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Volume 72, Issue 1
Displaying 1-38 of 38 articles from this issue
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Katsuhiro Nakamura, Jun Ma2003 Volume 72 Issue 1 Pages 1-4
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe bridge between nonlinear dynamics and quantum transport in three-dimensional (3D) quantum dots, by investigating the semiclassical conductance for open 3D ballistic billiards. For partially or completely broken-ergodic 3D billiards such as SO(2) symmetric billiards, the dependence of the conductance on the Fermi wave number is dramatically changed by the lead orientation. In the case of the vertical lead orientation, application of the symmetry-breaking weak magnetic field to such billiards brings about the Arnold diffusion that cannot be seen in 2D billiards. In contrast to the 2D case, the enhanced negative magnetoresistance near the zero field occurs due to the classical Arnold diffusion in addition to a possible quantal weak localization correction.View full abstractDownload PDF (118K) -
LingTi Kong, HaoRan Gong, WenSheng Lai, BaiXin Liu2003 Volume 72 Issue 1 Pages 5-8
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe proposed a method of constructing a realistic n-body potential based on the embedded atom method (EAM) for the equilibrium immiscible Cu–Ta system, in which no equilibrium compound exists. The Cu–Ta cross potential was derived by fitting some physical properties of the nonequilibrium B2 CuTa and L12 Cu3Ta phases determined by ab initio calculations. The constructed potential was then applied to study the interfacial behavior between Cu and Ta through molecular dynamics simulations performed at 300 and 800 K, respectively. Two fcc-Cu/bcc-Ta bilayer models were employed and one model included a preset disordered interlayer. It was found that a few Ta atoms could move into the Cu lattice at the imperfect Cu/Ta interface at high temperature.View full abstractDownload PDF (147K) -
XinYu Li, ZhengCao Li, BaiXin Liu2003 Volume 72 Issue 1 Pages 9-12
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSUnique structural evolution was observed in the suitably designed nanosized Pd–Ru multilayers by a scheme named ion beam manipulation, i.e., ion beam mixing in a controllable manner. With increasing the ion dose, the original polycrystalline Pd and Ru first transformed into an intermediate state of single crystalline fcc phase, which later turned into a well-grown ordered structure. When the multilayers were over-irradiated, the ordered structure showed an apparent tendency of returning to a polycrystalline state of fcc Pd-enriched solid solution. We report, in this Letter, experimental observations as well as a brief discussion concerning the roles of interfacial free energy and irradiation dose in manipulating the structural evolution observed in the Pd–Ru multilayers.View full abstractDownload PDF (164K) -
Yoshimichi Nakamura, Hiroaki Koga, Satoshi Watanabe2003 Volume 72 Issue 1 Pages 13-16
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report a remarkable series of structural changes newly predicted for a Si(111)\\sqrt3×\\sqrt3-Ag surface with defects. Monte Carlo simulations based on the results of first-principles calculations show that in a particular configuration of a few defects, a wide region undergoes disorder → order → disorder → order structural changes with the decrease of temperature. We call this series of changes multistage order–disorder surface (MODS) transition, which is able to be observed by scanning tunneling microscopy (STM) as a series of clear changes of the image.View full abstractDownload PDF (3956K) -
K. Chatani, Y. Endoh2003 Volume 72 Issue 1 Pages 17-20
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report experimental results from systematic studies on the interplay between the antiferromagnetic spin density wave and the superconductivity in Cr1−xRux alloys. Unlike previous reports, the two phases never coexist and the phase transition as the function of x appears to be of the first order. This clean evidence leads to a conclusion that the antiferromagnetic SDW is stabilized by the excitonic phase formation competing with the Bose condensation of the superconductivity in Cr1−xRux alloys.View full abstractDownload PDF (246K) -
Zenji Hiroi, Masafumi Hanawa, Yuji Muraoka, Hisatomo Harima2003 Volume 72 Issue 1 Pages 21-24
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSElectronic properties of the metallic pyrochlore oxide Cd2Re2O7 are studied by means of electrical resistivity and Hall measurements. Semimetallic band structures are revealed as expected from band structure calculations. It is found that large changes in carrier density and mass occur at the structural phase transition at Ts1=200 K. A large mass enhancement is observed, particularly for the high-temperature phase with the ideal pyrochlore structure, suggesting that an anomalous correlation has an important effect on the itinerant electrons in the pyrochlore lattice.View full abstractDownload PDF (115K) -
Shinichiro Kobayashi, Yasuhiro Yoshino, Shigenari Tsuji, Masafumi Sera ...2003 Volume 72 Issue 1 Pages 25-28
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have studied the coexistence and the competition between the Kondo singlet state and the long-range antiferro(AF)magnetic ordering in the CexNd1−xB6 system. At high temperatures, the single impurity Kondo effect is observed in all the samples as in the CexLa1−xB6 system. In the AF magnetic state formed mainly by Nd ions, Ce ions contribute to the AF magnetic ordering but at the same time exhibit the Kondo singlet character with a small effect from the magnetic ordering. The ground state of CexNd1−xB6 changes with x; in a small x region, the Kondo singlet state is destroyed by the exchange field from surrounding Nd moments. Above x∼0.3, the long-range magnetic order takes place because the Ce–Ce interaction overcomes the Kondo effect. In an intermediate x value between the above two regions, the Kondo singlet state may continue to exist down to a very low temperature.View full abstractDownload PDF (119K) -
Kazuki Ohishi, Takahiro Muranaka, Jun Akimitsu, Akihiro Koda, Wataru H ...2003 Volume 72 Issue 1 Pages 29-32
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe magnetic penetration depth λ in the mixed state of MgB2 has been determined microscopically from the field distribution around magnetic vortices probed by muon spin rotation. Both the temperature and magnetic field dependence of λ strongly suggest the presence of delocalized quasiparticles around the vortex cores. In particular, the effect of Doppler shift has been clearly observed as a finite gradient of the field dependence of λ, strongly suggesting an anisotropic order parameter with the region of a vanishingly small energy gap.View full abstractDownload PDF (118K) -
Takateru Kawakami, Saburo Nasu, Kaori Kuzushita, Tetsuya Sasaki, Shota ...2003 Volume 72 Issue 1 Pages 33-36
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe perovskite oxide SrFeO3 has been investigated by high-pressure 57Fe Mössbauer spectroscopy and X-ray powder diffraction (XRD) up to 62 GPa and 56 GPa, respectively. Magnetic ordering occurs below 134 K at 0.1 MPa and below 210 K at 15 GPa. Above 17 GPa, the magnetic ordering temperature increases markedly to above 400 K. The cubic crystal structure of SrFeO3 has been confirmed to persist up to 56 GPa by using XRD with synchrotron radiation.View full abstractDownload PDF (146K) -
Masaki Takesada, Toshirou Yagi, Mitsuru Itoh, Shin-ya Koshihara2003 Volume 72 Issue 1 Pages 37-40
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSA gigantic enhancement of dielectric constant by UV light irradiation is reported for the first time in the quantum paraelectric family of perovskite oxides, such as SrTiO3 and KTaO3, under a weak DC field. The enhancement has not been observed in ferroelectric SrTi18O3 induced by substitution of 18O for 16O. The present result suggests a new class of light-switching phenomena controllable externally.View full abstractDownload PDF (98K) -
Tomoharu Hasegawa, Shin-ichiro Mouri, Yasuhiro Yamada, Koichiro Tanaka2003 Volume 72 Issue 1 Pages 41-44
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDielectric properties are studied in quantum paraelectric SrTiO3 under UV-light illumination from 100 Hz to 1 MHz at low temperatures. We demonstrate that the complex dielectric constant is strongly enhanced by interband photo-excitation. Dispersion measurements confirm that the photo-induced Debye-type relaxator enhances the dielectric constant. The anomalous temperature and excitation–density dependence of the relaxation time suggests that photo-induced polar domains with finite lifetime lead to the novel dielectric properties.View full abstractDownload PDF (198K) -
Yutaka Maniwa, Hiromichi Kataura, Masatoshi Abe, Akihiko Fujiwara, Ryu ...2003 Volume 72 Issue 1 Pages 45-48
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report the structural study of C70-one-dimensional (1D) crystal formed inside single-walled carbon nanotubes (SWNTs). X-ray diffraction measurements were performed between 100 K and 999 K on C70-encapsulated SWNTs with an average diameter of 1.37 nm. Two different domains, where the dominant alignment of C70 molecular long axis is standing or lying with respect to the tube axis, were observed; the ratio of the standing to the lying C70-domains is roughly 7:3. Thermal expansion of interfullerene distance gave no evidence for orientational phase transitions, not as in the 3D crystals. Instead, the long-range order of the standing C70-alignment was thermally destroyed with an activation energy of 39±4 meV. The results imply the importance of either the 1D fluctuation or the tube-C70 interaction at finite temperatures.View full abstractDownload PDF (180K) -
Qing Ding, Zuonong Zhu2003 Volume 72 Issue 1 Pages 49-53
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSBy introducing the conception of given curvature formulation for partial differential equations, we show that the Landau–Lifshitz equation (LLE) is gauge equivalent to a nonlinear Schrödinger-like equation, which answers a question proposed by Bordag and Yanovski. As a direct consequence, explicit first-order approximate 1-soliton solutions (with respect to the interaction anisotropy) to the LLE are constructed from those to the nonlinear Schrödinger-like equation.View full abstractDownload PDF (92K) -
Shun-ichi Yoshida, Norihiro Ihara, Koh Wada2003 Volume 72 Issue 1 Pages 54-61
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe path probability method (PPM) in the tetrahedron-cactus approximation is applied to the Slater-Takagi model with dipole–dipole interaction for KH2PO4-type hydrogen-bonded ferroelectric crystals in order to derive a small dip structure in the real part of dynamical susceptibility observed at the transition temperature Tc. The dip structure can be ascribed to finite relaxation times of electric dipole moments responsible for the first order transition in contrast with the critical slowing down in the second order transition. The light scattering intensity which is related to the imaginary part of dynamical susceptibility is also calculated above and below the transition temperature and the obtained central peak structure is consistent with polarization fluctuation modes in Raman scatterin experiments.View full abstractDownload PDF (182K) -
Yuichi Togashi, Kunihiko Kaneko2003 Volume 72 Issue 1 Pages 62-68
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe study an autocatalytic system consisting of several interacting chemical species. We observe a strong dependence of the concentrations of the chemicals on the size of the system. This dependence is caused by the discrete nature of the molecular concentrations. Two basic mechanisms responsible for them are identified and elucidated. The relevance of the transitions to processes in biochemical systems and in micro-reactors is briefly discussed.View full abstractDownload PDF (376K) -
Hidetsugu Sakaguchi2003 Volume 72 Issue 1 Pages 69-73
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe study numerically stick slip motions in a model of blocks and springs being pulled slowly. The sliding friction is assumed to change dynamically with a state variable. The transition from steady sliding to stick-slip is subcritical in a single block and spring system. However, we find that the transition is continuous in a long chain of blocks and springs. The size distribution of stick-slip motions exhibits a power law at the critical point.View full abstractDownload PDF (180K) -
Mitsuhiro Itakura2003 Volume 72 Issue 1 Pages 74-82
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWith the help of the improved Monte Carlo renormalization-group scheme, we numerically investigate the renormalization group flow of the antiferromagnetic Heisenberg and XY spin model on the stacked triangular lattice (STA-model) and its effective Hamiltonian, 2N-component chiral φ4 model which is used in the field-theoretical studies. We find that the XY-STA model with lattice size 126×144×126 exhibits clear first-order behavior. We also find that the renormalization-group flow of the STA model is well reproduced by the chiral φ4 model, and that there are no chiral fixed points of renormalization-group flow for N=2 and 3 cases. This result indicates that the Heisenberg-STA model also undergoes first-order transition.View full abstractDownload PDF (290K) -
Kazuto Oshima2003 Volume 72 Issue 1 Pages 83-88
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSSpontaneous symmetry breaking in (1+1)-dimensional φ4 theory is studied with discretized light-front quantization. To compute the critical coupling we calculate the vacuum expectation value of a zero mode through the commutation relations [a0,an] in the Tamm–Dancoff-like approximation. We also estimate effects of non-diagonal interactions to the critical coupling. Our result of the critical coupling is λcr=28.0μ2⁄h, which is consistent with the equal-time result 22μ2⁄h≤λcr≤55.5μ2⁄h.View full abstractDownload PDF (106K) -
A. M. El Misery, Abd El Hakeem, Abd El Naby, Abd Hameed El Nagar2003 Volume 72 Issue 1 Pages 89-93
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe problem of peristaltic transport of a fluid with variable viscosity through the gap between concentric uniform tubes, such that the inner tube is rigid and outer tube with sinusoidal wave travelling down its wall, has been investigated under zero Reynolds number, and long wavelength approximations. The velocity field in the gap, relations between the pressure gradient and flow rate and that between the friction forces on the inner and outer tubes and the flow rate are obtained in terms of viscosity parameter, radius ratio and the degree of occlusion. The peristaltic pumping and augmented pumping are discussed with the physical parameters of interest.View full abstractDownload PDF (111K) -
K. Uehara, M. Maeda, A. Tsushima, H. Amemiya2003 Volume 72 Issue 1 Pages 94-100
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSUsing particle and energy conservation laws, particle and thermal diffusivities for both ions and electrons perpendicular to the flux surface at the scrape-off layer (SOL) in tokamaks were evaluated just outside the magnetic separatrix, where the source term due to ionization, charge exchange loss and the effect of the temperature gradient is exactly included. The diffusivities are expressed in terms of e-folding length of the density, temperatures and Mach number and its absolute values were evaluated using the data obtained by the electrostatic probe in SOL plasma in JFT-2M tokamak.View full abstractDownload PDF (148K) -
Fujio Kakinuma, Masaki Sakurai, Yoshimi Tsuchiya, Toshiharu Fukunaga, ...2003 Volume 72 Issue 1 Pages 101-106
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe measurements of sound velocity and neutron scattering in the liquid state, and DSC and XAFS measurements in the amorphous state were carried out for Ge15Te85 and Ge15Te85−XMX (M = Ag, Cu and In) to investigate the correlation between the glass forming ability and local structure in the liquid and amorphous states. The results suggest that there exists Cu2Te like chemical short-range order in liquid and amorphous Ge15Te80Cu5. Similar results are obtained for liquid and amorphous Ge15Te80Ag5 alloys. The local structure around In atoms is different from those of Ag and Cu atoms, which could be attributed to the difference in the chemical bonds between M and Te. In the Ge15Te85−XMX (M = Ag, Cu and In) alloys, the structure of glasses and the glass forming ability would be closely related to the liquid structure and nature of the Te–M bonds.View full abstractDownload PDF (135K) -
Timbangen Sembiringa, Dilip Kumar Saha, Miwako Takahashi, Toetsu Shish ...2003 Volume 72 Issue 1 Pages 107-110
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSAtomic diffuse scattering intensity from a single crystal of fcc Pt–12.5 at.% Mn alloy was measured with the use of X-ray diffraction. Diffuse intensity maxima at 1/2 1/2 1/2 and its equivalent positions were observed in addition to diffuse intensity maxima at 100 and its equivalent positions on the diffraction patterns. The Warren–Cowley atomic short-range order parameters, αlmn, were determined. At least, first 21 αlmn parameters were needed to reproduce both kinds of diffuse maxima. The correlation length was about 14 A, indicating that the local fluctuation due to the ABC6 type ordered structure still exists in the disordered state of Pt–12.5 at.% Mn alloy.View full abstractDownload PDF (138K) -
Kwangho Park, In-mook Kim2003 Volume 72 Issue 1 Pages 111-116
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe studied the quenched Edwards–Wilkinson (QEW) equation with power-law type of a correlated noise near the depinning threshold. We solved analytically the QEW equation by using a functional renormalization group method. We obtained the critical exponents characterizing the depinning transition. We found that the value of the roughness exponent increases from 1 to 1.46341 in one spatial dimension as ρ does from 0 to 0.5, where ρ is a constant characterizing the degree of the correlation.View full abstractDownload PDF (109K) -
B. C. Anusionwu, F. O. Ogundare, C. E. Orji2003 Volume 72 Issue 1 Pages 117-121
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe possible compounds existing in the liquid Cu–Hf alloy at 1650 and 1873 K have been verified using a statistical mechanical model based on complex formation in compound forming liquid alloys. CuHf2 is the more stable compound at high temperatures though its existence appear more predominant at lower concentrations of Hf. Other compounds, Cu4Hf and Cu5Hf also exist throughout the concentration range but its influence on the thermodynamic properties of the liquid Cu–Hf alloy is low.View full abstractDownload PDF (98K) -
Tatsuma D. Matsuda, Naoto Metoki, Yoshinori Haga, Shugo Ikeda, Tomoyuk ...2003 Volume 72 Issue 1 Pages 122-130
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe have grown a single crystal of UCr2Si2 for the first time. UCr2Si2 exhibits a structural transition from the ThCr2Si2-type (I4⁄mmm) to the triclinic structure (P\\bar1) below Ta=210 K. The antiferromagnetic structure was determined by means of neutron diffractions, indicating the propagation vector Q=[−\\frac12,\\frac12,0] and the magnetic moment 0.65μB/U oriented along the [0,0,1] direction. The high-field magnetization at 4.2 K indicates a metamagnetic transition at 11.4 T, reaching 0.65μB/U at 14.9 T. The medium size of the electronic specific heat coefficient γ=80 mJ/K2mol, the magnetic entropy about half of Rln2 at TN and a small effective moment 2.45μB/U indicate that the antiferromagnetic state is due to 5f-electrons with an itinerant character.View full abstractDownload PDF (954K) -
Alexander I. Khachaturov, Eiji Hatta, Vladimir M. Svistunov2003 Volume 72 Issue 1 Pages 131-134
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSElectron tunneling between a Fermi metal and a narrow band conductor with non-quadratic E–k relationship is treated. It is shown that the tunneling characteristics of such junctions are very sensitive to barrier parameters. This sensitivity is supposed to be a main reason for disagreements among experimental data.View full abstractDownload PDF (90K) -
Katsuki Amemiya2003 Volume 72 Issue 1 Pages 135-142
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe interference phenomenon of tunneling electrons in a magnetic field is studied by calculating the conductance in a structure which is similar to an Aharonov–Bohm (AB) ring, that is, a rectangle-shaped finite potential barrier in a straight quantum wire. The overall interference pattern resembles the AB oscillation fairly well. However, the aperiodicity of the pattern is in sharp contrast with the conventional AB oscillation. The behavior of the oscillation is very similar even when the lateral width of the potential barrier is the same as that of the quantum wire. In addition, the suppression of tunneling by the magnetic field is found to depend on the width of quantum wires. At high magnetic fields, the narrower the wire is, the larger the tunneling probability can be.View full abstractDownload PDF (423K) -
Yugo Oshima, Hitoshi Ohta, Keiichi Koyama, Mituhiro Motokawa, Hiroshi ...2003 Volume 72 Issue 1 Pages 143-148
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSMagnetooptical measurements of several quasi-two-dimensional (q2D) organic conductors, which have simple Fermi surface structure, have been performed by using a cavity perturbation technique. Despite of the simple Fermi surface structure, magnetooptical resonance results show a dramatic difference for each sample. Cyclotron resonances (CR) were observed for θ-(BEDT-TTF)2I3 and (BEDT-TTF)3Br(pBIB), while periodic orbit resonances (POR) were observed for (BEDT-TTF)2Br(DIA) and (BEDT-TTF)3Cl(DFBIB). The selection of the resonance seems to correspond with the skin depth for each sample. The effective mass of POR seems to have a mass enhancement due to the many-body effect, while effective mass of CR is independent of the strength of the electron–electron interaction. The scattering time deduced from each resonance’s linewidth will be also presented.View full abstractDownload PDF (145K) -
Takehiko Mori, Mao Katsuhara2003 Volume 72 Issue 1 Pages 149-154
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSMagnetic interactions in molecular magnets of charge-transfer complexes which consist of organic donors and metal-complex anions such as (TTF)[Cr(NCS)4(phen)], (BEDT-TTF)[Cr(NCS)4(isoq)2], and (TMTTF)[Cr(NCS)4(phen)]CH2Cl2, are estimated from intermolecular overlap integrals obtained by the extended Hückel calculation. The NCS parts rather than the π-ligands of the anions show large overlap with the π-donor molecules; this is the main origin of the strong πd-interactions. The calculation affords the estimation of the J networks, from which the anisotropy is discussed.View full abstractDownload PDF (449K) -
Takeo Jo2003 Volume 72 Issue 1 Pages 155-159
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe effect of the 3d spin–orbit interaction (SOI) on the magnitude of orbital magnetic moment (ML) of the trivalent vanadium ion with two t2g electrons in perovskite-type antiferromagnetic vanadates is discussed on the basis of a tight-binding model taking into account the 3d–3d multipole interaction. The second order perturbational calculation with respect to the electron transfer between V ions shows that SOI induces, for the so-called G-type antiferromagnetism (AF) accompanied by the so-called C-type orbital ordering, ML which tends to −1μB [antiparallel to the spin moment (MS) of 2μB corresponding to spin S=1], in the vanishing C-type Jahn–Teller distortion. For the C-type AF accompanied by the G-type orbital ordering, on the other hand, the induced ML is shown to reduce the perturbational energy gain especially in the c-direction. On the basis of these, we propose the magnitude of several tenths μB for V ion and discuss its 3d orbital state in vanadates including LaVO3 and YVO3 by bearing in mind the Jahn–Teller distortion.View full abstractDownload PDF (101K) -
Tomo Munehisa, Yasuko Munehisa2003 Volume 72 Issue 1 Pages 160-169
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe investigate excited states of the Shastry–Sutherland model using a kind of variational method. Starting from various trial states which include one or two triplet dimers, we numerically pursue the best evaluation of the energy for each set of quantum numbers. We present the energy difference as a function of either the coupling ratio or the momentum and compare them with the perturbative calculations. Our data suggest that the helical order phase exists between the singlet dimer phase and the magnetically ordered phase. In comparison with the experimental data we can estimate the intra-dimer coupling J and the inter-dimer coupling J′ for SrCu2(BO3)2: J′⁄J=0.65 and J=87 K.View full abstractDownload PDF (151K) -
C. W. Chiu, F. L. Shyu, C. P. Chang, R. B. Chen, M. F. Lin2003 Volume 72 Issue 1 Pages 170-177
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSThe absorption spectra of the AB- and AA-stacked nanographite ribbons have several prominent peaks. They strongly depend on the edge structure, the ribbon width, the stacking sequence, and the polarization direction. The armchair ribbons quite differ from the zigzag ribbons. The frequency and the number of the absorption peaks are affected by the ribbon width. The AB-stacked systems have lower threshold absorption frequency, more absorption peaks, and weaker spectral intensity, as compared with the AA-stacked systems. The absorption spectra are highly anisotropic. The optical excitations of the parallel polarization (E||||\\hatz) are absent in the AA-stacked systems. Comparison with graphite is discussed.View full abstractDownload PDF (207K) -
Mariko Higuchi, Jun Matsui, Takashi Odagaki2003 Volume 72 Issue 1 Pages 178-184
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSWe report results of molecular dynamics simulation for the supercooled state of a model diatomic molecular liquid possessing a rotational degree of freedom. We develop a new technique to extract the contribution of the internal motion in the intermediate scattering function and in the imaginary part of the generalized susceptibility, and show that the rotational relaxation becomes well separated from the center-of-mass relaxation as temperature is reduced. We identify three processes in the susceptibility. The relaxation time of the α relaxation produced mainly by the slow relaxation of the center-of-mass motion can be fitted well with the Vogel–Fulcher low. A secondary peak is observed at the high frequency side of the α-peak, and is shown to be produced by the internal degree of freedom. The features of the secondary relaxation process are consistent with the Johari–Goldstein process. The relaxation process of an elongate model and a rigid model molecular liquid are also studied and we show that the Johari–Goldstein process cannot be identified in the elongate model system.View full abstractDownload PDF (173K) -
Masakatsu Misawa2003 Volume 72 Issue 1 Pages 185-188
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSCluster-formation in 1-propanol aqueous solution has been examined by a reverse Monte Carlo analysis of neutron small angle scattering intensity measured on the solution with an alcohol content of 0.167 in mole fraction. Cluster-size distribution, structure of cluster and composition of cluster have been analyzed. The cluster-size distribution ranges from very small value, as small as one propanol molecule, to larger one continuously. By the addition of salt the mean size of cluster increases, while the size-distribution itself is scaled very well between the salt-free solution and salt-added solution, showing clearly a self-similarity of the mesoscale structure of both solutions. The ratio of the number of water molecules to 1-propanol molecules in each cluster tends to be about 2 at larger clusters regardless of salt content, giving some insight into a microscopic origin of cluster-formation of the current solution.View full abstractDownload PDF (143K) -
Xing-Biao Hu, Bo-Ling Guo, Hon-Wah Tam2003 Volume 72 Issue 1 Pages 189-190
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (61K) -
Jong-Ho Park, Chung-Sik Kim, Byung-Chun Choi, Hyo-Jin Seo2003 Volume 72 Issue 1 Pages 191-192
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (78K) -
Akihiko Machida, Yutaka Moritomo, Kenji Ohoyama, Arao Nakamura2003 Volume 72 Issue 1 Pages 193-194
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (82K) -
B. Lüthi, S. Zherlitsyn, C. Geibel2003 Volume 72 Issue 1 Pages 195
Published: January 15, 2003
Released on J-STAGE: July 25, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (51K)
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