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Biswanath Rath
Subject area: Mathematical methods in physics.
1997 Volume 66 Issue 12 Pages
3693-3695
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A systematic procedure for constructing a convergent perturbation theoryis developed.This procedure can be used to calculate energy levels as well as wavefunctions. Asan example of this, it has been applied to an anharmonicoscillator ground state with a strong coupling limit as well as a weakcoupling limit.
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Sergei Bulanov, Enzo Lazzaro, Jun–ichi Sakai
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3696-3699
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We present results of the classical and quantum descriptions of the chargedparticle motion near aneutral surface of a magnetic field, where the magnetic field vanishes. Farfrom the neutral surface, the drift approximation is valid within the classical limit whereas theLandau description of thecharged particle in the magnetic field can be used in the quantum case. Inthe vicinity of theneutral surface, at the distance in the classical regime less than theLarmor radius, the particlemotion is nonadiabatic. Here the motion of the particle is described by theSchrödinger equation withthe potential that corresponds to that of the harmonic oscillator withfrequency that dependent onthe particle momentum along the neutral surface.
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Kenji Hiraga, Tetsu Ohsuna, Kazumasa Sugiyama
Subject area: Structure of liquids and solids; crystallography.
1997 Volume 66 Issue 12 Pages
3700-3702
Published: December 01, 1997
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We propose an atom cluster model of F-type icosahedral quasicrystals based on the structure of an α -(AlPdMnSi) phase, which is a p/q=1/1 cubic approximant of icosahedral quasicrystals. In the model, large dodecahedral and small icosahedral atom clusters, which are located at the (1/2, , 1/2, , 1/2) and (0, , 0, , 0) positions in the α -(AlPdMnSi) structure, respectively, are placed at twelvefold sites classified into two groups in the three-dimensional Penrose lattice. A diffraction pattern of this model reproduces well the characteristic features of an electron diffraction pattern of the F-type Al--Pd--Mn icosahedral quasicrystal.
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Hiroyuki Fujishiro, Manabu Ikebe, Yoshiyuki Konno, Tetsuo Fukase
Subject area: Mechanical and acoustical properties of condesed matter.
1997 Volume 66 Issue 12 Pages
3703-3705
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The sound velocity v
s(T) and the electrical resistivity ρ (T) of La
1-XSr
XMnO
3 (0.11≤ X≤ 0.17) have been measured and anomalies in v
s(T), which are related to the polaron-ordered phase centered at X=1/8, have been observed. The phase diagram between the polaron-ordering temperature T
P and X has been determined from the v
s anomalies.
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Masanori Ogura, Hiroshi Namaizawa
Subject area: Quantum fuids and solids: liquid and solid helium.
1997 Volume 66 Issue 12 Pages
3706-3709
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Stimulated by recent experiments on the heat capacity of ^3He adsorbed on ^4Heprecoated Hectorite we shall study the thermodynamics of strongly interactingfermions in two-dimension (2D) at low temperatures.We shall focus on spin fluctuations (SF) and resort to the random phase approximation (RPA)to obtain the thermodynamic potential. To take full account of the degree of freedom of SF, integrals including the RPAsusceptibility are calculated numerically over the effectively entire energy-momentum space without imposing the conventional paramagnon approximation or the like. In addition to the T-linear term, we have found that the heat capacity as well as the entropy develop T^2-terms at verylow temperatures for T ≤ T
* and T log T-termswhich take over the former for T ≥q T
*, where T
* is the crossover temperature defined numerically.We have compared our results for heat capacity with those obtained experimentallyand, as a first finding, located Tlog T-term as predicted. Secondly, in the frame work of Stoner-Hubbard or Landau's Fermi liquid theory, we have proposed and carried out a method of analysis of the data to evaluatethe parameters of both theories.
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Takeo Hoshi, Takeo Fujiwara
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3710-3713
Published: December 01, 1997
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We construct a fully-selfconsistent formalismof ab initio electronic-structure calculations, where basis orbitals are localized, nonorthogonal, andgiven on a real-space regular grid.A window function is adoptedto optimize localized basis orbitals.As an example, the ground state of diamond crystal is calculatedusing the ultrasoft pseudopotential.
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Hiroaki Ikeda, Kazumasa Miyake
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3714-3717
Published: December 01, 1997
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Fermi liquid description of heavy Fermions withthe f
0-f
1-f
2 configuration is studied by using the slave boson technique.In particular, it is shown that a new type of Fermi liquid state is realized in the case where the f
2 configuration with a singlet crystal field groundstate is predominant. Namely, the quasiparticle contribution χ
qp to the magnetic susceptibility is not enhanced while the density of states of quasiparticle is enhanced producing the heavy Fermions. A relevance to an anomalously small reduction of the Knight shift across the superconducting transition observed in UPt
3 is discussed.
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Mamoru Sakaue, Hideaki Kasai, Ayao Okiji
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1997 Volume 66 Issue 12 Pages
3718-3721
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A simple model is introduced to investigate the temporal evolution of the density of electrons which are excited from a metal substrate to a localized state at the surface by a laser pulse. The electron system consists of two subbands in the substrate and a localized state at the surface, and the localized state is in resonance with the upper subband. The obtained expression for the electron density in the localized state indicates that the excitation process can be divided into two, i.e., direct and indirect processes. In the latter, the transition probability reaches a maximum at a certain photon energy (absorption peak energy /) because of the momentum conservation. This process contributes substantially to the electron density and hence strongly affects its temporal evolution at the incident photon energy around the absorption peak energy.
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Ryuta Yagi, Shun–ichi Kobayashi, Youiti Ootuka
Subject area: Superconductivity.
1997 Volume 66 Issue 12 Pages
3722-3724
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We studied the effect of the energy dissipation in single small Josephson junctions by attaching external shunt resistors. We observed a superconductor-insulator (S-I) transition driven by the shunt resistor. We determined the phase diagram for the S-I transition experimentally.
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JunIchiro Kishine, Kenji Yonemitsu
Subject area: Superconductivity.
1997 Volume 66 Issue 12 Pages
3725-3728
Published: December 01, 1997
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Effects of the interladder one-particle hopping, t
⊥, on the low-energy asymptotics of a weakly coupled Hubbard ladder system have been studied, based on the perturbative renormalization-group approach.We found that for finite intraladder Hubbard repulsion, U, thereexists a crossover value of the interladder one-particle hopping, t
⊥ c.For 0
⊥⊥ c, the spin gap metal (SGM) phase of theisolated ladder transits at a finite transition temperature, Tc, to the d-wave superconducting (SCd) phase via a two-particle crossover.In the temperature region, Tc, interladder coherent Josephson tunneling of the Cooper pairs occurs, while the interladder coherent one-particle process is strongly suppressed.For t⊥ c⊥, around a crossover temperature, Tcross, the system crosses over to the two-dimensional (2D)phase via a one-particle crossover. In the temperature region, Tcross, the interladder coherent band motion occurs.
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Hiroshi Matsui, Akira Ochiai, Hisatomo Harima, Hidekazu Aoki, Takashi ...
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1997 Volume 66 Issue 12 Pages
3729-3732
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We report on the cyclotron resonance (CR) measurements performed on Yb_4As_3 using the cavity perturbation (TE
101 and TE
102) and simple transmission techniques without a cavity for microwaves (16--110 GHz) at 22 ≥q T ≥q 0.55 K and H ≤ 10 T. CR and electron spin resonance (ESR) have identified each other by the systematic comparison of the data obtained from the three different measurement techniques performed. The CR that is symmetric and strongly temperature-dependent has a CR mass of 0.72m_0, while the ESR which is rather antisymmetric and very weakly temperature-dependent, has g=2.04. The comparison of the CR mass with the recent band structure calculations based on the LAPW method concludes that the observed CR is caused by the light 4p-holes of As ions centered at the Γ point, the band mass of which is calculated to be about 0.7m_0. We discuss the temperature dependence of the electron relaxation time obtained by the linewidth analysis performed for the CR.
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Yasusada Yamada, Shinichiro Nohdo, Naoshi Ikeda
Subject area: Dielectric properties and materials.
1997 Volume 66 Issue 12 Pages
3733-3736
Published: December 01, 1997
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The charge ordering process of a mixed valence LuFe
2O
4 system has been studied, focusing attention on the frustration effect associated with the charge configuration. It is revealed that the system undergoes successive phase transitions following the sequence of disorder→ 2D CDW→ 3D CDW. In the 2D-CDW state, the charge density wave defined by the wave vector (1/3, , 1/3), is formed in the hexagonal layer. On the nodal lines of the CDW, the charge order is still undetermined due to the charge frustration. From a dielectric viewpoint, this phase is viewed as random stacking of 2D ferroelectric layers. In the 3D-CDW state, antiphase stacking of the 2D ordered layer develops. At the same time, the in-plane charge order exhibits a doubly modulated long-period structure. From a dielectric viewpoint, this phase is characterized by an incommensurate antiferroelectric phase. Relevance of the charge ordering mechanism to the observed anomalously large dielectric constant in LuFe
2O
4 is discussed.
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Yutaka Toyozawa
Subject area: Biophysics.
1997 Volume 66 Issue 12 Pages
3737-3740
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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On the basis of the thermodynamic argument of the characteristic feature distinguishing the living world from the nonliving, it is postulated that the radiation from the sun created living organisms on the earth and has been their constant driving force. In view of the fact that the basic biomolecules have chemical energies of several or more electron volts, significantly higher than the average energy of a photon from the sun, we propose a mechanism of multistep photoexcitations of inorganic material for the photosynthesis of these metastable molecules which would not exist at ambient temperature. The preference of the photoexcitation against the radiative and nonradiative de-excitation is ascribed to the suppression of the latter by rapid and large relaxations (reactions) in intermediate states. An experiment to confirm the mechanism is proposed in which geological time is reduced to an accessible one.
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Hideyuki Mizuta, Miki Wadati
Subject area: Mathematical methods in physics.
1997 Volume 66 Issue 12 Pages
3741-3750
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Thermodynamic quantities of solvable models such as one--dimensionalHeisenberg model can be obtained through the Finite temperature Baxterformula. For the low--temperature expansions, the estimate of the finitesize corrections by use of the Euler--Maclaurin formula is essential.There has been a question on the convergence of such calculations.In this paper, we confirm that the Euler--Maclaurin formula gives the correctlow--temperature expansion of the free energy for the XXZ Heisenberg model.
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Norio Konno
Subject area: Mathematical methods in physics.
1997 Volume 66 Issue 12 Pages
3751-3755
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Upper bounds on survival probabilities of a nonattractive model are obtained by using a modified version of the Harris lemma.
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Kazuhiro Hikami, Kiyoshi Sogo, Rei Inoue
Subject area: Mathematical methods in physics.
1997 Volume 66 Issue 12 Pages
3756-3763
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We reveal the hidden algebraic symmetry of the Bogoyavlensky lattice(the extended Volterra model).Shown is the correspondence betweenthe lattice W algebra and the Bogoyavlensky lattice.Soliton solutions are also constructed in terms of the vertex operators.
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Alex Yu. Tretyakov, Norio Inui, Norio Konno
Subject area: Statistical physics and thermodynamics.
1997 Volume 66 Issue 12 Pages
3764-3769
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Numerical estimates of criticalvalue and critical exponent for the one-sided contact process inone dimension are obtained by using Monte Carlo simulation andpower series expansion techniques. Moreover we give rigorous boundson its critical value.
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Yasuhiro Fujii, Miki Wadati
Subject area: Statistical physics and thermodynamics.
1997 Volume 66 Issue 12 Pages
3770-3777
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We study reaction-diffusion processes with multi-species of particles on a hypercubic lattice. We define the particle density operators for multi-species case and express the time evolution equation of correlation functions in quantum Hamiltonian formalism. We consider the conditions that the time evolution of correlation functions does not generate higher-order correlation functions. These conditions are called the closed conditions. Moreover we generalize the dual processes which are known in the symmetric exclusion processes and find that the Hamiltonian of the dual processes fixes the time evolution of correlation functions of processes with multi-species of particles.
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Tomohide Nakamura, Ichita Endo, Atsushi Fukumi, Takayoshi Horiguchi, Y ...
Subject area: Atomic spectra and interactions of atoms with photons.
1997 Volume 66 Issue 12 Pages
3778-3782
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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By means of the atomic-beam laser spectroscopy, the Zeeman effects of the transitions 4f
13(
2F
o)6s
2 0 cm
-1 → 4f
13(^{2]F
o7/2)6s6p(
3P
o0) 16742.237 cm
-1, 4f
13(
2F
o7/2)6s6p(^3P
o1) 17343.374 cm
-1 in Tm I are systematically investigated by applying the magnetic field up to 250 gauss. From the analysis, the magnetic dipole constants A for the three levels have been determinedto be -374.40(35), -737.53(45), -166.56(14) MHz, respectively. The precise g-factors of the upper levels have been determined to be 1.31954(16), 1.02154(10), respectively. The theoretical Zeeman splittings calculated using these values are found to reproduce experimental data well.
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Appathurai N. Perumal, Deep N. Tripathi
Subject area: Atomic and molecular collision processes and interactions.
1997 Volume 66 Issue 12 Pages
3783-3789
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The classical trajectory Monte Carlo simulation has been used to investigate the collisions of protons with alkali metal atoms in their ground state. Model interaction potential has been used to describe the electron-ionic core interaction. The cross sections for the capture and ionization in the energy range 1--100, keV/amu have been calculated and compared with the available experimental and theoretical results. The effects of the presence of a strong static electric field in different geometrical features on the capture and ionrzation cross sections have also been investigated. It has been found that the electric field causes the cross section for the capture to decrease while for the ionization enhance dramatically. Many of the null field features are retained. The analyses of the final state n, , l-distribution in the electron capture process reveals H(2p) to be the most populated level in both the cases, with and without electric field.
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Hirofumi Watanabe, Frederick John Currell, Hiroyuki Kano, Nobuo Kobaya ...
Subject area: Atomic and molecular collision processes and interactions.
1997 Volume 66 Issue 12 Pages
3790-3794
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Single and double electron capture processes by O
6+ from He at 90, keV have been investigated by observation of the emission spectrum in the wavelength region of 290--510, nm. In addition to transitions from excited states of O
5+ populated by single electron capture processes, Yrast transitions from Rydberg states (1s
22snl) of O
4+ populated by double electron capture have been observed. Transfer target excitation processes have been confirmed by the observation of transitions from excited states of He
+.
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Hirofumi Watanabe, Junji Asada, Frederick John Currell, Tsunemitsu Fu ...
Subject area: Experimentally derived information on atoms and molecules: instrumentation and techniques.
1997 Volume 66 Issue 12 Pages
3795-3800
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We have constructed a new Electron Beam Ion Trap (EBIT). Over recent months, we have operated this device and obtained some experimental results. In this paper, we show the performance of this EBIT by illustrating these results.
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Makoto Okamura
Subject area: Fluid dynamics.
1997 Volume 66 Issue 12 Pages
3801-3808
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Resonant standing waves on finite depth water are obtained analytically andnumerically. The analytical solutions are determined to fifth orderwhich is the minimum order to investigate harmonic resonance.Three different wave profiles are obtained for a given parameter ofA
11, where A
11 is an expansion coefficient of the fundamental mode.We have found an interesting fact that the depth dependence of one ofthe fourth order coefficients is qualitatively different fromthat of the other coefficients for relatively deep water.We have furthermore obtained the analytical solution which explains the fact.A new method to calculatestanding waves of large amplitude on finite depth water is also presented.
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Teruo Saito, Yoshinori Tatematsu, Yasuhito Kiwamoto, Hidetoshi Miyaue, ...
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3809-3814
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Temperature of end loss electrons is a base factor in data analysis of an axial potential profile and electron transport in an end region of a tandem mirror. In this analysis, a large ratio of a magnetic field strength at a mirror throat to that at an end wall, where the end loss electron temperature is measured, may bring an error in evaluation of the end loss electron temperature. In addition, anisotropy of the electron velocity distribution is also a source of error. By using a bi-Maxwellian velocity distribution of end loss electrons as a test function, relation between the measured electron temperature and the parallel electron temperature at the mirror throat is given as a function of the temperature anisotropy. Then, theoretical predictions from a potential model of the axial potential distribution and the electron transport are expressed by using the measured electron temperature. The present analysis shows that, when the measured temperature is fixed, the potential difference along a magnetic field line and the electron transport are maximum for a nearly isotropic velocity distribution.
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Nobuhiko Hayashi, Tomonori Takizuka, Akiyoshi Hatayama, Masatada Ogasa ...
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3815-3825
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A five-point model for the scrape-off layer and divertor plasmas has been developed to study the inside/outside divertor asymmetry induced by the divertor biasing. Effects of divertor biasing on the asymmetry are studied for low and high recycling states. In the low recycling, the biasing has a little influence on the asymmetry. On the other hand, in the high recycling, the biasing substantially controls the asymmetry. The divertor plasma has higher density and lower temperature at the anode-side plate compared with those at the cathode-side plate.
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Hisanori Takamaru, Tetsuya Sato, Ritoku Horiuchi, Kunihiko Watanabe, ...
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3826-3830
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A boundary-free particle simulation model, applicable to a local open system in which the internal plasma is continuously and smoothly connected to an external plasma source such as a current generator, is developed. We present this formalism and examine the range of applicability of this procedure. This scheme assures a balance between the outgoing and incoming particle fluxes through the system boundaries at each time step. The numerical code developed on this principle is applied to an ion acoustic double layer under the condition that the system is connected to a constant current generator to confirm the soundness and validity of the code.
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Jerome L. V. Lewandowski
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3831-3841
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A 4-field model describing collisional drift waves in arbitrary3-dimensional plasma geometry is derived. Linear growth ratesfor the perturbed plasma density, electrostatic potential, parallelion velocity and electron temperature are obtainedby solving the 4-field model as an initial-value problem.The local attributes of the confining magnetic fieldare retained exactly.Numerical solution for toroidal heliac H1-NF is presented.It is shown that the collisional drift wave can be drivenunstable and that the spatial structure of the mode isstrongly ballooning in character.
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Shinji Yoshimura, Yoshiharu Nakamura, Tsuguhiro Watanabe, Yoshinobu Ka ...
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3842-3846
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Excitation and propagation of ion waves in a negative ion plasma are investigated numerically and compared with the experiments which have been performed using Q-machine and multidipole dc discharge device. The dispersion relation of the ion waves derived from conventional complex ω-plain procedure cannot explain previously observed simultaneous propagation of the fast and the slow mode. Spatial excitation coefficients of the slow mode, which are calculated from complex k /-plain procedure, are comparable to that of the fast mode. Furthermore, if there exists a plasma ion flow which decreases damping of both modes, the spatial excitation coefficients of the slow mode will increase. From this point of view, the simultaneous propagation of both modes may be possible under a certain laboratory condition. Also the direct calculation of wave potential is presented. In the region not too close to the excitation point, the principal mode which propagates in a negative ion plasma is found to be the fast mode. In the case where T_+=T
e and there is a finite ion flow, the interference pattern between the fast and the slow mode appears in the vicinity of the excitation point. Finally, we compare the results with laboratory experiments. Our numerical calculations qualitatively explain the previous observations of the slow mode.
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Ryo Sugihara, Hideyasu Shamoto
Subject area: The physics of plasmas and electric discharges.
1997 Volume 66 Issue 12 Pages
3847-3853
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Properties of a laser beam propagating perpendicular to the external magnetic field in a plasma are investigated theoretically. The beam is represented by a Helmholtz equation in almost all plasma parameter space. For the upper hybrid wave region the wave equation turns to a hyperbolic partial differential equation. It is shown that both equations can be exactly solved by using a method of separation of variables and that solutions having Gaussian profiles lateral to the propagation direction are obtained. An appreciable difference between two solutions appears in their phase factors. Owing to the asymmetry of the configuration around the axis of wave propagation the cross sections of beams take shapes of ellipse and each beam has two different focus points.
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Mitsuaki Ginoza, Makoto Yasutomi
Subject area: Structure of liquids and solids; crystallography.
1997 Volume 66 Issue 12 Pages
3854-3858
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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In a solution containing microions from an added electrolyte, the effective interaction potential between colloidal particles is studied on the basis of the primitive model. The approximation is employed that the correlations of solvent-particles with microions can be neglected, and the potential is calculated with the use of the mean spherical approximation solution of the Ornstein-Zernike equation with the Yukawa closure. In the case of the hydrophobic colloid, the theory is discussed in comparison with the DLVO theory and a role of the solvent-mediated potential is emphasized.
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Fujio Kakinuma, Yoshimi Tsuchiya, Kenji Suzuki
Subject area: Thermal properties of condensed matter.
1997 Volume 66 Issue 12 Pages
3859-3863
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Sound velocity and density measurements have been made to investigate the thermodynamic properties of the liquid Sn--Se system. The molar volume and adiabatic compressibility have been deduced as a function of temperature and composition which show large negative deviation from the ideal behaviour. The results indicate that two kinds of chemical ordering, one around 50, at.\latter becomes unstable with raising temperature to cause apparently complex behaviour of the thermodynamic functions.
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Tadao Kasuya, Seiichi Itabashi
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3864-3875
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Magnetoelastic effects measured previously on Ce
xLa
1-xB
6 were reanalyzed based on the dynamical Jahn-Teller effect as a single site effect and the paired distortion as an interaction effect developed in recent papers for RB
6 in general. In the dilute systems, we observe an anomalous Curie-Weiss term caused from competition between the single site effect and the pair effect, while in the dense systems anomalies due to pair formation are observed even in the paramagnetic region. Strong frustration inherent to the pair ordering plays an important role. Anomalous properties in PrB
6 and NdB
6 were also interpreted based on the above common model in good agreement with the experimental results, in particular with anomalous neutron scattering measurement. Magnetoelastic effects were measured also on PrB
6 and NdB
6. In PrB
6 the effect is 100 time stronger than that in CeB
6 due to induced mixing through distortions between the nearly degenerated ground levels, Γ
1 and Γ
5. The charge dipolar ordering was also observed clearly at the lower ordering temperature T
2, forcing an incommensurate magnetic ordering to commensurate.
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Tomo Munehisa, Yasuko Munehisa
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3876-3880
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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An extended Hubbard model on a two-leg ladder is numerically studied by means of the quantum Monte Carlo techniques. The model we study has the nearest-neighbor interactions whichare repulsive along chains and attractive for rungs.The plots of the doping parameter versus the chemical potential show two cliff-like regions and a large plateau region.Results on the charge susceptibility suggest it diverges in these cliff-like regions. These observations might imply a signal to the phase separation, which should be related to the effective attractive interactions along chains.
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Shugo Suzuki, Kenji Nakao
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3881-3886
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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A full-potential linear-combination-of-atomic-orbitals method based onthe density-functional theory developed in the field of the molecularscience is extended to the density-functional calculations ofsolids. It is shown that the method is also useful for studying both thestructural and electronic properties of solids. The interatomicdistances of graphite and hexagonal boron nitride are calculatedwithin the error of less than 1%. Also, the atomization energies and the elastic constants are properly reproduced by the present method.
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Takashi Nakayama, Masato Ishikawa
Subject area: Electron states in condensed matter.
1997 Volume 66 Issue 12 Pages
3887-3892
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The bonding, electronic structures and dielectric functions of vacancy-ordered orthorhombic and monoclinic Ga
2Se
3 are calculated by using the ab initio pseudopotential method and the linear response theory. We have found that in these compounds the bonds around vacancies relax such that the bond length fulfills the order as sp
2-like bond ≥q sp-like bond, and the dangling-bond states of anion atoms located nearest to such vacant sites appear at the valence-band top. These states produce the bonding, i.e. one-dimensional band, along the vacancy-ordering direction and become the origin of large optical anisotropy at the absorption edge. The present results well explain the recent experiments.
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Makoto Izumi, Kazuyuki Nakazawa, Yoshichika Bando, Yasuhiro Yoneda, Hi ...
Subject area: Electronic transport in condensed matter.
1997 Volume 66 Issue 12 Pages
3893-3900
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Magnetotransport properties of an 80, nm-thick high quality epitaxial film of SrRuO
3 grown on SrTiO
3(001) were investigated. The film has tetragonal structural symmetry (c-axis ⊥ film plane), and shows a uniaxial strong magnetic anisotropy with the easy axis along the c-axis. Magnetotransport phenomena are also uniaxially anisotropic. Magnetoresistivity, Δρ
xx(H), in longitudinal geometry is negative and becomes larger at T
C. The Hall resistivity, ρ
xy(H), is not proportional to magnetic field because it contains the extraordinary Hall resistivity component, which is composed of negative skew scattering and positive side-jump scattering, both of which are due to spin-orbital interaction. The field-dependence of ρ
xy(H) indicates that the origin of Δρ
xx(H) of SrRuO
3 is the spin-dependent scattering. The ordinary Hall coefficient depends on temperature in such a way that, among multi carriers electron type carriers become dominant below T
C.
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Yuri P. Monarkha, Kimitoshi Kono
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1997 Volume 66 Issue 12 Pages
3901-3907
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We present the theory of transport properties and vibration modes of the two-dimensional Wigner solid (WS) coupled to surface dimples on normal and superfluid
3He. Compared to the case of liquid
4He, Fermi liquid properties of the substrate crucially affect the low-frequency dynamics of the electron solid. At ultralow temperatures, WS transport is shown to be determined mostly by the reflection of ballistic quasiparticles of the bulk liquid at the dimple sublattice. The long mean free path regime of normal
3He is characterized by the temperature-independent conductivity. Below the superfluid transition, the appearance of the quasiparticle energy gap sharply reduces the momentum adsorbed by moving dimples, which leads to the rapid increase of the WS conductivity. The analysis presented shows that the WS can serve as a new powerful experimental probe for superfluid phases of
3He.
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Takeshi Inaoka
Subject area: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1997 Volume 66 Issue 12 Pages
3908-3921
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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In a broad size range, we examine how dipolar surface plasmons in spherical small particles are composed of their constituent electronic transition processes. A series of transition processes satisfying specific selection rules are found to play the leading part in formation of the surface-plasmon mode. As the number of these leading transition processes becomes larger with increase in size, the mode assumes more collective-excitation character, and evolves into a more complete surface excitation having its induced charges more sharply localized around the surface. Our decomposing analysis shows how the above transition processes create a surface excitation and yield the giant resonance in a photoabsorption spectrum.
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Chong Der Hu
Subject area: Superconductivity.
1997 Volume 66 Issue 12 Pages
3922-3927
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We studied the ac Josephson effect. In the resistively shunted junction model (RSJ) the phase difference is expanded in Fourier series. The Fourier components can be evaluated by solving the equations of motion. Truncation is applied to deal with the infinite products and series of Bessel functions. We calculate the constant-voltage steps and find that they are complicate functions of the ac power input.
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Masanori Ichioka, Naoki Enomoto, Kazushige Machida
Subject area: Superconductivity.
1997 Volume 66 Issue 12 Pages
3928-3943
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The vortex lattice structure in a d
x2-y2-wave superconductor is investigated near the upper critical magnetic field in the framework of the Ginzburg Landau theory extended by including the correction terms such as the higher order derivatives derived from the Gor'kov equation. On lowering temperature, the unit cell shape of the vortex lattice gradually varies from a regular triangular lattice to a square lattice through the shape of an isosceles triangle. As for the orientation of the vortex lattice, the base of an isosceles triangle is along the a axis or the b axis of the crystal. The fourfold symmetric structure around a vortex core is also studied in the vortex lattice case. It is noted that these characteristic features appear even in the case the induced s-wave order parameter is absent around the vortex of the d
x2-y2-wave superconductivity. We also investigate the effect of the induced s-wave order parameter. It enhances (suppresses) these characteristic features of the d
x2-y2-wave superconductor when the s-wave component of the interaction is attractive (repulsive).
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Atsuhiro Kitazawa, Kiyohide Nomura
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3944-3956
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Critical properties of the spin-1 bond-alternating XXZ chain are studied numerically. This model is appropriate to study the VBS picture and hidden Z
2× Z
2 symmetry concerning to the Haldane gap problem. The possible phases are the ferromagnetic, the XY, the Haldane, the dimer, and the Néel ones. The critical properties of this model can be interpreted as theAshkin-Teller type reflecting the hidden Z
2× Z
2 symmetry. The phase transitions are of the Berezinskii-Kosterlitz-Thouless type (XY-Haldane and XY-dimer), of the 2D Gaussian type (Haldane-dimer), and of the 2D Ising type (Haldane-Néel and dimer-Néel). We determine the phase boundary and universality class using the recent developed techniques by the authors.
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Masafumi Sera
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3957-3961
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The elastic constants C_Γ in the antiferro-quadrupole (AFQ) ordered state with two sublattices were studied by a mean field approximation. The temperature dependence of C_Γ below the AFQ ordering temperature T
Q in the zero magnetic field depends on the type of the AFQ order parameter and the applied strain. They are in principle the same as those of the parallel and perpendicular magnetic susceptibilities in the antiferromagnetic state. The magnetic field dependences of C_Γ also show the characteristic behaviors depending on the type of the AFQ ordering and the applied strain. We discuss C_Γ of CeB
6 which shows the AFQ ordering at T
Q=3.3, K by comparing the calculated results.
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Hideo Yoshioka, Yoshikazu Suzumura
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3962-3969
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We examine spin-Peierls states in the presence of spin defects for CuGeO_{3 where magnetic ions Cu
2+ are replaced by non-magnetic ones Zn
2+. Based on the action for the bosonized Hamiltonian, the state is investigated by using path integral method. The temperature of spin-Peierls transition T
SP and, the spin gap and the magnitude of the averaged lattice dimerization in the ground state have been calculated as a function of doping. From comparison of the present T
SP with the experimental result, a good agreement is obtained for the transition temperature of Cu
1-δ Zn_δ Ge O_3 in the region of the doping rate, δ <0.02.
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Toshio Mizushima, Yosikazu Isikawa, Junji Sakurai, Masayoshi Ohashi, Y ...
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3970-3974
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Neutron powder-diffraction measurements ofPrNiAl_4 were carried out at temperaturesabove and below the Néel temperature of 8.4 K.The antiferromagnetic structurewas determined; the propagation vector is (010), andthe magnetic moment is 2.59μ
B along the a-axis.This magnetic structure is consistent with the results ofmagnetization and magnetic susceptibility measurementson a single crystalline sample.
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Hisashi Sasaki, Hiroshi Harashina, Katsuaki Kodama, Shinichi Shamoto, ...
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3975-3980
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Dynamical magnetic properties of BaCoS
2 which has a layered structure and exhibits Mott metal-insulator (M-I) transition with the Ni-substitution for Co and/or with increasing external pressure p, have been studied by means of neutron inelastic scattering in the pressure range of 0{\less--}p{\less--}15 kbar. By comparing the results with those of BaCo
0.82Ni
0.18S
2, we find that characteristics of the magnetic fluctuations near the two M-I transitions induced by pressure and by the Ni-substitution for Co are rather different, even when they are compared under the conditions of similar Néel temperatures and similar antiferromagnetic staggered moments at low temperatures.
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Yuuki Watanabe, Seiji Miyashita
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3981-3987
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We investigate magnetic properties in the ground state of the one-dimensional flat-band Hubbard model in high electron filling. Until now, we found the new saturated ferromagnetism for odd numbers of holes, and its properties were investigated in detail. However, it was remained as a problem how we understand the complete alternation of magnetism between saturated ferromagnetism and singlet for odd and even numbers of holes, respectively. This alternation causes a difficulty when we consider the thermodynamic limit. In order to solve this difficulty, we investigate, at first, the change of the magnetization for systems with various boundary conditions, and we find that even for the even numbers of holes, the ground states are saturated ferromagnetic under the antiperiodic boundary condition. Furthermore, we explicitly investigate the spin-spin correlation functions ‹ S
zi, S
zi › to see the spin ordering. These calculations shows that all ground states in this filling region are the spiral state under a suitable boundary condition, and that the singlet states in these ground states, therefore, have a ferromagnetic order within, approximately, a half of the system size, although the total spin is still zero. From these results, we conclude that the properties in this region are by no means ill, and all ground states are essentially ferromagnetic in the sense that the spins in the singlet states are also ordered ferromagnetically if we take in the half of the system size.
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Dai Aoki, Yasuhisa Katayama, Rikio Settai, Yoshihiko Inada, Yoshichika ...
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3988-3995
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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We have measured the de Haas-van Alphen effect of PrPb_3 whose antiferroquadrupolar ordering occurs at 0.4, K.Main Fermi surfaces consist of four closed ones, which are almost spherical. These Fermi surfaces are the same as those of a non-f / reference compound LaPb_3 in topology, although the cyclotron effective masses are 2 to 6 times larger than those of LaPb_3. The cyclotron effective masses are temperature-dependent, which starts gradually with decreasing the temperature below 1, K. A metamagnetic transition is also found to occur at about 70, kOe below 0.6, K through the magnetization, magnetostriction and AC susceptibility measurements. These phenomena are closely related to the antiferroquadrupolar ordering at 0.4, K.
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Hiroshi Kageyama, Kazuyoshi Yoshimura, Koji Kosuge, Masaki Azuma, Miki ...
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
3996-4000
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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Magnetic properties of Ca
3Co
2O
6 with ferromagnetic Ising chains have been studied using oriented sample along the chain direction. From the extremely anisotropic behavior in its magnetization at low temperatures and in the temperature dependence of magnetic susceptibility, it is suggested that an octahedral Co
3+ is nonmagnetic, whereas a trigonal prismatic Co
3+ has a fictitious spin S'=1 with large single-ion anisotropy (D-- -25, K, , g
//-- 4). At low temperatures below 5, K, multisteps are observed in the magnetization, suggesting the existence of various magnetic structures. The pulsed magnetization measurements reveal that the response of ferromagnetic chains to the field is slow and varies as a function of temperature and ΔH/Δt.
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Kenro Kawano, Minoru Takahashi
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
4001-4008
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The antiferromagnetic Heisenberg spin systems on the three-leg ladder are investigated. Periodic boundary condition is imposed in the rung direction. The system has an excitation gap for allantiferromagnetic inter-chain coupling (J
⊥>0). The estimated gap for the strong coupling limit (J
⊥/J
1 → ∞) is 0.28J
1. Although the interaction is homogeneous and only nearest-neighbor, the ground states of the system are dimerized and break the translationalsymmetry in the thermodynamic limit.Introducing the next-nearest neighbor coupling (J
2), we can see that the system is solved exactly. The ground state wave function is completelydimer-ordered.Using density matrix renomalization group algorithm, we show numericallythat the original model (J
2=0) has the same nature with the exactlysolvable model. The ground state properties of the ladder with a higher odd number of legs are also discussed.
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Kazuyuki Matsuhira, Toshiro Sakakibara, Hiroshi Amitsuka, Giyuu Kido
Subject area: Magnetic properties and materials.
1997 Volume 66 Issue 12 Pages
4009-4016
Published: December 01, 1997
Released on J-STAGE: October 01, 1999
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The measurement of magnetic susceptibility χ (T), specific heat C(T), electrical resistivity ρ (T) and high field magnetization M(H) have been performed on dilute Ce compounds Ce
1-x(La
0.63Y
0.37)
xRu
2Si
2, in which the lattice parameters are made independent of x to avoid the chemical pressure effect. Non-Fermi-liquid like behavior characterized by nearly logarithmic divergence of χ (T) down to -- 200, mK has been observed as x→ 1, which is quite unexpected for the Kondo temperature T
K-- 24, K of CeRu
2Si
2. We show that the characteristic behavior of the experimental results is well reproduced by an impurity Kondo model with a wide distribution in T
K (“Kondo disorder”). A simple model for the T
K distribution is given. In the present dilute alloys, T
K strongly depends on the local environment of nearest-neighbor distance.
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