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Hiroshi Tsukahara, Takeo Inami
Subject area: Statistical physics and thermodynamics.
1998 Volume 67 Issue 4 Pages
1067-1070
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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We investigate the analyticity property of the partially resummed series expansion (PRSE) of the partition function for the eight-vertex model. By developing a graphical technique, we have obtained the first few terms of the PRSE and found that these terms have a pole only at one point in the complex plane of the coupling constant.This result supports the conjecture proposed by Guttmann and Enting concerningthe “solvability” in statistical mechanical lattice models.
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Akinori Awazu
Subject area: Fluid dynamics.
1998 Volume 67 Issue 4 Pages
1071-1074
Published: April 01, 1998
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A simple two-lanes traffic flow model using cellular automaton isinvestigated.In this model, if the car density is set within a certain range, the following characteristic behavior of traffic flow is observed.i) The self-organization of the slow and fast lanes in spite of the symmetrybetween these two lanes. ii) The appearance of several branches and hysteresis in the relation between traffic flow and car density.
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Yukio Kaneda, Koji Gotoh, Takashi Ishihara
Subject area: Fluid dynamics.
1998 Volume 67 Issue 4 Pages
1075-1078
Published: April 01, 1998
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The time-derivatives up to the 6th-orderof Eulerian and Lagrangian velocity fieldsin homogeneous and isotropic turbulence are computed. The Taylor expansions in powers of the time difference of the Eulerian as well as the Lagrangian two-time velocity correlations, and their Padé approximationsare constructed from the time-derivatives.The Padé approximations are found to be in good agreement withdirect numerical simulations.
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Yoshihiro Kazimura, Francesco Califano, Jun–ichi Sakai, Torsten ...
Subject area: The physics of plasmas and electric discharges.
1998 Volume 67 Issue 4 Pages
1079-1082
Published: April 01, 1998
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We present the results of analytical studies and computer simulationsof electron-ion plasma cloud collisions using 2D3Vparticle-in-cell and 2D two-fluid collisionless relativistic codes. We address the problem concerning the generation of a quasistaticmagnetic field. Using relativistic two-fluid equations for the twocounterstreaming electron populations, we show with the help of lineartheory that the generation of a magnetic field can beassociated with the “electromagnetic counterstreaminginstability”. Two-dimensional (2D) particle-in-cell provide goodagreement with the results of linear theory. We show that the quasistatic magnetic field undergoes a collisionless change ofstructure, leading to large-scale, long-lived structures. These processesmay be important for the understanding of magneticfield generation in laser plasmas and in space plasmas in the regions wheretwo stellar winds collide.
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Manabu Ikebe, Hiroyuki Fujishiro, Yoshiyuki Konno
Subject area: Thermal properties of condensed matter.
1998 Volume 67 Issue 4 Pages
1083-1085
Published: April 01, 1998
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The temperature dependence of the phonon thermal conductivity κ (T) of La
1-xSr
xMnO
3 (0.11≤ x≤ 0.20) polycrystals was measured from 60, K to 360, K. For x=0.155 and 0.170, κ (T) is markedly reduced over a wide temperature range near the ferromagnetic transition temperature T
c. The analyses of κ (T) have revealed the existence of anomalously strong phonon scattering caused by the coupling of spin fluctuations and the lattice instability in this double exchange coupled system.
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Naokazu Shibata, Beat Ammon, Matthias Troyer, Manfred Sigrist, Kazuo U ...
Subject area: Thermal properties of condensed matter.
1998 Volume 67 Issue 4 Pages
1086-1089
Published: April 01, 1998
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Thermodynamic properties of the one-dimensional Kondo lattice model at half-filling are studied by the density matrix renormalization group method applied to the quantum transfermatrix. Spin susceptibility, charge susceptibility, and specific heat are calculated down to T=0.1t for various exchange constants. The obtained results clearly indicate crossover behavior fromthe high-temperature regime of nearly independent localized spinsand conduction electrons to the low-temperature regime where the two degrees of freedom couple strongly.The low-temperature energy scales of the charge and spin susceptibilities are determined and are equal to the quasiparticle gap and the spin gap, respectively, for weak exchange couplings.
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Gen Tatara, Makoto Kikuchi, Satoshi Yukawa, Hiroshi Matsukawa
Subject area: Transport properties of condensed matter (nonelectronic).
1998 Volume 67 Issue 4 Pages
1090-1093
Published: April 01, 1998
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Quantum mechanical motionof a particle in a periodic asymmetric potential is studied theoreticallyat zero temperature.It is shown based on a semi-classical approximation thatthe tunneling probability from one local minimum to the nextbecomes asymmetric in the presence of a weak oscillating field, even though there is no average macroscopic field gradient.Dissipation enhances this asymmetry, and leads to a steady unidirectional current, resulting in a quantum ratchet system.
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Ming–Fa Lin
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1094-1097
Published: April 01, 1998
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Persistent currents in thin toroidal carbon nanotubes (TCN's)are linearly periodic functions of magneticflux (φ) with a period φ
0 (hc/e). This result is amanifestation of the Aharonov-Bohm (AB) effect.They depend on the toroid structure(such as curvature, radius, and height), the temperature, and the Zeeman effect.The curvature effect due to the misorientation of π-electron orbitalsaffects the electronic states, and thus the persistent current.Consequently, most of armchair-zigzag TCN's exhibit diamagnetism.The current amplitude is inversely proportional to the toroid radius.A temperature increase significantly reduces the persistent current, whilethe periodicalAB oscillation remains unchanged.Measurements of the persistent currents could be used to verifythe predicted electronic states and the AB effect.
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Nobuko Kobayashi, Masao Ogata, Kenji Yonemitsu
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1098-1101
Published: April 01, 1998
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We have performed a mean field calculation in order to determinethe ground state of a modified Hubbard model of a quarter-filledone-dimensional chain.It is found that the coexistence of 2k
F spin density wave (SDW)and purely-electronic 2k
F charge density wave (CDW)is realized due to the effect of next-nearest-neighbor Coulomb repulsion.Phase diagrams are obtained as the values of nearest- and next-nearest-neighborCoulomb interaction energies are varied.Competition between the two coexistent states with 2k
F CDW and4k
F CDW is revealed, which gives a first order transition.Our result supports the X-ray resultconfirming the presence of a coexisting phase ofpurely-electronic 2k
F CDW and 2k
F SDW in (TMTSF)_2PF_6, a quarter-filled one-dimensional chain in terms of holes.
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Hiroyuki Yamaguchi, Takayuki Ito, Taizo Masumi
Subject area: Electronic transport in condensed matter.
1998 Volume 67 Issue 4 Pages
1102-1105
Published: April 01, 1998
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Hall mobility μ
H of photocarriers in pure CuO refined by floating zone melting (FZ) method has been studied by adopting a pulsed technique for photoconductivity measurements between T=25, K and 110, K. Dominant photocarriers turn out to be positive holes. Value of μ
H of holes increases with decreasing T and reaches 8× 10
3, cm
2, V
-1, s
-1 at 25, K. Scattering mechanisms of photocarriers are due to the high-frequency LO-phonon, acoustical phonon and neutral impurity. The experimental results on the temperature dependence and the absolute value of μ
H(T) clearly indicate that a relatively wide valence band may exist in CuO, where large polarons are mobile.
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Kazunori Aoki, Suguru Fukui
Subject area: Electronic transport in condensed matter.
1998 Volume 67 Issue 4 Pages
1106-1109
Published: April 01, 1998
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The nucleation process of a current filament has been investigated in n-GaAs during the impact ionization avalanche of neutral shallow donors at 4.2, K. The image patterns of the current filament are measured under a pulsed electric field with the pulse width T
p by detecting quenched patterns of photoluminescence from the laser-excited sample. It is found that the rudimentary filament is formed with the pulse width T
p=900, ns and the pulse height V
p=0.79, V. Fronts of the nucleated filament at the cathode (or the anode) propagate towards the anode (or the cathode). Drift velocity and drift mobility of the fronts are estimated as a function of the pulse width. We also investigate the nucleation process under the transverse magnetic field.
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Shinji Kawaji, Junji Suzuki, Takako Shimada, Hisamitsu Iizuka, Takeshi ...
Subject area: Electronic transport in condensed matter.
1998 Volume 67 Issue 4 Pages
1110-1113
Published: April 01, 1998
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Collapse of quantized Hall resistance (QHR), not resulting from breakdown of the dissipationless current flow, is reported in the integer quantum Hall effect (IQHE) state with i=4 of GaAs/Al
0.3Ga
0.7As butterfly-type Hall bars at high Hall electric fields. The Hall electric field F
H at the collapse of QHR is about 20% lower than the F
h for the breakdown of the dissipationless current flow. The nature of difference between the effect of the F
H on the collapse of QHR and the effect of the F
H on the breakdown is discussed.
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Shigeru Koikegami, Kosaku Yamada
Subject area: Superconductivity.
1998 Volume 67 Issue 4 Pages
1114-1117
Published: April 01, 1998
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We study the superconducting transition temperature T
c of thebilayer d-p model with d
x2-y2-wavelike attractiveinteraction based on the formalism first employed by Nozières andSchmitt-Rink. In the strong coupling regime, T
c obtained through this formalism are much suppressed, compared with those through Thouless criterion only. We also find that, whether the interlayer coupling exsists or not, T
c is almost propotional to the Fermi energy E
F in the strong coupling regime. Thus, we can reproduce the essential nature in the underdoped region.
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Yasunari Tanuma, Yukio Tanaka, Masao Ogata, Satoshi Kashiwaya
Subject area: Superconductivity.
1998 Volume 67 Issue 4 Pages
1118-1121
Published: April 01, 1998
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Spatial dependencies of the pair potentialand the local density of states near the surfacesof d
x2-y2-wave superconductors are studied theoretically.The calculation is based on the t-J model within a mean-field theory with Gutzwiller approximation.Various types of surface geometries are considered.Similar to our result in the extended Hubbard model, it is found that the formation of zero-energy states strongly depends on the surface geometry. In addition to this feature, the zero-energy states give peak splitting for the (110) surfaceswhen the super-exchange interaction J is large.This is due to the induced s-wave component near the surface.The present result explains the microscopic origin ofthe spontaneous time-reversal symmetrybreaking at the surfaces of high-T
c superconductors.
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Kazushige Machida, Tetsuo Ohmi
Subject area: Superconductivity.
1998 Volume 67 Issue 4 Pages
1122-1125
Published: April 01, 1998
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A NMR experiment recently done on a heavy Fermion superconductor UPt_3 is interpreted in terms of a nonunitary spin-triplet pairing state which we have been advocating. The proposed state successfully explains various aspects of the seemingly complicated Knight shift behaviors probed for major orientations, including a remarkable d-vector rotation under weak fields. This makes UPt_3the first example of a charged many-body system forming a spin-tripletodd-parity pairing at low temperatures, which demonstrates definitivelythat the putative spin-orbit coupling in UPt_3 is weak.
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Hiroki Nakano, Minoru Takahashi
Subject area: Magnetic properties and materials.
1998 Volume 67 Issue 4 Pages
1126-1129
Published: April 01, 1998
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We study the one-dimensional S=1 spin system with interactions up to the next-nearest-neighbor pairs and the single-ion anisotropy and present a case when the system has a plateau half the height of the saturated magnetization in the magnetization process. In this system, the origin of the plateau is the triplet-dimer state, which has a periodicity different from that of the Hamiltonian. We develop a variational argument and find that it describes both edges of the plateau well.
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Kenji Harada, Matthias Troyer, Naoki Kawashima
Subject area: Magnetic properties and materials.
1998 Volume 67 Issue 4 Pages
1130-1133
Published: April 01, 1998
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The temperature dependence of the correlation length, susceptibilitiesand the magnetic structure factor of the two-dimensional spin-1 squarelattice quantum Heisenberg antiferromagnet are computed by the quantumMonte Carlo loop algorithm (QMC). In the experimentally relevant temperatureregime the theoretically predicted asymptotic low temperature behavioris found to be not valid. The QMC results however, agree reasonably wellwith the experimental measurements of La_2NiO_4 even withoutconsidering anisotropies in the exchange interactions.
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Junya Sasaki, Fumitaka Matsubara
Subject area: Magnetic properties and materials.
1998 Volume 67 Issue 4 Pages
1134-1137
Published: April 01, 1998
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We have performed a Monte Carlo simulation of an isotropic Heisenberg antiferromagnet with dipolar interactions on the triangular lattice.The model exhibits three phase transitions at T
KT1, T
KT2 and T
c.A Kosterlitz-Thouless-like phase of the spins initially appears at T
KT1 and disappears at T
KT2.The low-temperature phase occurring below T
c is a long-range ordered phase which is characterized by the ordering of the chiral vectors for every plaquette and the exponential decay of the spin correlation.This novel phase is realized as the result of the cooperation between the exchange and dipolar interactions.
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Yoshiaki Saito, Koichiro Inomata
Subject area: Magnetic properties and materials.
1998 Volume 67 Issue 4 Pages
1138-1141
Published: April 01, 1998
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Magnetoresistance was investigated in Fe/FeSi/Fe sandwiches with metallic bcc- and semiconductor like FeSi spacers prepared by an ultrahigh-vacuum magnetron sputtering system, enhanced with inductively coupled RF plasma. In the easy axis direction, MR curves at 298 K have a dip around the zero magnetic field for both Fe/FeSi/Fe sandwiches with semiconductor like FeSi and bcc metallic FeSi spacers. On the other hand, MR curves at 10 K exhibit a dip and no anomaly around the zero magnetic field for the Fe/bcc metallic FeSi/Fe and Fe/semiconductor like FeSi/Fe sandwiches, respectively. When the contribution of biquadratic coupling to interlayer exchange coupling is considered, these MR behaviors are well explained. These results support the interlayer exchange coupling model attributed to the biquadratic exchange coupling which outweighs the colinear term at a low temperature in Fe/FeSi multilayers.
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Yoshihiro Koike, Naoto Metoki, Noriaki Kimura, Etsuji Yamamoto, Yoshin ...
Subject area: Magnetic properties and materials.
1998 Volume 67 Issue 4 Pages
1142-1145
Published: April 01, 1998
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Ultralow-temperature neutron scattering experiments have been carried out in order to study the antiferromagnetic ordering in the heavy fermion superconductor UPt_3. We observed the (0.5 0 1) antiferromagnetic peak below 5 K. We found a finite spin correlation length of about 300 Å above 50 mK. The peak intensity increases linearly with decreasing temperature, and is suppressed below the superconducting transition temperature of about 0.56 K. The moment size of 0.04 μ
B/U was estimated from the peak intensity. These behaviors are in full agreement with results of previous studies. Surprisingly, the antiferromagnetic peak exhibits considerable narrowing below 50 mK, and a resolution-limited peak is observed below 20 mK. This is direct evidence that the antiferromagnetic long-range ordering is realized in UPt_3 at ultralow temperatures.
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Masayuki Kawakami
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1998 Volume 67 Issue 4 Pages
1146-1149
Published: April 01, 1998
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A transferred hyperfine field H
thf1 of the type Mrf(r)/r which a Ce magnetic moment produces at
11B nuclei in CeB
6 is proposed, in order to explain the angular dependence of the
11B resonance magnetic field in phase II of the compound. Here, M is the uniform component of the Ce magnetic moments induced by the applied field, and r is the position vector from a Ce site to a B site at which H
thf1 is produced. A crystal deformation is suggested for this type of H
thf1 to occur.
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Effat Abbas Saied
Subject area: Mathematical methods in physics.
1998 Volume 67 Issue 4 Pages
1151-1156
Published: April 01, 1998
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This paper classifies all point transformations of a general class between generalized nonlinear diffusion-convection equations of the form f(x)u
t=E(x, , u, , u
x)x and E(x, , u, , u
x)=g(x)D(u)u
x+H(u). These transformations depend on the functional form of the functions D(u), H(u), f(x), and g(x). Some new exactly linearizable forms are determined and solved by using Lie group method.
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Tetsu Yajima, Katsuhiro Nishinari
Subject area: Mathematical methods in physics.
1998 Volume 67 Issue 4 Pages
1157-1162
Published: April 01, 1998
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Initial-boundary value problems for the Davey-Stewartson type I equation are solved exactly. When the initial localized pulse can be expressed as a product of functions of a single variable, the quantity which characterizes the pulse in the final stage is derived as a function of the parameters appearing in the initial and boundary conditions. The ratio of the volume of ripple to the volume of the initial wave packet is also investigated. The amount of ripples generated from the initial condition is found to be an increasing function of the volume of the initial pulse.
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Rei Inoue, Kazuhiro Hikami
Subject area: Mathematical methods in physics.
1998 Volume 67 Issue 4 Pages
1163-1174
Published: April 01, 1998
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We study the dynamical system on the space-time latticebased on solutions of the Yang--Baxter equation.We construct the quantum integrable difference-difference equationsassociated with the lattice W
N algebra.The classical lattice system and its time continuous limit are also discussed.
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Takayuki Tsuchida, Miki Wadati
Subject area: Mathematical methods in physics.
1998 Volume 67 Issue 4 Pages
1175-1187
Published: April 01, 1998
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Generalization of the modified KdV equation to a multi-component system, that is expressed by\frac{∂ u_i}{∂ t} + 6 \bigl( ∑_{j, k=0}
M-1 C
jk u_j u_k \bigr)\frac{∂ u_i}{∂ x} + \frac{∂^3 u
i}{∂ x^3} =0, i=0, 1, …, M-1, is studied.We apply a new extended version of the inverse scattering method tothis system. It is shown that this system has an infinite number of conservation laws and multi-soliton solutions. Further, the initial value problem of the model is solved.
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Nobuyasu Ito, Takashi Matsuhisa, Hidetsugu Kitatani
Subject area: Statistical physics and thermodynamics.
1998 Volume 67 Issue 4 Pages
1188-1196
Published: April 01, 1998
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The ferromagnetic transition of ± J-Ising spin-glass modelon square lattice is studied by using Monte Carlo simulation. At ferromagnetic-bond density p=0.96 where thesystem shows ferromagnetic transition, the spontaneous magnetization, the ratio ‹ m
4 › / ‹ m
2›
2 and the non-equilibrium relaxation (NER) are studied. The transition is estimated to be at K_c=0.5100 (1). The analysis by NER gives the most reliable estimationwith the least CPU time for simulations among the three methods. Thevalue of magnetization exponent β is estimated to be 0.130(10) which coincides with that of the purely ferromagnetic Isingmodel (p=1). The dynamical critical exponent z is estimated to be 2.418(23)from the NER analysis which is different from that of the pure model. The size of simulated lattices is up to 2001× 2000, andthe number of totally updated Ising spins is 5.5× 10
15.
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Takeya Tsurumi, Miki Wadati
Subject area: Statistical physics and thermodynamics.
1998 Volume 67 Issue 4 Pages
1197-1200
Published: April 01, 1998
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We investigate the singularity of the magnetically trapped Bose-Einstein condensate with attractiveinteratomic interactions. By using a model equation, three-dimensional attractive nonlinear Schrödinger equation with anisotropic harmonic potential terms, we show the scaling laws for the system near the singularity.We also discuss the self-similar behavior of the wavefunction in detail.
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Bhartendu K. Singh, Shrawan K. Tuli
Subject area: Specific reactions and phenomenology.
1998 Volume 67 Issue 4 Pages
1201-1206
Published: April 01, 1998
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Results from measurement of multiplicity of different charged particles emitted from the interactions of 3.7, A, GeV
28Si with different target groups in nuclear emulsion and correlations among them are presented. The nature of the dependence of multiplicities of charged particles on the impact parameter is examined. Analysis of data in terms of specific multiplicity for different target groups is performed and the results are discussed in the light of superposition model.
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Takashi Taneichi, Takayoshi Kobayashi
Subject area: Atomic spectra and interactions of atoms with photons.
1998 Volume 67 Issue 4 Pages
1207-1212
Published: April 01, 1998
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An atom-cavity field interaction scheme between Jaynes-Cummings (JC) and Weisskopf-Wigner (WW) model is varied by changing the cavity-mode density which is dependent on the cavity size. In order to see this, excited state dynamics of a two-level atom in a one-dimensional cavity is studied. Cavity modified quantum beat realized in a three-state atom inside a cavity is also discussed.
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Takeshi Kuwamoto, Ichita Endo, Atsushi Fukumi, Takayoshi Horiguchi, Ma ...
Subject area: Atomic spectra and interactions of atoms with photons.
1998 Volume 67 Issue 4 Pages
1213-1219
Published: April 01, 1998
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Hyperfine structures, isotope shifts, Stark and Zeeman effects of 5transitions in Sm {2pt}{\captionsize I} are investigatedby means of atomic-beam laser spectroscopy. We measure the transitions from 10801.10- and 12313.11-cm
-1 metastablelevels with 4f^65d6s configuration to 27925.31-, 28704.25-, 29041.31-and 30753.65-cm
-1 odd-parity levels, which are candidates in order tomeasure parity nonconserving effect in Sm.Hyperfine constants A and B for odd-mass isotopes
147Sm and
149Sm are obtained except for 30753.65-cm
-1 level.Isotope shifts of the transitions are determined and specific mass shift andfield shift are also derived by King-plot analysis. Stark splitting is resolved for the transition between 12313.11- and30753.65-cm
-1 levels, and the tensor polarizability of the upperlevel is determined to be α_2 = 535(12) kHz/(kV/cm)^2.From Zeeman splitting, g-factors are precisely determined for 4 levels.
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Arathi Rani Santhamurthy, Tetali A. Prasada Rao, Jandhyala Sobhandri, ...
Subject area: Experimentally derived information on atoms and molecules: instrumentation and techniques.
1998 Volume 67 Issue 4 Pages
1220-1225
Published: April 01, 1998
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The technique of time resolved microwave dielectric absorption has been used to study the excited triplet states formed by the laser flash photolysis. The details of the experimental method and apparatus are discussed. The triplet state lifetimes and triplet state dipole moments of fluorenone and its derivatives are reported. The triplet state lifetime of fluorenone agrees with that obtained by optical absorption. The lifetime measurements with argon purging and with air equilibrated solution confirm the formation of triplet states. A marked increase in the triplet state dipole moment of fluorenone and its derivatives is observed and implies that their lowest triplet state is of (π, , π
*) in nature.
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Takeshi Miyazaki, Alexander Lifschitz
Subject area: Fluid dynamics.
1998 Volume 67 Issue 4 Pages
1226-1233
Published: April 01, 1998
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Standing plane waves in a rigidly rotating ideal fluid are considered. It is shown that all of them are unstable with respect to three-dimensional perturbations. When the amplitude of standing waves is small, the growth rate of the instabilities increases as their wavenumber increases. It approaches the value predicted by a WKB analysis (Lifschitz & Fabijonas 1996) from below. The most dangerous modes are concentrated near the node-planes of the basic flow field.For long wavelength disturbances of small amplitude inertial waves resonant triad instabilities are observed.
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Yoshiyuki Tsuji, Brindesh Dhruva
Subject area: Fluid dynamics.
1998 Volume 67 Issue 4 Pages
1234-1242
Published: April 01, 1998
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Instantaneous shear stress fluctuation is considered for different kinds of flow fields and Reynolds numbers. These fluctuations consist of intermittent sharp spikes and small scale oscillations around the zero-crossing. We introduce the maximum norm to characterize them. This norm is defined as a largest change within a box of finite size. The experimental results indicate that the maximum norm has a power law distribution in the inertial range. This distribution is independent of the flow field and the Reynolds number. Analogous to the locally averaged energy dissipation rate, the intermittency exponent μ is obtained for the maximum norm. Within experimental scatter, we find 0.1 ≤ μ ≤ 0.15. This value is a little smaller than that for the energy dissipation field.
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Hideaki Kitauchi
Subject area: Fluid dynamics.
1998 Volume 67 Issue 4 Pages
1243-1249
Published: April 01, 1998
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Topological structure and reconnection of magnetic flux lines are investigated by analyzing the numerical solutionof the Boussinesq magneto-hydrodynamic equationsin a rotating spherical shell.Five pairs of Taylor-Proudman vortex columns are generatedand drift westward steadily.Magnetic field is intensified around the tops of these vortex columns.Magnetic flux linesconnect east-west adjacent domains of intense magnetic field, which migrate eastward relative to the vortex columns.We describe the variation of topology of magnetic flux linesassociated with this eastward migration.
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Koichi Noguchi, Tadatsugu Hatori, Tomokazu Kato
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1998 Volume 67 Issue 4 Pages
1250-1259
Published: April 01, 1998
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We analyze the stability based upon linearized ideal reduced MHD equations.It is shown that abrupt spatial change of a vorticity gives rise to the Kelvin-Helmholtzinstability while electric current suppresses the instability.We obtain analytically the criteria for a uniform current case, a uniform vorticity case, and a vortex-current filament case.For less restricted cases, we solve the dispersion relation numerically.Threshold of the Kelvin-Helmholtz instability depends on the azimuthal mode numberm and the parallel component of wave vector k_//.We also show that the vorticity, which leads to the Doppler-shift, modifies the Alfvén continuum and the criterion of the kink instability.
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Takahumi Miyazaki, Retsuo Kawakami, Nobuaki Ikuta
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1998 Volume 67 Issue 4 Pages
1260-1272
Published: April 01, 1998
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A set of systematic calculations for the ion transport properties under repulsive potentials in the form A· r
-n for n=4, 8 and ∞ has been performed to understand the effects of the ion-neutral mass ratio. Obtained data for three mass ratios 1/1, 1/4 and 4/1 at each of 100 and 300, K over a wide range of the reduced electric field show complex but consistent mass ratio dependences. The effects of mass ratios on the variation of ion mobilities are discussed in relation with the change of mean collision frequencies.
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Haruhisa Koguchi, Masaru Masuzaki, Ritoku Ando, Keiichi Kamada
Subject area: The physics of plasmas and electric discharges.
1998 Volume 67 Issue 4 Pages
1273-1280
Published: April 01, 1998
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Our recent works, which were based on the spectroscopic measurement of strong high frequency electric fields in a plasma, showed that the plasma became a strong Langmuir turbulence state when an intense relativistic electron beam was injected into it. To further confirm this the energy spread and the perpendicular velocity scattering of beam electrons after passing the plasma were measured as well as the strong high frequency electric fields and the electron temperature. The theory of transit-time interactions which deals with the beam scattering in strong Langmuir turbulence was applied to interpret the experimental data. The result again shows that the plasma becomes a strong Langmuir turbulence state. The broadband microwave radiation was also observed simultaneously with the measurement of the perpendicular scattering of the beam electrons. The wider the energy spread and the perpendicular scattering, the stronger the microwave radiation.
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Seiji Miyamoto, Kunioki Mima, Miloš M. Škoric, Moma S. J ...
Subject area: The physics of plasmas and electric discharges.
1998 Volume 67 Issue 4 Pages
1281-1287
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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Temporal pulsations, bursting and incoherence of stimulated Ramanbackscatter in a bounded, underdense plasma were observed inrelativistic particle-in-cell simulations. We show thatbackscatter complexities, modulated and broadened spectra, follow aquasi-periodic and intermittent route toturbulence. We attribute a blue shift to relativistic decrease ofplasma frequency. The bursting follows wave breaking, related to hottail acceleration and bulk heating that further suppress Ramaninstability. Consistency with short-pulse experiments andsimulations at high intensities is outlined.
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Kenichi Nanbu, Kazuki Denpoh
Subject area: The physics of plasmas and electric discharges.
1998 Volume 67 Issue 4 Pages
1288-1290
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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Here is proposed the Monte Carlo collision simulation method for the positive-negative ion recombination whose rate constant is given as a function of temperature. The method makes it possible to simulate a nonequilibrium state of ions in electric discharges.
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Jun Kokubun, Kohtaro Ishida, Vladimir E. Dmitrienko
Subject area: Structure of liquids and solids; crystallography.
1998 Volume 67 Issue 4 Pages
1291-1295
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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Interference between multiple-beam Renninger reflections and “forbidden” reflections, which are excited owing to the anisotropy of X-ray susceptibility of atoms, is considered. It is shown that the tensor structure factors of “forbidden” reflections due to the glide-plane and (or) screw-axis can be completely determined from X-ray data. Both real and imaginary parts of the local polarization anisotropy of atoms can be measured using this method, even in cubic crystals. A detailed calculation is presented for a FeS
2 (pyrite) crystal.
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C. A. Meriles, J. Schneider, L. A. de O. Nunes, A. H. Brunetti
Subject area: Structure of liquids and solids; crystallography.
1998 Volume 67 Issue 4 Pages
1296-1302
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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p-Chloronitrobenzene exhibit an order-disorder phase transition at 282, K. The high temperature disordered phase has P2
1/c symmetry with two molecules per unit cell. A statistically centrosymmetric array results from the superposition of molecules occupying regular lattice sites but facing randomly opposite directions. The ordered low temperature phase structure could not be resolved yet. In the present work, Raman spectroscopy measurements were carried out as a function of temperature in the range 5, K--300, K in ordered and disordered phases of p-chloronitrobenzene. Symmetry information of the ordered unknown phase was obtained. A comparison of experimental results with Raman spectra of p-dihalobenzenes and p-dinitrobenzene has been carried out and possible molecular arrangements are discussed through lattice dynamics calculations.
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Akira Akiba, Hitoshi Yamada, Ryuji Matsuo, Yasushi Kanke, Tetsuji Haei ...
Subject area: Equations of state, phase equilibria, and phase transitions.
1998 Volume 67 Issue 4 Pages
1303-1305
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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The specific heat of NaV
6O
11 single crystal was investigatedwith an AC calorimeter. Lambda type anomalies at 64.3, 80.1 and 242.7 K were observed. It is found that the transition temperature of the P6_3/mmc - P6_3mc structural transition is 242.7 K, which has been reported to occur at a temperature between 200 K and room temperature. The anomalies at 64.3 and 242.7 K coincide well with the two magnetic transitions previously reported. Present specific heat study coupled with single crystal X-ray diffraction data reveals that the P6_3mc - Cmc2_1 structural transition occurs at 80.1 K and accompanies the kink in the resistivity.Previous study reported that the P6_3mc - Cmc2_1 structural transition occurs at 35--40 K, however no anomaly in the specific heat was observed at 35--40 K in this study.
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Yoshihiro Ishibashi
Subject area: Equations of state, phase equilibria, and phase transitions.
1998 Volume 67 Issue 4 Pages
1306-1307
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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The long period commensurate structures are discussed in the framework of discrete atomic models. It is pointed out that usually there are two kinds of atomic displacement patterns in equilibrium in discrete models. A simple but reliable method to guess qualitatively the long period commensurate structures will be proposed.
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Akihito Kikuchi
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1308-1312
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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The electronic structure of LaTe_2 is calculated from the first principles using DV-Xα method.The Fermi surface of this material is mainly contributed from theTe square sheet in the crystal and it has several large parallel piecesthat satisfy the nesting condition for CDW transition.Furthermore, the electronic structure of the LaTeSb, as an example ofantimony doped case, will be presented.From the obtained Fermi surface the behavior of CDWwill be discussed and related to the experimental data.
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Liang–Jian Zou, Zheng Qing–Qi
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1313-1318
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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Effect of level statistics on local electronic states and local magnetism in nanoscale metallic grains with transition-metal impurity in the ballistic regime is studied. It is shown that the mean occupation of local electron and the local magnetic moment in nanoscale metallic grains with odd conduction-electrons are larger than those with even conduction-electrons. The effect of even-odd parity on the condition for the occurrence of local magnetic moment is also discussed, it is found that the critical value, ρ
d(0)U
c, for the formation of local moment in nanoscale metallic grains is much smaller than that in bulks. The dependences of the local spin susceptibility on size and the Coulomb interaction are obtained. These results show that the level statistics plays an important role for the local magnetism, it distinguishes the properties of nanoscale metallic grains from those of clusters and bulks.
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Yasuhiro Saiga, Yoshio Kuramoto
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1319-1331
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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The dynamical properties of the S=1/2 antiferromagnetic XXZ chain are studied by the exact diagonalization and the recursion method of finite systems up to 24 sites.Two types of the exchange interaction are considered: one is the nearest-neighbor type, and the other is the inverse-square one.As the Ising anisotropy becomes larger, there appears a noticeable difference in the transverse component S
xx(q, ω) between the two types of the exchange.For the nearest-neighbor type, the peak frequency of S
xx(q, ω) for each q approaches the center of the continuum spectrum.On the contrary, the peak frequency for the inverse-square type moves to the upper edge of the continuum, and separates from the continuum for the anisotropy larger than the threshold value.Whether the interaction between domain walls (solitons) is absent or repulsive in the Ising limit leads to this difference in the behavior of S
xx(q, ω).In the longitudinal component S
zz(q, ω), on the other hand, the feature of the dynamics is scarcely different between the two types.The energy gap and the static properties are also discussed.
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Tomoki Yoshioka, Yoji Ohashi
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1332-1341
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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We investigate the electronic state around a magnetic impurity in thesuperconductivity in order to clarify how the anisotropy of thes-d interaction works in the presence of the superconductingenergy gap. Using the numerical renormalization group method, weobtain regions induced by the anisotropy where two localizedexcited states with different energies appear at the same time; theycannot obtain as far as the isotropic interaction is considered. Thismeans that the anisotropy of the s-d interaction works relevantlyin some cases in the superconducting state. We also examine whether ornot the bound state energy for the anisotropic and antiferromagnetics-d interaction is scaled by T
K/Δ (T
K: Kondotemperature, Δ: superconducting order parameter), and find thatit does not hold in the regions with two bound states.
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Shingo Tanaka, Hisatomo Harima, Akira Yanase
Subject area: Electron states in condensed matter.
1998 Volume 67 Issue 4 Pages
1342-1351
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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We have performed calculations of Fermi surfaces for cubic Laves-phase heavy fermion compounds CeCo
2, CeRh
2 and CeRu
2, and enhanced electronic specific-heat coefficients γ
ehs (i.e., mass enhancement factor), in which many-body effects are taken into account.The calculated Fermi surfaces of CeCo
2 and CeRu
2 are in good agreement with the dHvA measurements.On the other hand, the results for CeRh
2 hardly show satisfactory explanations for the measurements.Then, we have calculated enhancement factors ˜γ for density of statesof f-electrons using a method of perturbation expansion with respectto electron-electron interactions based on Fermi liquid theory.The values of γ
ehs calculated by using ˜γ reproduce well the experimental values for CeCo
2 and CeRu
2.
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Takashi Harada
Subject area: Electronic transport in condensed matter.
1998 Volume 67 Issue 4 Pages
1352-1358
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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Iron dichalcogenides FeX
2 (X=S, Se and Te) attract interest as semiconducting material containing narrow 3d band. FeS
2 crystallizes in a cubic pyrite-type structure, and both FeSe
2 and FeTe
2 in an orthorhombic marcasite-type one. Electrical resistivity (ρ ), Hall coefficient (R
H) and thermoelectric power (S) were studied on the synthetic samples of iron dichalcogenides FeX
2 (X=S, Se and Te) in the wide temperature range (77, K--600, K). The measurements of ρ, R
H, and S were done for the same sample which is made in the proper preparation condition to get the mutually complementary informations with each other. All the prepared compounds are semiconductive at temperatures from 77, K to 600, K. Energy gaps, E
Gh (ρ ) and E
Gh (R
H), are estimated from the temperature dependence of ρ and R
H in the region at high temperatures. The energy gap was found to decrease systematically from FeS
2 to FeTe
2.
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Hiroshi Shimada, Keiji Ono, Youiti Ootuka
Subject area: Electronic transport in condensed matter.
1998 Volume 67 Issue 4 Pages
1359-1370
Published: April 01, 1998
Released on J-STAGE: October 01, 1999
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The mechanism of the magneto-Coulomb oscillation in ferromagnetic single electron transistors (SET's) is theoretically considered. Variations in the chemical potentials of the conduction electrons in the ferromagnetic island electrode and the ferromagnetic lead electrodes in magnetic fields cause changes in the free energy of the island electrode of the SET. This is a plausible origin of the conductance oscillation of the SET in sweeping an applied magnetic field.
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