巻号一覧
72 巻, 3 号
選択された号の論文の51件中1～50を表示しています
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Takuya Kohno, Fujio Shimizu, Jun-ichi Fujita, Kazuko Shimizu2003 年 72 巻 3 号 p. 461-463
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありA double slit atom interferometer with a reflective double slit that is formed on a flat silicon surface is demonstrated. The result shows that quantum reflection is a promising mechanism to construct stable highly accurate atom-optical devices.抄録全体を表示PDF形式でダウンロード (172K) -
Yi-Xiong Shen, Ling-Ti Kong, Hao-Ran Gong, Wen-Sheng Lai, Bai-Xin Liu2003 年 72 巻 3 号 p. 464-467
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありA realistic many-body potential based on the embedded atom method is derived for an equilibrium immiscible Cu–V system by fitting some physical properties of the nonequilibrium B2 CuV and L12 Cu3V phases determined by ab initio calculations. With the constructed potential, the total energies and the lattice constants of not only the B2 CuV and L12 Cu3V, but also the B1 CuV and D019 hcp Cu3V phases were reproduced/calculated and were in good accordance with those obtained from ab initio calculations.抄録全体を表示PDF形式でダウンロード (97K) -
Hiromi Taniguchi, Masashi Miyashita, Kenichi Uchiyama, Kazuhiko Satoh, ...2003 年 72 巻 3 号 p. 468-471
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe demonstrate that an organic Mott insulator, β′-(BEDT-TTF)2ICl2, is metallized by application of extremely high pressure by means of the cubic anvil press. When the metallic state is stabilized, superconductivity with the highest transition-temperature (Tc) among the organic systems appears. The lower limit of the pressure at which the superconducting transition manifests itself is approximately 7.0 GPa and Tc reaches a maximum value, 14.2 K (onset), at 8.2 GPa. The pressure-temperature phase diagram is constructed and discussed in terms of the comparison with those of other organic systems.抄録全体を表示PDF形式でダウンロード (172K) -
Yukitoshi Motome, Nobuo Furukawa2003 年 72 巻 3 号 p. 472-475
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありSpin excitation spectrum is studied in the double-exchange model with randomness. Applying the spin wave approximation and the spectral function analysis, we examine excitation energy and linewidth using analytical as well as numerical methods. For a small wave number q∼0, the excitation energy is cosine-like and the linewidth shows q-linear behavior. This indicates that the spin excitation becomes incoherent or localized near q=0. Crossover takes place to the marginally coherent regime where both the excitation energy and the linewidth are proportional to q2. The incoherence is due to local fluctuations of the kinetic energy of electrons. Comparison with experimental results in colossal magnetoresistance manganites suggests that spatially-correlated or mesoscopic-scale fluctuations are more important in real compounds than local or atomic-scale ones.抄録全体を表示PDF形式でダウンロード (121K) -
Kiyohide Nomura2003 年 72 巻 3 号 p. 476-478
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありIn quantum spin chains, it has been observed that the incommensurability occurs near valence-bond-solid (VBS)-type solvable points, and the correlation length becomes shortest at VBS-type points. In addition, the correlation function decays purely exponentially at VBS-type points, in contrast with the two-dimensional (2D) Ornstein-Zernicke type behavior in other regions with an excitation gap. We propose a mechanism to explain the onset of the incommensurability and the shortest correlation length at VBS-like points. This theory can be applied to more general cases.抄録全体を表示PDF形式でダウンロード (73K) -
Kouichi Okunishi, Takashi Tonegawa2003 年 72 巻 3 号 p. 479-482
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe determine the magnetic phase diagram of the S=1⁄2 antiferromagnetic zigzag spin chain in the strongly frustrated region, using the density matrix renormalization group method. We find the magnetization plateau at 1⁄3 of the full moment accompanying the spontaneous symmetry breaking of the translation, the cusp singularities above and/or below the plateau, and the even–odd effect in the magnetization curve. We also discuss the formation mechanisms of the plateau and cusps briefly.抄録全体を表示PDF形式でダウンロード (164K) -
Shigeru Takagi, Daisuke Maruta, Hiko-ichiro Sasaki, Hiroshi Uozaki, Hi ...2003 年 72 巻 3 号 p. 483-486
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe microscopic magnetic properties of superconducting (TC≅6 K) λ-(BETS)2GaCl4 (BETS = bis(ethylenedithio)tetraselenafulvalene) have been investigated by 77Se NMR in the normal state between 7.1 and 100 K on randomly oriented single crystals with κ-(BETS)2GaCl4 as a reference compound. From the T-dependences of the Knight shift and the linewidth, the intrinsic uniform susceptibility χq=0(T) has been found to decrease with decreasing T below 30 K for λ-(BETS)2GaCl4. Nevertheless, 1⁄(T1T) does not show any corresponding decrease but is constant down to the lowest T, which indicates increasing contributions with decreasing T from antiferromagnetic spin fluctuations. The Knight shift and 1⁄(T1T) have been analyzed quantitatively and the enhancement factor K(α)>1 is deduced in the low-T limit. On the basis of these results, the development of antiferromagnetic spin fluctuations of π-electrons at low T is concluded for λ-(BETS)2GaCl4.抄録全体を表示PDF形式でダウンロード (115K) -
Hirokazu Fukuda, Hikaru Nagano, Shoichi Kai2003 年 72 巻 3 号 p. 487-490
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありNoise-induced synchronization was investigated in a large number of chemical oscillators coupled to each other in the photosensitive Belousov–Zhabotinsky (BZ) reaction system. The oscillator consisted of an ionic bead for absorbing catalyst ions and the reaction occurred only on it. We studied two different synchronization systems: a two-oscillator system for investigating the fundamental features of noise synchronization dynamics and a multiple-oscillator system in which the oscillators are coupled in a lattice arrangement for studying group synchronization by noise. The synchronization rate depended on the distance between chemical oscillators. By increasing the noise intensity, the number of synchronized oscillators increased and showed a maximum at a certain optimum noise intensity. That is, stochastic synchronization in BZ reaction was clearly observed in the spatially discrete distribution system.抄録全体を表示PDF形式でダウンロード (93K) -
Hang-yu Ruan, Yi-xin Chen2003 年 72 巻 3 号 p. 491-495
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありStarting from a two line soliton solution of an integrable (2+1)-dimensional equation in bilinear form, one can find a dromion solution, that is localized in all directions, for the physical field and/or the suitable potential (the physical field’s derivatives). The interaction properties between two dromions are studied both analytically and numerically for (2+1)-dimensional KdV-type equations. Our analysis shows that the shape of dromions after interaction may be changed or unchanged for different form of solutions.抄録全体を表示PDF形式でダウンロード (263K) -
H. J. Shin2003 年 72 巻 3 号 p. 496-500
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe present 2+1 dimensional soliton equations of inhomogeneous type which are derived systematically using the covariance with respect to the Darboux transformation. By setting Darboux invariants to be explicit functions of space–time, we obtain nonlinear equations describing soliton propagation in media with inhomogeneities. Darboux covariant equations obtained here include the inhomogeneously generalized Davey–Stewartson equation, the 2+1 dimensional modified Korteweg–de Vries equation and other binary Darboux covariant equations of inhomogeneous type.抄録全体を表示PDF形式でダウンロード (96K) -
Kiyonobu Nagaya2003 年 72 巻 3 号 p. 501-508
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありIn order to realize a new idea for the size-selective structural analysis of neutral free clusters [Yao et al.: J. Synchrotron Radiat. 8 (2001) 542], we have developed an experimental method in which the photoelectron photoion coincidence (PEPICO) spectra are measured synchronously with the extended X-ray fine structure (EXAFS). In this method we can measure not only the total ion yield (TIY) but also the partial ion yield (PIY) of each daughter ion which stems from the fragmentation of neutral clusters induced by the X-ray absorption. We have applied this method to selenium cluster beam and found that both the TIY and PIY spectra show clear EXAFS oscillations, from which structural information on Se2 and larger species such as Se5 have been deduced.抄録全体を表示PDF形式でダウンロード (238K) -
Jin-Seok Jeon, Jung-Yeop Lee, Ho-Young Kwak2003 年 72 巻 3 号 p. 509-515
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありPossibility of upscaling for single bubble sonoluminescence by reducing the driving frequency was tested experimentally. The maximum bubble radius and the expansion ratio obtained from an air bubble at a driving frequency of 12.926 kHz and driving amplitude of 1.33 atm at a water temperature of 23.5°C are considerably less than the predicted ones by the Rayleigh–Plesset equation so that the upscaling of SL cannot be achieved very much with this method. Observed bubble behavior under ultrasonic field may be explained as “relaxation motion” of a gas bubble to the characteristic time of the applied ultrasound.抄録全体を表示PDF形式でダウンロード (206K) -
Hideshi Hanazaki2003 年 72 巻 3 号 p. 516-525
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありNonlinear waves in a rotating fluid passing through a long circular tube are studied numerically. The waves are resonantly excited by a local undulation of the tube wall. We consider a swirl of Burgers-vortex type which would be typical in the experiments and has often been used in a theoretical model of vortex breakdown. We show that the forced Korteweg–de Vries (fKdV) equation, which has been derived under the assumption of weak nonlinearity, describes well the time development of nonlinear waves even when the amplitude is large enough to form recirculation eddies on the tube axis. Each eddy is embedded in each crest of the solitary wave. This extends the previous results for steady flows that the \\mathopsech\\ olimits2-type solution of the steady KdV equation can be applied to an inertial wave which sustains a recirculation eddy. It is found that, because of the form of modal eigenfunction for the Burgers vortex, the axial flow reversal first occurs almost inevitably on the tube axis. The recirculation eddy or axial flow reversal appears even when the amplitude of the wave governed by the fKdV equation is still small enough so that the assumption of weak nonlinearity is valid.抄録全体を表示PDF形式でダウンロード (270K) -
Mehrdad Kashani2003 年 72 巻 3 号 p. 526-532
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe influence of the cathode structure on the focus discharges in a 7 kJ Mather-type plasma focus device was investigated by using two types of cathode electrodes, 1) bar and 2) tubular cathodes. In the present experimental results that were obtained under optimized conditions except the cathode structure, the cathode structure had a great influence on energy dissipation in the run-down phase and hence the neutron yield. The energy dissipation in the run-down phase was much lower in the bar cathode than in the tubular one and as a result, the pinch current and the neutron yield were higher in the bar cathode. The experimental results obtained by many authors using both cathodes do not seem to support our experimental results. However, they were obtained in different devices with the bar or tubular cathode. It seems that for a complete comparison it is necessary to investigate both types of cathode in the same device under optimized experimental conditions.抄録全体を表示PDF形式でダウンロード (198K) -
Chi-Chuan Hwang, Jee-Gong Chang, Shin-Pon Ju, Ming-Horng Su2003 年 72 巻 3 号 p. 533-544
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありMolecular dynamics simulation is used to investigate dynamic impact behavior at the nanoscale. The classic many-body tight-binding potential is employed to model the atomic force acting between atoms. The impact model of a Cu sphere cluster hitting a Cu substrate is established. Investigated issues include dynamic cluster/substrate interactions, substrate deformation, substrate fracture characteristics, force transmission, energy transformation between cluster and substrate, cluster motion characteristics, debris cloud formation characteristics, and the characteristics of the dynamic impact behavior at different cluster incident energies. The results show that an elastic necking phenomenon behavior is found for the case of clusters landing at the relatively low incident energy of 0.1 eV/atom. The phenomenon of impact hole recovery, which is the result of interatomic attractive forces applied by the substrate on the cluster atoms, is observed at an incident energy of 2 eV. In this situation, the cluster atoms join those of the substrate. At the higher incident energies of 5 and 50 eV, a significant number of the substrate atoms dissociate themselves from the substrate structure and form a debris cloud. Additionally, it is determined that unlike lower incident energy impacts, substrate deflection does not occur immediately upon cluster penetration of the substrate for elevated incident energies. Finally, it is found the substrate removal rate is a key factor in determining the distribution density of the debris cloud.抄録全体を表示PDF形式でダウンロード (948K) -
Masaru Sugiyama, Kuniaki Goto2003 年 72 巻 3 号 p. 545-550
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありMicroscopic basic equations for analyzing nonequilibrium phenomena in three-dimensional anharmonic crystal lattices at finite temperatures are self-consistently derived from the Liouville equation by adopting both independent particle approximation and Gaussian approximation. The model prescribed by the basic equations can be regarded as the dynamical version of the self-consistent Einstein model, and is valid in a wide temperature range including the melting point. Thermal equilibrium states of several fcc and bcc crystals are also analyzed by using the basic equations. Singularities in the temperature dependences of the nearest-neighbor distance and the amplitude of thermal vibration at the melting point are found, and Lindemann’s law is examined. The results obtained here will be utilized in the analyses in the following papers of the present series.抄録全体を表示PDF形式でダウンロード (146K) -
Mirza M. Shamim, Takeo Ishidate, Kikuo Ohi2003 年 72 巻 3 号 p. 551-555
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありHigh pressure Raman spectra of KNbO3–KTaO3 (KTN) and –NaNbO3 (KNN) mixed crystals have been measured to study the behavior of the anomalous mode coupling as well as the phase transition and analyzed on the basis of the two-mode coupling model. The anomalous mode coupling has been observed for all samples under pressure. The mode coupling was observed without compression for K(TaxNb1−x)O3 crystals with x more than 40%. The upper B1(TO) mode frequency of these coupling modes decreased with increase of Ta concentration for the KTN crystals, but remained constant independent of the Na concentration for the KNN crystals. Further, Ta doping plays an equivalent role to the pressure effect with respect to the upper B1(TO) mode.抄録全体を表示PDF形式でダウンロード (135K) -
Satoshi Kawaguchi, Tomohiro Onda2003 年 72 巻 3 号 p. 556-568
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありPhase transitions including ones to the amorphous state are studied based on the phase field model and the heat diffusion equation. Two order parameters are introduced to describe the three different phases. There is a Lyapunov function with three local minima corresponding to the liquid, crystal and amorphous phases. The simplest interaction term is assumed, and the energy barriers between the states control the transition rate. Although the energy level of amorphous phase is higher than the crystal phase one, the amorphous phase cannot change into the crystal without the thermal noise due to the energy barrier. The key point of the present model is that phase transitions depend on not only the temperature but also the cooling rate. Rapid cooling leads to the amorphous phase below the melting temperature, whereas slow cooling leads to the crystal phase. With this simple model, the phase transitions are investigated by simulations. There is a kink solution connecting the crystal phase with the liquid or amorphous phase; it travels with a speed that is dependent on the temperature at the interface. The stabilities of different phases are compared when they are in collision. Although the kink solution is stable, the planar solution in two dimensions is destabilized through lateral inhibition. This result is theoretically supported by the stability analysis of the interface. A crystallization from a super-cooled liquid induced by noise is observed in the case of slow cooling. The crystallization occurs without a fixed seed and suggests that the present system is a good candidate for the present phase transitions.抄録全体を表示PDF形式でダウンロード (210K) -
Kazutaka Kudo, Takashi Noji, Yoji Koike, Takuo Sakon, Mitsuhiro Motoka ...2003 年 72 巻 3 号 p. 569-575
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe have measured the magnetic susceptibility in a magnetic field of 1 T (rotating the field direction) in the bc plane, the magnetization curve in magnetic fields up to 30 T and the thermal conductivity in magnetic fields up to 14 T for the quasi-two-dimensional spin system Cu3B2O6. Two-fold symmetry of the susceptibility in the bc plane has been found to develop at low temperatures below the Néel temperature TN=10 K. This is understood on the basis of the low symmetry of the Cu–O–Cu network. The susceptibility does not appear to vanish as T→0 K even in the direction where the magnetization exhibits the minimum, indicating that the spin arrangement in the bc plane at T<TN is noncollinear. The magnetization curve exhibits a bend and/or a jump associated with either spin–flop or metamagnetic transition at T<TN, depending on the field direction. The thermal conductivity along the direction where the magnetization exhibits the minimum in the bc plane has been found to exhibit marked enhancement and a peak at T<TN, which is understood to be caused by the increase of the thermal conductivity due to magnons. The peak is suppressed with increasing magnetic-field below 12 T and tends to recover in high field above 12 T. It has been found that the thermal conductivity strongly correlates with the spin state in Cu3B2O6.抄録全体を表示PDF形式でダウンロード (304K) -
Shugo Ikeda, Yoshihumi Tokiwa, Yoshinori Haga, Etsuji Yamamoto, Tomoyu ...2003 年 72 巻 3 号 p. 576-581
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe have carried out the de Haas–van Alphen (dHvA) experiment to clarify the Fermi surface property of an antiferromagnet UPtGa5, and have constructed the magnetic phase diagram from the high-field magnetization measurement. From the dHvA experiment, the Fermi surface is found to consist of four kinds of nearly cylindrical Fermi surfaces along the tetragonal [001] direction, which are approximately explained by the result of the spin-polarized energy band calculations based on the antiferromagnetic structure with a sequence of (↑ ↓) along [001]. Relatively large cyclotron masses are detected for carriers of the corresponding Fermi surfaces, ranging from 10 to 24 m0 (m0: rest mass of an electron). 5f electrons are thus concluded to be itinerant and also to contribute to the magnetic moment at the uranium sites.抄録全体を表示PDF形式でダウンロード (921K) -
Kazuhiro Marumoto, Kazuya Soda, Shin-ichi Kuroda, Yutaka Moritomo2003 年 72 巻 3 号 p. 582-587
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありESR studies have been performed on single crystals of layered-perovskite manganites R0.5Sr1.5MnO4 (R = La, Nd). An anisotropic ESR signal with extremely broad linewidth is observed and ascribed to the single-ion-anisotropic D term. For La0.5Sr1.5MnO4, the spin susceptibility χs deviates from the Curie–Weiss-like behavior and the peak-to-peak linewidth ΔHpp shows a broad maximum at the charge-ordering temperature Tco (≈217 K). With further decrease of temperature below 160 K, χs decreases and ΔHpp increases rapidly due to the spin order at the Néel temperature TN (≈110 K). These anomalies are absent in Nd0.5Sr1.5MnO4, which does not show the charge-ordering nor the spin-ordering. On the basis of these experimental data, we will discuss the charge and spin order of La0.5Sr1.5MnO4.抄録全体を表示PDF形式でダウンロード (204K) -
Hiroyoshi Momida, Tamio Oguchi2003 年 72 巻 3 号 p. 588-593
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありSurface properties of antiferromagnetic MnO(001) and NiO(001) are investigated by means of first-principles electronic structure calculations. It is shown that the surface O sites have finite spin magnetic moments of 0.04 μB and 0.07 μB for MnO and NiO surfaces, respectively. Because of non-zero energy gap even at the surface, the spin magnetic moment of Mn and Ni sites are almost the same as those in bulk. At the surface O sites, calculated spin density shows asymmetric distribution comparing with that of the bulk. These results are explained in detail from calculated partial density of states. By surface structural optimization, stable surface structure of O inward rumpled relaxation is obtained for both monoxides.抄録全体を表示PDF形式でダウンロード (200K) -
Junji Yoshida, Tomi Ohtsuki2003 年 72 巻 3 号 p. 594-598
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe have studied quantum transports in two dimensional electron gas (2DEG) numerically, where magnetic fields with sine-type modulation are applied perpendicular to the plane of 2DEG. Due to the non-homogeneous magnetic fields, the system becomes chaotic. We use tight-binding model and investigate the energy level statistics and the two terminal conductance. Depending on the spatial symmetry of the magnetic fields, the system belongs to the unitary class or the orthogonal, which is reflected by the energy level statistics. Attaching leads further destroys the symmetry, and the universal conductance fluctuation for the unitary class is observed. The fractal behavior of the magnetoconductance is also observed.抄録全体を表示PDF形式でダウンロード (155K) -
Yukinobu Kakutani, Yasunori Kubo, Akihisa Koizumi, Nobuhiko Sakai, B. ...2003 年 72 巻 3 号 p. 599-606
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありExperimental and theoretical directional magnetic Compton profiles (MCP’s) of hcp-Co, fcc-Fe50Ni50 and fcc-Ni are compared with each other to elucidate the difference of the electronic structures of magnetic electrons between fcc-Fe50Ni50 (almost equivalent to fcc-Co) and hcp-Co, and between fcc-Fe50Ni50 and fcc-Ni. Small difference is found experimentally in the former case along the corresponding crystalline axes in a region pz<2 au. The difference is isotropic in shape between these crystals, which can be ascribed to the difference of the spin polarization of mainly s-like electron. In the later case, the experimental main difference is theoretically explained with the d-like 4-th and the d-like 5-th band MCP’s. Anisotropies of the MCP in Co are experimentally confirmed for the first time. Limitation of the theoretical calculation based on the single particle approximation is suggested.抄録全体を表示PDF形式でダウンロード (946K) -
Atsushi Yamasaki, Takeo Fujiwara2003 年 72 巻 3 号 p. 607-610
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe quasiparticle band structures of 3d transition metals, ferromagnetic Fe, Ni and paramagnetic Cu, are calculated by the GW approximation. The width of occupied 3d valence band, which is overestimated in the LSDA, is in good agreement with experimental observation. However the exchange splitting and satellite in spectra are not reproduced and it is required to go beyond the GW approximation. The effects of static screening and dynamical correlation are discussed in detail in comparison with the results of the static COHSEX approximation. The dynamical screening effects are important for band width narrowing.抄録全体を表示PDF形式でダウンロード (412K) -
Masahiro Yamazaki, Norikazu Tomita, Keiichiro Nasu2003 年 72 巻 3 号 p. 611-617
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe have theoretically studied various one-dimensional half-filled Hubbard models from weak correlation cases to strong ones, and calculated the Lehmann spectra of the momentum-specified one-body Green’s functions, as well as the total density of states (DOS), using the quantum Monte Carlo method. In the region of intermediate correlation strength, we have found the DOS has new characteristic peaks near the Fermi level, in addition to the well-known upper and lower Hubbard-band peaks. We show these new peaks near the Fermi level come from quasi-coherent states, while the upper and lower Hubbard-band peaks come from strongly incoherent ones. This multi-peaked structure, appearing only in the intermediate region, is shown to be quite insensitive to the dimensionality. Finally, we compare our results with the static single impurity model, and give a rough and intuitive explanation for the origin of this newly obtained multi-peaked structure. Our results also qualitatively agree with the recent experiments on CaVO3 and SrVO3 crystals.抄録全体を表示PDF形式でダウンロード (265K) -
Yusuke Wakabayashi, Youichi Murakami, Ichiro Koyama, Tsuyoshi Kimura, ...2003 年 72 巻 3 号 p. 618-626
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありCharge and orbital ordering behaviors in the half doped bi-layered compound LaSr2Mn2O7 have been studied by resonant and non-resonant x-ray scattering. Three different order parameters, which correspond to the A-type antiferromagnetism, charge ordering and orbital ordering, were observed by measuring the magnetostriction and the superlattice peaks characterized by wavevectors (\\frac12\\frac120) and (\\frac14\\frac140), respectively. The superlattice reflections indicating the charge and orbital ordered states were observed below 210 K. Both the intensities reach a maximum at 160 K on cooling and become very weak below 100 K. The peak width of the charge ordered state agrees with that of the orbital ordered state at all temperatures studied. These results indicate that both the states originate from a single phase and that the charge/orbital ordered islands with definite interfaces disperse in the A-type antiferromagnetic phase. The dimensionality of the charge/orbital ordered phase is discussed using this model.抄録全体を表示PDF形式でダウンロード (289K) -
Eerdunchaolu Bao, J. L. Xiao2003 年 72 巻 3 号 p. 627-633
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありIn this paper, the temperature dependence of the properties of polaron, which is weakly coupled with bulk LO phonons and strongly coupled with SO phonons, in a slab of polar crystal is studied by means of a modified second LLP transformation for the first time. An expressions for the self-trapping energy and the effective mass of the polaron in a slab of polar crystal as a function of the temperature and slab thickness are derived by using a linear combination operator and two modified LLP variational method. Our numerical results of the self-trapping energy and the effective mass for KCl show that the polaron self-trapping energy and effective mass in a polar crystal are strongly related to the slab thickness and the temperature. The self-trapping energy and the effective mass will decrease with increasing slab thickness and temperature.抄録全体を表示PDF形式でダウンロード (120K) -
Yasusi Koyama, Yositake Takane2003 年 72 巻 3 号 p. 634-644
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe study quantum interference corrections to the conductance of a thin wire of a disordered ferromagnetic metal in the presence of a domain wall (DW). The DW is a source of the decoherence of electron wavefunctions. We calculate the weak-localization correction and the mesoscopic conductance fluctuations to show how the DW suppresses these quantum corrections. We explicitly take the location of the DW into account in calculating the quantum corrections. It is shown that the magnitude of the quantum corrections depends on the location of the DW when the system length is of the order of, or shorter than, the phase coherence length. We find that the quantum interference corrections are most remarkably suppressed when the DW is located at the center of the ferromagnetic wire. It is also shown that the decoherence effect becomes pronounced with decrease of the thickness of the DW.抄録全体を表示PDF形式でダウンロード (214K) -
Hirofumi Watanabe, Tohru Kawarabayashi, Yoshiyuki Ono, Tomi Ohtsuki2003 年 72 巻 3 号 p. 645-649
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありElectron transport in a two-dimensional symplectic system with time-dependent perturbations is investigated numerically by the equation of motion method. The effect of time-dependent perturbations on the conductivity is examined in the critical regime as well as in the metallic regime. The universal correction to the conductivity, which is consistent with the weak localization theory, is indeed observed in the metallic regime. In the critical regime, it is found that the dependence of the conductivity on the frequency of perturbations can be described by the one-parameter scaling.抄録全体を表示PDF形式でダウンロード (179K) -
Shin-ichiro Kondo, Kosaku Yamada2003 年 72 巻 3 号 p. 650-658
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe examine the transition probability in the neutralizing process of +2 ion such as Be+2, Ca+2 and Ba+2 through the electron transfer between the ion and a metal surface, using an impurity Anderson Hamiltonian. Within second order perturbation theory with respect to the transfer integral, an analytical expression of the transition probability is derived and numerically calculated. From the numerical results, the neutralization process of +2 ion on the metal surface seems to occur more easily with decreasing the atomic number of an ion. The transition probability depends on not only the initial kinetic energy of the moving ion but also its species of ions. In addition, the plot of the transition probability as a function of the initial velocity of ions theoretically suggests the presence of an optimized initial velocity for the neutralization process. From the contour map of the transition probability plotted as functions of energy difference Ea−EF (Ea: energy of localized electron, EF: Fermi energy) and intra Coulomb potential U, we can see that the neutralization process of Be+2 easily occurs in the range of Ea−EF being from −0.8 eV to −1.2 eV and U being from 0.5 eV to 0.7 eV, when the initial kinetic energy is 100 eV. The plot for various U shows that the transition probability almost vanishes when U=0.0 eV. This seemingly contradictory result arises from the fact that for small U the transition matrix element cancels in the second-order process as a result of the energy conservation.抄録全体を表示PDF形式でダウンロード (268K) -
Senku Tanaka, Sam Dylan Moré, Kazutoshi Takahashi, Masao Kamada2003 年 72 巻 3 号 p. 659-663
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありCore-level photoelectron spectroscopy with the combination of synchrotron radiation and laser light was used for exploring the dynamics of the surface photovoltage (SPV) effect on a p-GaAs (100). It was found that a temporal profile of the SPV is very different in microsecond range between room temperature and 90 K. The results can be explained with the recombination of photoexcited carriers via thermionic and tunneling processes. The SPV effects and its temporal profiles on the negative electron-affinity (NEA) surface were also studied. It was observed that the SPV effect is suppressed on the NEA surface, which may be due to the escape process of the photoexcited carriers.抄録全体を表示PDF形式でダウンロード (207K) -
Naokazu Shibata, Daijiro Yoshioka2003 年 72 巻 3 号 p. 664-672
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe ground state of 2D electrons in high magnetic field is studied by the density matrix renormalization group method. The ground state energy, excitation gap, and pair correlation functions are systematically calculated at various fillings in the lowest and the second lowest Landau levels. The ground state phase diagram, which consists of incompressible liquid state, compressible liquid state, stripe state, pairing state, and Wigner crystal is determined.抄録全体を表示PDF形式でダウンロード (263K) -
Youichi Yanase, Masao Ogata2003 年 72 巻 3 号 p. 673-687
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありTriplet superconductivity in Sr2RuO4 is investigated with main interest on its internal degree of freedom. We perform a microscopic calculation to investigate how the chiral state \\hatd(k)=(kx±iky)\\hatz is realized among the underlying six degenerate states. Starting from the three band Hubbard model with spin–orbit interaction, we use a perturbation theory in order to calculate the pairing interaction. The p-wave superconductivity with Tc∼1.5 K is obtained in the moderately weak coupling region. It is shown that the orbital dependent superconductivity (ODS) robustly appears in Sr2RuO4. We determine the stabilized state by solving the Eliashberg equations. We find that the Hund coupling term as well as the spin–orbit interaction is necessary for the “symmetry breaking interaction”. The main result is that the chiral state is stabilized in case of the p-wave symmetry with the main γ-band, which is obtained in the perturbation theory. When we assume the other pairing symmetry including the f-wave state, the symmetry breaking interaction gives the other d-vector. The electronic structure constructed from the t2g-orbitals is essential for this result.抄録全体を表示PDF形式でダウンロード (766K) -
Random Magnetism in S=1⁄2 Heisenberg Chains with Bond Alternation and Randomness on the Strong BondsKazuo Hida2003 年 72 巻 3 号 p. 688-693
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe S=1⁄2 Heisenberg chains with bond alternation and randomness on the strong bonds are studied by the density matrix renormalization group method. It is assumed that the odd-th bond is antiferromagnetic with strength J and even-th bond can take the values JA and JF (JA>J>0>JF) randomly. The ground state of this model interpolates between the Haldane and dimer phases via a randomness dominated intermediate phase. Based on the scaling of the low energy spectrum and mean field treatment of the interchain coupling, it is found that the magnetic long range order is induced by randomness in the intermediate regime. In the magnetization curves, there appears a plateau at the fractional value of the saturated magnetization. The fine structures of the magnetization curves and low energy spectrum are understood based on the cluster picture. The relation with the recent experiment for (CH3)2CHNH3Cu(ClxBr1−x)3 is discussed.抄録全体を表示PDF形式でダウンロード (231K) -
Masashi Fujisawa, Jun-Ichi Yamaura, Hidekazu Tanaka, Hiroshi Kageyama, ...2003 年 72 巻 3 号 p. 694-697
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe crystal structure of Cu2Cl4·H8C4SO2 was analyzed by single-crystal X-ray diffraction. This compound consists of the double chain of the edge-sharing octahedra CuCl5O. With decreasing temperature, the magnetic susceptibility decreases steeply toward zero below 10 K after exhibiting a broad maximum at 65 K, which is characteristic of the one-dimensional antiferromagnet. The magnetic properties of the present system can be described by the double spin chain model with dominant exchange interactions along the leg. The observed small excitation gap Δ⁄kB≈5.8 K is attributed to the weak exchange alternation along the leg or the weak zig-zag rung interactions. The magnetization curve measured at 1.3 K for the magnetic field parallel to the c-axis shows a discontinuous jump at Ht≈22.8 T indicative of the phase transition of the first order.抄録全体を表示PDF形式でダウンロード (313K) -
Shinpei Fujii, Youichi Ienaga, Shoji Ishida, Setsuro Asano2003 年 72 巻 3 号 p. 698-704
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありTo expand our knowledge of Fe2+xV1−xZ (Z = Al, Ga), band calculations (LMTO-ASA) have been performed for several x values (x=0,±0.125,±0.25) with a supercell method. Obtained density of states and magnetic moments indicate that excess atoms, which are introduced instead of the original Fe or V atom in Fe2VZ, bring a drastic change in electronic and magnetic properties of Fe2VZ. The existence of those atoms causes the collapse of the gap (or pseudogap) and the change from nonmagnetic to magnetic states. In the magnetic state, those atoms carry 2.5–2.6μB for x>0 and 0.7–1.1μB for x<0.抄録全体を表示PDF形式でダウンロード (266K) -
Makoto Yoshida, Keiichi Koyama, Paul C. Canfield, Charles Cunningham, ...2003 年 72 巻 3 号 p. 705-708
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありCyclotron resonance (CR) measurements on a single crystal of PrSb have been performed at temperatures between 1.5 K and 20 K in the frequency range from 50 to 110 GHz. Three CR absorption lines are observed at low temperatures. For magnetic fields parallel to the [001] direction, the determined effective masses are 0.25m0, 0.3m0, and 0.53m0, respectively. In addition to “normal” CR, we have observed Doppler-shifted cyclotron resonance which shows nonlinear behavior on the frequency–field diagram.抄録全体を表示PDF形式でダウンロード (174K) -
Neutron Structural analysis of La1−xSrxMnO3 —Variation of One-Electron Bandwidth W with Hole Doping—Sheng Xu, Yutaka Moritomo, Kenji Ohoyama, Arao Nakamura2003 年 72 巻 3 号 p. 709-712
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありWe have performed neutron powder diffraction measurements for La1−xSrxMnO3 (x=0.00–0.20) at room temperature. We have found that the crystal structure is orthorhombic (Pbnm, Z=4; O) at x≤0.14 and rhombohedral (R\\bar3c, Z=2; R) at x≥0.18, respectively. At this structural phase transition, the averaged Mn–O–Mn bond angle ⟨θ⟩ discontinuously increases from 160.8° at x=0.14 to 163.5° at x=0.18. We have estimated relative variation of the one-electron bandwidth W of the eg-band, and discussed the insulator-metal behavior induced by hole doping.抄録全体を表示PDF形式でダウンロード (160K) -
Yorihiko Tsunoda, Daisuke Tsuchiya, Yasuyuki Higashiyama2003 年 72 巻 3 号 p. 713-717
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありMagnetic structures of Pt100−XFeX (X=16, 18, 24 and 25) alloys were studied by means of neutron elastic and inelastic scattering. Non-collinear antiferromagnetic structure is experimentally verified for the ground state of the stoichiometric alloy Pt3Fe. The antiferromagnetic phase transition below TN in Pt3Fe alloy is considered to be one of the crossover points of the antiferromagnetic spin correlations which show successive change towards the original point of the reciprocal lattice with increasing Fe concentration in the wide concentration range of the Pt–Fe system.抄録全体を表示PDF形式でダウンロード (160K) -
Ae Ran Lim, Hee Won Shin2003 年 72 巻 3 号 p. 718-722
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証あり133Cs (I=7⁄2) nuclear magnetic resonance in a Cs2CoCl4 single crystal grown by using the slow evaporation method was measured in the two mutually perpendicular crystal planes. The 133Cs resonances of two different groups, respectively, with two crystallographically inequivalent cesium nuclei, Cs(I) and Cs(II) in the unit cell, were recorded. From their angular dependences, the Cs(I) and the Cs(II) nuclei have different values for the quadrupole coupling constant and the asymmetry parameter. The quadrupole coupling constant and the asymmetry parameter obtained for Cs(I) with a smaller separation were e2qQ⁄h=725 kHz and η=0.58. Those for Cs(II) with a larger separation were e2qQ⁄h=802 kHz and η=0.85. The electric field gradient (EFG) tensors of Cs(I) and Cs(II) are asymmetric, and the orientations of their principal axes do not coincide. The Cs(I) ion surrounded by 11 chlorine ions has a small quadrupole parameter and is high in symmetry. The Cs(II) ion surrounded by 9 chlorine ions has a larger quadrupole parameter and is lower in symmetry than the Cs(I) ion. In addition, the spin–lattice relaxation time for 133Cs was decreased with increasing temperature in the temperature range from 180 to 400 K. The relaxation behavior of Cs(I) and Cs(II) can be explained by the direct process of scattering from a single phonon.抄録全体を表示PDF形式でダウンロード (121K) -
Jun Goto, Minoru Tanigaki, Akihiro Taniguchi, Yoshitaka Ohkubo, Yoichi ...2003 年 72 巻 3 号 p. 723-726
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありNuclear magnetic resonance on oriented nuclei (NMR-ON) of La existing as a dilute impurity in Fe was observed for the first time. NMR-ON experiments were performed by detecting the 1596 keV γ rays from the β decay of 140La in external magnetic fields of 0.1, 0.2, 0.4 and 0.6 T. From the external magnetic-field dependence of the resonance frequency, the magnetic hyperfine field and the Knight shift were deduced to be Bhf=−47±1 T and K=−4.0±3.4%, respectively. The effective relaxation time of 140LaFe at 8 mK in an external magnetic field of 0.2 T was determined to be 8.8±1.5 min using a single-exponential fit. The present value of the magnetic hyperfine field agrees with that deduced from a two-site model by the low-temperature nuclear orientation method.抄録全体を表示PDF形式でダウンロード (106K) -
Katsuhiko Fujii, Yutaka Aikawa, Yojiro Shimazutsu2003 年 72 巻 3 号 p. 727-729
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありAn instability of the order–disorder ferroelectrics is studied in the variationl method at finite temperature. A double-well potential based on the unfied oscillator model is adopted as a trial potential and a crystal potential is given by superposing the back-to-back Morse potentials. It is shown that occurrence of the instability is attributed to changes in shape of the crystal potential. The transition temperature and the soft mode frequency are shown in terms of the microscopic quantities dependent on substances.抄録全体を表示PDF形式でダウンロード (75K) -
Mamoru Kitaura, Minoru Itoh, Hideyuki Nakagawa, Masami Fujita2003 年 72 巻 3 号 p. 730-734
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありThe excitation spectra for two intrinsic luminescence bands at 3.76 eV (UV) and 2.62 eV (BG) in PbCl2 have been measured using synchrotron radiation in the energy range up to 25 eV at 10 K. Since the UV and BG bands are connected to excitonic luminescence and electron–hole (e–h) recombination luminescence, respectively, an analysis of the difference in their excitation spectra allows us to separate excitonic and e–h mechanisms in the multiplication of electronic excitations. It is found that the intensity of the UV emission is sharply increased at 9.8 eV, which is higher than twice the band gap energy. Secondary excitons are formed by inelastic scattering of hot photoelectrons in the region above 9.8 eV. On the other hand, the BG emission is gradually enhanced in the range of 9–12.5 eV, and the intensity doubles at around 12.5 eV. This result indicates that the creation of two e–h pairs per photon predominantly causes in the region above 12.5 eV. The e–h multiplication originates not only in inelastic scattering of hot photoelectrons in the 12.5–25 eV range but also in interband Auger recombination of holes in the Cl− core levels with valence electrons in the 18–25 eV range.抄録全体を表示PDF形式でダウンロード (129K) -
Yasuhiko Isohata, Masaki Hayashi2003 年 72 巻 3 号 p. 735-742
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありOn the basis of the power spectrum analyses for the base (nucleotide) sequences of various genes, we have studied long-range correlations in total base sequences which are expressed as 1⁄fα, behaviour of the exponent α for the accumulated base sequences as well as periodicities at short range. In particular from the analysis of content rate distributions of α we have obtained the average value \\barα=0.40±0.01 and \\barα=0.20±0.01 for the human genes and S. cerevisiae genes, respectively. We have also performed the analyses using the mutual information function. We show that there exists a clear difference between the content rate distributions of correlation lengths for the sample human genes and the S. cerevisiae genes. We are led to a conjecture that the elongation of the correlation length in the base sequences of genes from the early eukaryote (S. cerevisiae) to the late eukaryote (human) should be the definite reflection of the evolutionary process.抄録全体を表示PDF形式でダウンロード (202K) -
Fukuo Yoshida, Kihachiro Horiike, ShiPing Huang2003 年 72 巻 3 号 p. 743-750
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありAn analytic formula is established for the concentration profile of secreted molecules by solving the diffusion equation in the case of a time-dependent secretion rate with non-uniformity in its magnitude and direction. It is explicitly shown that the concentration exhibits a significant angular dependence in a region near the secreting cell. The formula is applied to estimate the non-uniform secretion effect on an effective communication distance for human cytokines in intercellular signaling.抄録全体を表示PDF形式でダウンロード (142K) -
Hiroyuki Koga, Masahiro Nakagawa2003 年 72 巻 3 号 p. 751-761
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありIn the present work, we propose a chaotic vocal synthesis model of vowels, which can achieve the synthesis of the chaotic fluctuation observed in real vocal sounds. The chaotic fluctuation can be generated by the proposed exponential oscillation functions in the glottis model. The nonlinearity of the cord oscillation can be controlled by three parameters. We examine the existence of chaos in the attractors reconstructed from the synthesized vocal sound waveforms by evaluating the Lyapunov exponents. We also apply the surrogation test to examine the nonlinear dynamics behind the vocal organs. Our results show that the proposed vocal synthesis model possesses an ability to generate the appropriate chaotic fluctuation observed in the human vocal sounds.抄録全体を表示PDF形式でダウンロード (326K) -
Kimiaki Konno, Hiroshi Kakuhata2003 年 72 巻 3 号 p. 762
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありPDF形式でダウンロード (43K) -
Yi Zhang, Shu-fang Deng, Deng-yuan Chen2003 年 72 巻 3 号 p. 763-764
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありPDF形式でダウンロード (67K) -
Yutaka Moritomo, Yasuo Ohishi, Akira Kuriki, Eiji Nishibori, Masaki Ta ...2003 年 72 巻 3 号 p. 765-766
発行日: 2003/03/15
公開日: 2007/07/25
ジャーナル 認証ありPDF形式でダウンロード (122K)