showed that the non-Gaussianity comes partly from dynamical heterogeneity and that a bimodal distribution is adequate for quantitative analysis.
    Download PDF (115K)
  • Chiaki Uyeda, Kenta Tanaka, Ryoichi Takashima
    2004 Volume 73 Issue 2 Pages 496-497
    Published: February 15, 2004
    Released on J-STAGE: July 25, 2007
    JOURNAL RESTRICTED ACCESS
    Download PDF (67K)
feedback
Top