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Yukiyasu Ozeki, Nobuyasu Ito, Keita Ogawa
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3471-3474
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Numerical evidence that the number of pure states in the spin glass phase is infinite near the ferromagnetic phase boundary for the three dimensional (3D) ± J Ising model and 3D gauge glass models is presented. It is consistent with the mean field theory which suggests the multivalley structure of the spin glass phase. We will show that the onset of the ferromagnetic long-range order and that of the ferromagnetic spontaneous symmetry breaking do not coincide with each other, and this phenomenon characterizes the structure of the phase space.
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Jun Akimitsu, Hirohiko Ichikawa, Naotoshi Eguchi, Tomoko Miyano, Masak ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3475-3478
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The orbital ordering in the ferromagnetic YTiO
3 (T
C ∼= 30 K) has been observed by means of the polarized neutron diffraction technique. The observed magnetic form factors obtained from the aspherical contribution of the spin density distribution have been satisfactorily explained by the linear combination of the wave functions |zy› and |zx› in terms of the orbital ordering scheme.
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Akira Onuki
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3479-3482
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Jahn-Teller structural phase transitions are examined using a simple Ginzburg-Landau approach. The order parameter representing orbital order is complex for the case of doubly degenerate d-orbital states. We find tricritical behavior in ferromagnet-like orbital order under applied uniaxial stress and in antiferromagnet-like orbital order with varying the strength of the interaction between the two sublattices.
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Takayuki Ichikawa, Mikio Yamamoto, Seiji Higashitani, Katsuhiko Nagai
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3483-3486
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Sound propagation in a Fermi liquid with impurities is studied using the Landau-Boltzmann equation and the result is compared with that of a recent experiment in liquid
3He in aerogel by the Northwestern University group. The sound absorption calculated using a fixed impurity model is a few orders of magnitude larger than the experimental value. We take into account the simultaneous motion of aerogel molecules and propose a model in which the momentum loss of
3He quasi-particles during collisions with the aerogel is converted to a drag force that acts on the aerogel molecules. This collision drag model provides a reasonable description for the temperature and the pressure dependence of the observed sound velocity and absorption.
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Kentaro Nomura, Daijiro Yoshioka
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3487-3490
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Transitions from a paired quantum Hall state to another quantum Hall state in bilayer systems are discussed in the framework of the edge theory. Starting from the edge theory for the Haldane-Rezayi state, it is shown that the charging effect of a bilayer system which breaks the SU(2) symmetry of the pseudospin shifts the central charge and the conformal dimensions of the fermionic fields which describe the pseudospin sector in the edge theory. This corresponds to the transition from the Haldane-Rezayi state to Halperin's 331 state, or from a singlet d-wave to a triplet p-wave ABM type paired state in the composite fermion picture. Considering interlayer tunneling, the tunneling rate-capacitance phase diagram for the ν=5/2 paired bilayer system is discussed.
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Wilson Agerico Diño, Katsuyuki Fukutani, Tatsuo Okano, Hideaki ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3491-3494
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We compare the scattering dynamics of H
2/Cu
3Pt(111)[121] and H
2/NiAl(110)[110], with the corresponding results for H
2/Cu(001)[100] and H
2/Ni(110)[001]. We show that H
2 can indeed distinguish between surfaces and between surface components, and these discernible (by H
2) differences manifest as measurable/observable transitions in the internal states of the scattered H
2. Based on these results, we discuss how, after a systematic and comprehensive study, it would be feasible to study adsorbate-surface interaction (local surface reactivity), and surface structures, as well as to determine the corresponding effective potential energy (hyper-) surface using H
2(D
2) probes.
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Masahiko Hayashi, Hiromichi Ebisawa
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3495-3498
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Little-Parks oscillation of a Möbius strip (or ring, equivalently) made of a superconductor is studied based on Ginzburg-Landau theory. It is shown that, if the strip is sufficiently wide, a novel state appears when the number of magnetic flux quanta threading the ring is close to a half odd integer. As a result, the shape of Little-Parks oscillation of critical temperature is modified. We estimate the free energy of this state and give the phase diagram of the superconducting Möbius strip in a magnetic field.
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Shigeru Koikegami, Takashi Yanagisawa
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3499-3502
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The superconductivity of the two-dimensional d-p model up to the second order of the Coulomb repulsion U
d is investigated in the weak-coupling formalism. Near the half-filling, the superconducting gap function has b
1g symmetry. The dependences of the gap magnitude on both the total hole density and the ratio of the number of d-holes to the number of p-holes are also studied. These dependences make it clear that the presence of the Van Hove singularity can make gap magnitudes large even in the case of small U
d.
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Takahiro Sawa, Masahiro Matsumura, Hideki Yamagata
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3503-3506
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The Cu-NQR spectra were measured in a wide temperature range from 300 K to 1.5 K to investigate the ordering process and the structure of the static spin-charge stripe order in La
2-x-yEu
ySr
xCuO
4 with x=1/8. The usual NQR spectrum observed above the structural transition temperature, T
d2=138 K, from LTO to LTT shows the decrease of the signal intensity below T
d2 due to the rapid increase of the spin echo decay without change of the lineshape, and the signal wiped out completely below 40 K. We assigned the temperature T
charge∼=85 K, at which the spin echo decay rate increases abruptly, as a representative one for the slowing down toward static charge stripe ordering. Below T
spin ∼= 8 K, the signal starts to reappear as an abnormally broad spectrum with a tail extending to 70 MHz or more, which is evidence of the static spin and/or charge order. The spectrum is simulated satisfactorily in terms of the stripe order with the modulation amplitude for the Cu moment of about 0.22 μ
B.
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Kuen Lee, P. M. Hui, Bing-Hong Wang, Neil F. Johnson
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3507-3510
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
A two-route traffic model with a built-in decision-making process is proposed and studied numerically. The instantaneous average speeds on the routes are announced as global information. Two types of drivers, dynamic and static, are introduced. The dynamic drivers use the global information for making decisions. It is shown that announcing the instantaneous average speeds on the routes results in a better performance of the two-route system in terms of the traffic flux compared to announcing the transit time. When the static drivers randomly select a route, the presence of the dynamic drivers does not improve the traffic flux of the system. When the static drivers tend to select a particular route, the presence of dynamic drivers leads to a higher flux. Our model thus incorporates the effects of adaptability into the cellular automaton models of traffic flow.
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Juan García Escudero, Javier García Garcia
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3511-3516
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Several species of tilings with eight-fold symmetry generated by means of inflation rules are studied. They can also be obtained by superposition of other patterns. The complexity of the structures is reflected in the sets of vertex configurations. Composition of the basic inflation rules gives face to face tilings. The diffraction patterns of the simple tilings show Bragg peaks.
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Satoru Saito, Noriko Saitoh, Jun-ichi Yamamoto, Katsuhiko Yoshida
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3517-3523
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We propose a method to characterize discrete time evolution equations, which generalize discrete time soliton equations, including the q-difference Painlevé IV equations discussed recently [K. Kajiwara
et al.: nlin. SI/0012063; T. Masuda: nlin. SI/0107050].
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Hiroaki Ono
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3524-3528
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
By making use of a naïve model of nonlinear dielectric medium, the propagation of electromagnetic waves with long wave length is investigated. By the reductive perturbation method, the equation governing it has been derived, which takes the form of a vector type of modified KdV equation. Based upon this equation, we have considered the behaviors of nonlinear waves. It is found that this equation has a vector type of dark solitary wave solution in addition to a scalar type of bright or dark solitary wave solutions. The weak modulation of the wave train solution is described by the coupled nonlinear Schrödinger equation and shows the nonlinear rotation of the principal axes of the elliptically polarized wave.
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Hirofumi Morise, Miki Wadati
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3529-3534
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We study dynamics of a wavefunction for the nonlinear Schrödinger equation with attractive self-interaction under a harmonic potential. By use of the variance identity and a rigorous inequality, we obtain a sufficient condition for the collapse of the wavefunction. By applying this method, we investigate the dynamic stability of a trapped Bose-Einstein condensate and its dependence on the initial shape of the condensate. The result agrees qualitatively well with the results of the time-dependent variational method. We find that the anisotropy introduced in the initial state has a significant effect on the stabilization.
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Masahiro Shiroishi, Minoru Takahashi, Yoshihiro Nishiyama
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3535-3543
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We study a correlation function for the one-dimensional isotropic XY model (XX0 model), which is called the Emptiness Formation Probability (EFP). It is the probability of the formation of a ferromagnetic string in the anti-ferromagnetic ground state. Using the expression of the EFP as a Toeplitz determinant, we discuss its asymptotic behaviors. We also compare the analytical results with numerical calculations as the density-matrix renormalization group and the quantum Monte-Carlo method.
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Shigeo Hayashi, Shunsuke Uchiyama, Naser Harba
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3544-3549
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
As a possible cause of residual background in Mie scattering by a sonoluminescing single bubble, double scattering involving the bubble and surrounding small particles is examined. For reasonable values of the density and size of the particles, which are assumed to be distributed randomly and uniformly, the double scattering is estimated to contribute considearably to the ordinary Mie scattering. The theory suggests how the double-scattering contribution can be reduced.
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Shinichiro Yanase, Genta Kawahara, Hiroshi Kiyama
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3550-3555
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The three-dimensional vortical structures created in the downstream of the moderate-Reynolds-number (
Re ≤ 700) backward-facing step flow are studied based on the direct numerical simulation (DNS). The flow is assumed to be periodic in the spanwise direction. The vortical structure manifests itself in the form of zig-zag arrangement of alternating quasi-streamwise structures with positive and negative streamwise vorticity, which has been observed in the buffer region of the turbulent channel flow by DNS [J. Fluid Mech.
332 (1997) 185]. In order to excite the perturbation, we triggered the flow by giving discontinuity of the time derivative of the inlet flow initially. It is found that the condition whether the three-dimensional vortical structures appear depends on the rate of temporal increase of the perturbation amplitude as t > 0. The present study is closely related to the generation mechanism of the coherent vortical structures in the wall turbulence.
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David Blake, Robert E. Robson
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3556-3559
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
In a recent article [Yamamoto and Ikuta: J. Phys. Soc. Jpn.
68 (1999) 2602] state that the true origin of negative differential conductivity (NDC) has never been shown, in apparent contradiction of claims made in earlier papers [Z. Lj et al .: Aust. J. Phys.
37 (1984) 23; R. E. Robson:
ibid. 37 (1984) 35]. In the present paper, we argue that the true origin of NDC has indeed been explained satisfactorily, and present a comprehensive range of calculations for a number of cases, demonstrating the effectiveness of momentum transfer theory [
Hot electron transport in semiconductors (Springer, Berlin, 1985) p. 82] for understanding NDC from both a qualitative and quantitative perspective.
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Masaaki Matsukuma, Yoshinobu Kawai
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3560-3564
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The nonlinear saturation mechanism of the ion-ion instability is clarified. Amplitude oscillations is observed in an ion beam-plasma system with a mesh grid as a boundary condition. These amplitude oscillations are caused by multiple energy exchange between the unstable wave and trapped particles. Furthermore, the wave numbers estimated from the saturating length of ion-ion instability's wave-patterns are proportional to √V
m, where V
m represents a modulating amplitude of test waves. Thus it turns out that the ion-ion instability saturates due to particle trapping effect.
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Tomo-Hiko Watanabe, Hideo Sugama, Tetsuya Sato
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3565-3576
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
With the aim to study the ion temperature gradient (ITG) driven turbulence, a nondissipative kinetic simulation scheme is developed and comprehensively benchmarked. The new simulation method preserving the time-reversibility of basic kinetic equations can successfully reproduce the analytical solutions of asymmetric three-mode ITG equations which are extended to provide a more general reference for benchmarking than the previous work [T.-H. Watanabe, H. Sugama and T. Sato: Phys. Plasmas
7 (2000) 984]. It is also applied to a dissipative three-mode system, and shows a good agreement with the analytical solution. The nondissipative simulation result of the ITG turbulence accurately satisfies the entropy balance equation. Usefulness of the nondissipative method for the drift kinetic simulations is confirmed in comparisons with other dissipative schemes.
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Hiroyuki Kusuya, Akihiko Machida, Yutaka Moritomo, Kenichi Kato, Eiji ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3577-3580
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Temperature variation of the crystal structure has been investigated for Tb
2Ba
2Co
4O
11, which shows a metal-insulator (MI) transition at T
MI = 340 K. The compound has a layered-type double-perovskite structure along the c-axis, with alternating the CoO
6 octahedron and the CoO
5 pyramids along the a-axis. With decrease of temperature below T
MI, the distortion of the octahedral and pyramidal sites is fairly released, suggesting that spin state transition of the Co
3+ ions is the origin for the MI transition.
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Kwang-Sei Lee, Ill Won Kim
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3581-3584
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The differential scanning calorimetry and thermogravimetry of KHCO
3 indicate new transformation anomalies at 155 K (T
c2), 373 K (T
d) and 459 K. The former anomaly is likely to be caused by a structural phase transition, but the latter two anomalies are related to the thermal decomposition. The chemical reaction begins at about 373 K (T
d) and reaches a complete thermal decomposition of KHCO
3 into K
2CO
3 around 459 K. The experimental results are discussed in terms of protonic intrabond and interbond jump.
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Shin-ichi Furusawa, Takashi Kawaguchi
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3585-3590
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The temperature dependence of ionic conductivity of the AgI films on SiO
2 glass (quartz grass) substrates has been measured for various film thickness. AgI thin films showed conductivity enhancement, and the ionic conductivity shows an increase with decreasing the thickness. The experimental results suggest the existence of the high ionic conduction region at the SiO
2-AgI boundary. The thickness dependence of ionic conductivity of the AgI film was explained by a simple two layer model; high ionic conduction region and bulk ionic conduction region. Average ionic conductivity σ
λ and thickness λ of the high ionic conduction region at 300 K were estimated as 4.65 × 10
-5 Ω
-1cm
-1 and 0.28 μm, respectively.
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Shigeki Matsunaga
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3591-3595
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The molecular dynamics simulations are carried out in a liquid AuCs alloy. The electrical conductivities are obtained by using the equilibrium and non-equilibrium molecular dynamics methods, and these results agree well with experimental conductivities. The deviation from the Nernst-Einstein relation Δ is also derived by equilibrium molecular dynamics, using the partial conductivities σ
+ and σ
-, and the self diffusion coefficients D
+ and D
- of cations and anions, respectively. The obtained value of Δ is negative as that of molten AgI, potassium iodine and rubidium halides, which is related to the cross-correlation of ionic motion.
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Z. F. Li, B. X. Liu
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3596-3605
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Unique structural phase evolution was observed in the nano-sized Co-Cu multilayers upon solid-state reaction/ion beam mixing and resulted in the formation of several metastable phases in the equilibrium immiscible Co-Cu system. Despite of a positive heat of formation of the Co-Cu system, a superlattice was obtained in the nano-sized Co
34Cu
66 multilayered films upon 600 K thermal annealing, and it later evolved into a dodecagonal phase when the annealing temperature was risen up to 800 K. Comparatively, by ion beam mixing, other metastable phases were obtained,
e.g., an amorphous phase and a dodecagonal phase were obtained in the Co
15Cu
85 films. The same dodecagonal phase was also formed in the Co
50Cu
50 films and the ion mixed dodecagons tended to assemble themselves into a fourfold rotational symmetry at relatively high irradiation dose. In the present paper, thermodynamic modeling and the formation mechanism of the metastable phases were also discussed based on Miedima's model and consideration of the physical process driven far-from-equilibrium by ion beam mixing.
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Masaaki Nakamura, Kazuhito Itoh
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3606-3612
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Phase diagram of the one-dimensional extended Hubbard model with a nearest neighbor interaction V and site-off-diagonal (bond-charge X and bond-bond W) interactions at half-filling is obtained analytically and numerically. For the numerical analysis, we used the level-crossing approach which has been applied to the W=0 case [Phys. Rev. B
61 (2000) 16377]. Similarly to the X term, the W term enhances bond-charge-density-wave (BCDW) and bond-spin-density-wave (BSDW) phases for W<0 and W>0 cases, respectively. In addition, we showed that an exact ground state corresponding to a BSDW state, and an η-pairing ground state appear in this model.
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Takamitsu Ishihara, Hiroshi Yamagami, Hiroshi Yasuhara
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3613-3622
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Self-consistent band calculation of sodium is performed in the correlated Hartree-Fock scheme proposed by Yasuhara and Takada [Phys. Rev. B
43 (1991) 7200], which contains information on the effective mass of the electron liquid in the form of a nonlocal spin-parallel potential, and the remaining information of the self-energy operator in the form of a local potential. The bandwidth of occupied states is somewhat increased under the influence of the non-local spin-parallel potential, compared with the free electron value. No significant difference can be found in the distortion of the Fermi surface between the present theory and the LDA.
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Koujin Takeda, Ikuo Ichinose
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3623-3631
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
In this paper, one dimensional system of Dirac fermions with a random-varying mass is studied by the transfer-matrix method. We investigate the effects of nonlocal correlation of the spatial-varying Dirac mass on the delocalization transition. In particular, we numerically calculate both the “typical” and “mean” localization lengths as a function of energy and the correlation length of the random mass. To this end we introduce an imaginary vector potential as suggested by Hatano and Nelson and solve the eigenvalue problem. Numerical calculations are in good agreement with the results of the analytical calculations. We obtain a relation between the localization length of states and the correlation length of the random mass.
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Kentaro Nomura, Daijiro Yoshioka
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3632-3635
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The quasi-particle tunneling phenomena in the paired fractional quantum Hall states are studied. A single point-contact system is first considered. Because of relevancy of the quasi-particle tunneling term, the strong tunneling regime should be investigated. Using the instanton method it is shown that the strong quasi-particle tunneling regime is described as the weak electron tunneling regime effectively. Expanding to the network model the paired quantum Hall liquid to insulator transition is discussed.
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Yuo-Hsien Shiau, Chin-Kun Hu
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3636-3640
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We analytically study the photorefractive Gunn effect in n-GaAs subjected to two external laser beams which form a moving interference pattern (MIP) in the semiconductor. When the intensity of the spatially independent part of the MIP, denoted by I
0, is small, the system has a periodic domain train (PDT), consistent with the results of linear stability analysis. When I
0 is sufficiently large, the space-charge field induced by the MIP will compete with the PDT and result in complex dynamics, including driven chaos via quasiperiodic route.
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Tatsuya Yaguchi, Tsuneya Ando
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3641-3649
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Scattering of an electron wave by a cap is studied for several types of caps attached to a metallic armchair nanotube in an effective-mass approximation. The scattering phase shifts are expressed in terms of the shift in the boundary position and the effective phase shift at the boundary. The boundary shift is given by about 0.24 times the distance between the cap boundary and the cap tip, and the effective phase shift to be 0 and π for waves in the state with parity - and +, respectively.
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Moo-Sung Kim, Tetsuya Sasakawa, Toshiaki Suemitsu, Yoshio Bando, Kazun ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3650-3653
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We present the results of electrical resistivity ρ, Hall coefficient R
H, thermoelectric power S, specific heat C and magnetic susceptibility χ on SmBiPt with the MgAgAs-type structure. ρ(T) and S(T) exhibit a broad maximum of 1.7 mΩcm at 80 K and 60 μV/K at 126 K, respectively. These facts and the change of R
H from negative to positive on cooling through 200 K indicate the semimetallic nature of SmBiPt. At around 7 K, ρ(T) and S(T) show a shallow dip and a small peak, respectively. The antiferromagnetic order at T
N= 2.2 K is manifested as a sudden drop in ρ and a peak in both C and χ. The magnetic entropy at T
N is 0.6Rln4 and reaches a plateau of Rln4 at 18 K, indicating the Γ
8 quartet ground state of Sm
3+ in this cubic compound. The results of χ(T) and magnetization curve can be explained by considering the mixing of higher multiplet levels of J=7/2 and 9/2 into the ground multiplet of J=5/2.
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Rifki Muhida, Wilson Agerico Diño, Atsushi Fukui, Yoshio Miura, ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3654-3659
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We investigate the dynamics of o-p conversion of H
2 scattered from a 3d impurity sitting on a metal oxide surface. We treat Fermi's contact interaction (intra-molecular hyperfine contact interaction) and the H
2-surface electron exchange interaction (Coulomb interaction) as perturbations. Numerically, we calculate the o-p H
2 conversion yield as functions of the H-H bond orientation with respect to the surface normal and translational energy of H
2. We find that the o-p H
2 conversion yield decreases exponentially with increasing translational energy, and strongly depends on the H-H bond orientation with respect to the surface normal. The o-p H
2 conversion yield shows that a perpendicular orientation is preferred over a parallel orientation.
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Yoshiaki Sekine, Nao Takeshita, Nobuo Mori, Masahiko Isobe, Yutaka Ued ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3660-3666
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We developed a method of precise measurement of the dielectric constant under multi-extreme conditions, that is, under high pressures, high magnetic fields and low temperatures. We measured the dielectric constants and the magnetic susceptibility of single crystals of α
′-NaV
2O
5 under multi-extreme conditions. Anisotropic behavior of a relative dielectric constant was observed at the charge-ordering transition temperature under ambient pressure. With increasing hydrostatic pressure, the transition temperature decreased and another transition appeared below the first transition temperature. The susceptibility exhibited a sharp drop corresponding to the transition to the spin singlet state at the first transition temperature, while it showed no anomaly at the second transition temperature. These two transition temperatures were found to exhibit very weak magnetic field dependence in comparison with typical spin-Peierls compounds.
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Takehide Koyama, Masayuki Matsumoto, Shinji Wada, Yuji Muro, Masayasu ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3667-3672
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
A combination of the dense Kondo effect and Ruderman-Kittel-Kasuya-Yoshida interaction exhibited by an antiferromagnetic (AF) heavy-Fermion compound CeCuSb
2 (T
N=8 K) was investigated with the magnetic susceptibility χ and
63Cu magnetic resonance measurements in the temperature range between 1.4 and 210 K. For temperatures above ∼25 K, characteristics of the localized 4f spins are observed in the Curie-Weiss-type behavior of the Knight shift K and the strongly enhanced relaxation rate T
1-1. For the temperature below ∼25 K, the χ data tend toward a constant value, which is an indication of the onset of the heavy-Fermion state. The slope of the Knight shift versus susceptibility (K-χ) plots decreases below ∼100 K, which is ascribed to the difference in the anisotropic hyperfine coupling to the crystal-field-split Γ
7 (ground state) and Γ
8 (excited state) wave functions of the Ce ions. The K-χ plots below ∼25 K exhibit another deviation from the linearity in opposite direction. We speculate that this is caused by the spin polarization of the conduction electron cloud associated with the Kondo-like compensation of the Ce's 4f moment. The low-temperature increase of T
1-1 is conjectured to the development of short range magnetic ordering at temperatures well above T
N. Below T
N, we observed a large anisotropic broadening of the resonance line and an abrupt decrease of T
1-1. The experimental values of the linewidth for T«T
N and the hyperfine field give a measure of the partial moment compensation by about 23%, which can reasonably be compared with the small magnetic entropy S
mag of 0.7ln2. In a related superconducting compound LaCuSb
2 (T
SC=0.9 K), on the other hand, both of K and (T
1T)
-1 for each of
63Cu and
121Sb exhibit near temperature-independent behavior of the normal Fermi liquid, and the small values are indicative of rather low density of carriers.
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Kazuo Hida
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3673-3677
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The magnetization process of the S=1 and 1/2 kagomé Heisenberg antiferromagnet is studied by means of the numerical exact diagonalization method. It is found that the magnetization curve at zero temperature has a plateau at 1/3 of the full magnetization. In the presence of √3 × √3 lattice distortion, this plateau is enhanced and eventually the ferrimagnetic state is realized. There also appear the minor plateaux above the main plateau. The physical origin of these phenomena is discussed.
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Takahiro Yamamoto, Masanari Asano, Chikara Ishii
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3678-3682
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The magnetization process of one-dimensional Kondo necklace model with next-nearest-neighbor interaction has been studied by the use of exact-diagonalization method. The magnetization plateaus appear at zero (m=0) and at half (m=1/2) of the saturation magnetization. The ground state in the absence of a magnetic field is regarded as an aggregate of intra-atomic Kondo singlets. On the other hand, the spin configuration at the 1/2-plateau represents the intra-chain dimer (σ-dimer) phase with broken translational symmetry. The picture for spin configurations in the uniform magnetic fields other than m=0 and 1/2 are also given. We also determined the phase diagram for the ground state of the system in the magnetic field.
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Taichi Terashima, Shinya Uji, Haruyoshi Aoki, Jeremy S. Qualls, James ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3683-3689
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Although the crystal-field ground state in the paramagnetic phase of CeP is Γ
7, part of cerium ions take a Γ
8-like state in magnetically ordered phases and regular arrangements of the Γ
7 and Γ
8-like moments constitute magnetic structures. We have performed transverse magnetoresistance measurements up to 32 T for selected field directions and have determined phase boundaries related to the appearance of the Γ
8-like state for each field direction. The result reveals the extreme uniaxial anisotropy that the Γ
8-like moment is strongly bound to the [001] axis. We have also determined the field-orientation dependence of phase transitions connected with the rearrangement of the Γ
7 moment via ac susceptibility measurements. The analysis of the angular dependence indicates that the Γ
7 moment prefers the [001] direction only weakly probably due to the exchange field from neighboring Γ
8 moments. The resistivity exhibits a sharp decrease on the appearance of the Γ
8-like state. Besides, Hall effect measurements up to 26 T show a concomitant reduction of the magnitude of the Hall coefficient, and suggest the presence of the anomalous Hall effect in the magnetically ordered phases. These indicate that the appearance of the Γ
8-like state is accompanied by a drastic change of the electronic structure.
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Naokazu Shibata, Kazuo Ueda
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3690-3694
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Thermodynamic properties of the S=1/2 Heisenberg chain in transverse staggered magnetic field H
sy and uniform magnetic field H
x perpendicular to the staggered field is studied by the finite-temperature density-matrix renormalization-group method. The uniform and staggered magnetizations and specific heat are calculated from zero temperature to high temperatures up to T=4J under various strength of magnetic fields H
sy and H
x. The specific heat and magnetization of the effective Hamiltonian of the Yb
4As
3 are also presented, and field induced gap formation and diverging magnetic susceptibility at low temperature are shown.
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Takuya Arimori, Hikaru Kawamura
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3695-3707
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Ordering of the geometrically frustrated two-dimensional Heisenberg antiferromagnet on a pyrochlore slab is studied by Monte Carlo simulations. The model is expected to serve as a reference system of SrCrGaO compound studied extensively. In sharp contrast to the kagomé Heisenberg antiferromagnet, the model exhibits locally non-coplanar spin structures at low temperatures, bearing nontrivial chiral degrees of freedom. We find that under certain conditions the model exhibits a novel Kosterlitz-Thouless-type transition at a finite temperature associated with these chiral degrees of freedom. Implications to experiments are discussed.
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Ae Ran Lim, Jae Kap Jung, Hyun Min Park
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3708-3712
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The
1H and
87Rb NMR spin-lattice relaxation times for a RbHSO
4 single crystal were measured in the temperature range of 300-170 K for study of the paraelectric (I) to ferroelectric (II) phase transition near T
c=264 K. Proton spin-lattice relaxation time on the RbHSO
4 yielded a minimum, attributed to the effect of molecular motion. The activation energy for the reorientational motion in phase I was determined to be 16.54 kJ/mol, whereas, for the molecular motion in the phase II it was 25.53 kJ/mol. The change of the
87Rb spin-lattice relaxation rate near 264 K corresponds to a phase transition in the crystal. The temperature dependences of the relaxation rate for
87Rb in this crystal were in accordance with the single phonon process dominated by the phonon mechanism. The activation energies in phases I and II were obtained to be 2.66 kJ/mol and 17.25 kJ/mol, respectively. From
1H and
87Rb NMR investigations, the phase transition does play an important role by Rb nucleus, although the activation energy obtained by
1H relaxation time is higher than that obtained by
87Rb relaxation time.
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Takahiro Sunaga, Midori Tanaka, Nobuhiko Sakai, Yorihiko Tsunoda
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3713-3718
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Mössbauer spectra of a single crystal of LuFeCoO
4 are studied in the temperature range between 4.2 K and 70 K. The Mössbauer spectra are separated into two components. We propose a model that one of three spins in a spin plane is parallel to the c-axis and other two orient to 120
º to the c-axis. This model explains the experimental data satisfactory. It is concluded that the spins parallel to the c-axis are more stable than the other when temperature is increased. The Ising like character observed in susceptibility measurements can be explained by this spin arrangement in the spin planes.
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Jai Hoon Lee, Sam Nyung Yi, Sang Don Choi
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3719-3722
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Continued fraction representation is reviewed in magneto-optical transition of electrons in semiconductors interacting with acoustic phonons in the quantum limit. The representation is obtained by utilizing Mori's projectors and is changed into the power series form in the lowest order approximation. The expansion parameter appearing in the transformation is examined with focus on the difference between the piezoelectric scattering and the deformation potential scattering. In the present choice of expansion, the parameter for CdS and GaAs decreases monotonously with temperature, unlike for Ge and Si, for which the parameter is a common constant.
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Seongtae Park, Ilgon Kim, Kiwan Jang, Sangsu Kim, C. D. Kim, Yongil Ye ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3723-3727
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
We fabricated CuCl quantum dots (QDs) in a glass matrix. The blue shift of the exciton spectrum caused by quantum confinement effects was observed in the linear absorption and the photo-luminescence (PL) spectrum. Inhomogeneous line broadening was mainly induced by the size distribution of CuCl QDs and we found that the size distribution has Gaussian profiles. By solving the steady state rate equation, we also found that the intensities of biexciton PL were proportional to the square of exciton PL intensities, and the results were well accorded with the experimental results. The formation rates of biexciton were proportional to the volumes of CuCl QDs.
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Mikhail Maksimuk, Kyuya Yakushi, Hiromi Taniguchi, Kazushi Kanoda, Ats ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3728-3738
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
The C=C stretching modes in resonance Raman spectra and infrared reflectivity were measured at temperatures between 15 K and 300 K using various polarizations in κ-(BEDT-TTF)
2Cu[N(CN)
2]Br, its fully and partially deuterated analogues, and
13C-substituted analogue. The infrared- and Raman-active bands were re-assigned based on the factor group analysis. We found a Raman-active EMV-coupled ν
3 mode near 1420 cm
-1, which shows a large downshift and broadening through the inter-dimer EMV interaction. The mixing of the bridge and ring C=C stretching vibrations depend upon the symmetry of the crystal mode. In contrast to deuterated crystals, the non-deuterated crystals show a splitting in the ν
2, ν
3, and ν
27 bands.
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Akihiko Machida, Yutaka Moritomo, Kenji Ohoyama, Arao Nakamura
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3739-3746
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Crystal and magnetic structures of Tb
1-xCa
xMnO
3 (x ≥ 0.5) have been investigated by means of neutron powder diffraction experiments. We have derived the magnetic phase diagram against hole concentration x and temperature T: the spin structure changes as CE- → C- → G-type structure with increase of x. In the vicinity of the magnetic phase boundaries, magnetically phase separated state has been observed. At high temperature region, we observe the metallic behavior in a wide x region (0.70 ≤ x ≤ 0.95), and ascribe it to the enhanced one-electron bandwidth W of the e
g state.
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Yoshihiro Ishibashi, Minoru Fukui
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3747-3750
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
Cell automaton simulations have been performed for the traffic flows on two one-lane roads, crossing at a point, where the maximum velocities of the northbound and the eastbound cars are different. The phase diagrams are constructed, and it has turned out that the phase diagrams consist of six regions. The obtained phase diagrams are interpreted on the basis of the local occupation probability method.
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Shin-ichi Kondo, Kazuhiro Amaya, Tadaaki Saito
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3751-3752
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
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Kiyohiro Sugiyama, Motoki Futoh, Tomoya Iizuka, Takao Ebihara, Tetsuta ...
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3753-3754
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
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Teruhisa S. Komatsu
原稿種別: General Physics
専門分野: Mathematical methods in physics.
2001 年 70 巻 12 号 p.
3755-3756
発行日: 2001年
公開日: 2003/02/28
ジャーナル
認証あり
