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Jian–Zhong Ma
専門分野: Mathematical methods in physics.
1995 年 64 巻 11 号 p.
4059-4063
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The relationship between level statistics and the correlation hole inthe survival probability function in generic chaotic systems isinvestigated. It is shown that the depth and the area of the holemeasure the long- and short-range correlations of levels, respectively. Two models of level statistics, namely the Gaudin modeland an independent superposition of circular unitary ensembles, areanalyzed as examples for systems intermediate between chaos andintegrability.
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Hideaki Ujino, Miki Wadati
専門分野: Mathematical methods in physics.
1995 年 64 巻 11 号 p.
4064-4068
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Following the definition of Haldane's exclusion statistics, we proposea new and simple representation of the spectrum and the state countingof the quantum Calogero model. We show that N non-interactingparticles with statistical interactions confined in an externalharmonic well give exactly the same energy spectrum and the samedegeneracy as those of the N-particle quantum Calogero model. We alsoshow that this picture exactly corresponds to the generalized idealgas, which was introduced by Bernard and Wu.
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Alex Yu. Tretyakov, Norio Konno
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 11 号 p.
4069-4072
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Numerical estimates of critical value and critical exponents for thecontact process on the binary tree are given.
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Hitoshi Hojo, Yasuaki Kishimoto, James W. Van Dam
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4073-4076
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The Kelvin-Helmholtz mode instability driven by an equilibrium radialelectric field in a cold plasma is studied analytically for flute-typeperturbation in cylindrical geometry. The growth rate and a thresholdin the radial gradient scale length of the E× B drift frequencyfor instability are obtained.
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Mika Urano, Yasunori Ohkuma, Tsutomu Takahashi, Kiyomitsu Suzuki, Yasu ...
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4077-4080
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Near-infrared radiation from a field-reversed-configuration (FRC)plasma is observed during the stable phase using optical fibertubes. Internal structure of the FRC is estimated from an Abelinversion of the radiation intensities which are obtained from thevertical array of the fibers. It is confirmed that the structure has aconcaveform at the core region of the plasma column, as expected fromprevious FRC stud-ies. The axial array of the fibers shows that the separatrix boundaryis similar in shape to a racetrack when the FRC is long, extending tomirror regions of the confining field, and elliptical for a shortFRC. The equilibrium shape of the separatrix which is calculated usinga two-dimensional code also changes from elliptical to racetrack-likewith increase of the length in the mirror field, as observed in theexperiment.
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Masayuki Kawakami, Shuji Nishizaki, Toshizo Fujita
専門分野: Structure of liquids and solids; crystallography.
1995 年 64 巻 11 号 p.
4081-4083
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
X-ray powder diffraction measurements were made of the intermetallicFe
2VSi compound. At 300 K, Fe
2VSi has the L2
1-type structurewith the lattice parameter a=5.674 Å, but it exhibits atetragonal deformation at low temperatures. The lattice parametersobtained at 10 K are c=5.623± 0.003 Å, a=5.688± 0.001 Åand c/a=0.989.
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Tomotoshi Nishino, Kouichi Okunishi
専門分野: Thermal properties of condensed matter.
1995 年 64 巻 11 号 p.
4084-4087
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We propose a fast numerical renormalization group method-the productwave function renormalization group (PWFRG) method-for 1D quantumlattice models and 2D classical ones. A variational wave function, which is expressed as a matrix product, is improved through aself-consistent calculation. The new method has the same fixed pointas the density matrix renormalization group method.
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Tomi Ohtsuki, Yoshiyuki Ono
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 11 号 p.
4088-4091
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The level statistics in two dimensional disordered electron systems inmagnetic fields(unitary ensemble) or in the presence of strong spin-orbit scattering(symplectic ensemble) are investigated at the Anderson transitionpoints. The level spacing distribution functions P(s) are found to beindependent of the system size or of the type of the potentialdistribution, suggesting universality. They behave as s
2 in thesmall s region in the former case, while increase proportional tos
4 is seen in the latter.
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Junichi Okada, Isao Sawada, Yoshihiro Kuroda
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 11 号 p.
4092-4096
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Three decades ago, the quantum Langevin equation (Mori formula) wasused to reformulate the linear response theory (Kubo formula). Sincethen, the Mori formula has often been used to evaluate transportcoefficients, but only within the Born approximation. In the presentstudy, we obtain a rigorous expression for the transport coefficientsas a series expansion in terms of the projection operator. We thenevaluate the optical conductivity for a free electron system withimpurity scattering in order to discuss the mutual consistency betweenthe Mori formula and the Kubo formula.
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Taro Nagao
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 11 号 p.
4097-4100
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
It has been observed in experiments that the pronounced oscillationstructure in the magnetoresistance of a square antidot lattice isdrastically affected by an anisotropic deformation of the lattice. Weperform a numerical simulation on an anisotropic antidot lattice andobserve expected behavior in the magnetoresistivities. We discuss howthe classical theory of electron motion in an antidot lattice canexplain the observed anisotropy effect.
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Kiiti Siratori, Yasuaki Nakagawa, Hiroaki Kato, Kay Kohn, Eiji Kita
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4101-4104
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Magnetization, M, of EuS and Eu
1-xSr
xS (x≤ 0.4) was measuredbelow 90 K in an external magnetic field up to 150 kOe. It is shownthat M in the paramagnetic region is well expressed by a Brillouinfunction for S=7/2, with an effective field H+λ M. Even attemperatures below asymptotic Curie temperature, magnetizationapproaches the Brillouin function with increasing fieldstrength. Moreover, it is found that magnetization scaled by(T-T
c)
b can be expressed as a universal function of magneticfield scaled by (T-T
c)
b+c. Here, T
c is the ferromagneticCurie point. Scaling exponents, b and c, are very different from thosein the critical region. The exponent c is about 1.15 and independentof x whereas b is 0.14 for EuS and decreases rapidly with increasingx, proportionally to T
c.
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Nobuyuki Katoh, Masatoshi Imada
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4105-4108
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We investigate the mechanism of spin gap formation in atwo-dimensional model relevant to Mott insulators such asCaV
4O
9. From the perturbation expansion and quantum Monte Carlocalculations, the origin of the spin gap is ascribed to the four-siteplaquette singlet in contrast to the dimer gap established in thegeneralized dimerized Heisenberg model.
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Kazutoshi Ogoh, Chihiro Yamanaka, Motoji Ikeya, Eiji Ito
専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1995 年 64 巻 11 号 p.
4109-4112
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
X- and Q-band electron spin resonance (ESR) studies were performed ona radiation-induced defect in stishovite synthesized under highpressure from high-purity SiO
2 glass, followed by γ-rayirradiation using a source of
60Co at room temperature. An oxygenvacancy center which traps an electron (E' center) has an anisotropicg-factor of orthorhombic symmetry, g
x=2.0055, g
y=2.0044 andg
z=2.0023, an axial hyperfine structure due to
29Si (I=1/2), A
x=A
y=1.2 mT and A
z=8.5 mT, and an almost isotropicsuperhyperfine structure due to the second-nearest
29Si, A
shf=1.2 mT.
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Haruo Furuta, Yuhji Tsujimi, Yukihiro Shimada, Toshirou Yagi
専門分野: Dielectric properties and materials.
1995 年 64 巻 11 号 p.
4113-4116
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The quasi c
33 acoustic mode of ferroelectric TGS is observed byimpulsive stimulated Brillouin scattering. The mode is excited bypicosecond laser pulses at 500 MHz and 2.0 GHz and its vibrationalbehavior is probed in real time. The temperature dependence of thevelocity of the mode shows an anomaly through a piezoelectric couplingwith the fluctuating polarization below the transition temperatureT
c. The relaxation time τ
0 of the order of 10
-10 s·deg is obtained which is longer than these reported in the previousBrillouin scattering and the ultrasonic studies.
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Yutaka Moritomo, Taka–hisa Arima, Yoshinori Tokura
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1995 年 64 巻 11 号 p.
4117-4120
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Optical study of trivalent 3d transition metal oxide compoundsLaSrMO
4 (M=Cr, Mn, Fe and Co) with layered perovskite structure hasrevealed fundamental features of their electronicstructures. Systematic change of the charge-transfer gap (E
gap)with the 3d element (M) can be explained by a simple ionic model. Thespectrum below -- 7 eV is found to be strongly M-dependent, and isinterpreted in terms of multiplet splitting of the final 3d
N+1state.
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Hideaki Ujino, Miki Wadati
専門分野: Mathematical methods in physics.
1995 年 64 巻 11 号 p.
4121-4128
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
It is shown that the quantum inverse scattering method(QISM) and the exchange operator formalism, which are independentlydeveloped to deal with the quantum Calogero-Moser-Sutherland models, give exactly the same operator algebra in the space of wave functionsof identical particles.
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Masato Hisakado, Miki Wadati
専門分野: Mathematical methods in physics.
1995 年 64 巻 11 号 p.
4129-4134
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Motion of discrete surfaces (triangulate surfaces) in3-dimensional space is studied. The discrete surfaces are mapped tothe sphere S
2 and differential-difference equations are obtained torepresent the motion of the discrete surfaces on the S
2. Theseequations contain intrgrable dynamics. Relations between integrablesystems and the Gauss-Bonnet formula are discussed.
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Ryutaro Kanno, Noriyoshi Nakajima
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 11 号 p.
4135-4141
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
To analyze the generalized Brownian motion, i.e. the{fractional} Brownian motion, we propose a path integral which isgoverned by the modified action along the principal path with fractalnatures, i.e. mainly observable path in a diffusive phenomena. Bymodified the definition of the action and summing over fractal paths, the path integral is derived. We investigate several properties ofthis integral. The principal path has a fractal structure and the pathintegral represents the transition probability of the fractionalBrownian motion. The transition probability itself has no dependenceon the structure of principal paths. The path integral is mainlycharacterized by two parameters, the Hausdorff dimension D
H ofprincipal paths representing a microscopic structure and the Hurstcoefficient H representing a macroscopic structure, which areindependent of each other.
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Hiroaki Nakamura, Naomichi Hatano, Minoru Takahashi
専門分野: Statistical physics and thermodynamics.
1995 年 64 巻 11 号 p.
4142-4155
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The finite-size scaling function of the nonlinearsusceptibility of the ferromagnetic Heisenberg chain is givenexplicitly. It is conjectured that the scaling function is universalfor any values of S. The conjecture is based on the exact solution ofthe nonlinear susceptibility for S=∞, and numerical calculationsfor S=1/2 and S=1.
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Ryo Sugihara, Kazumi Nishimura
専門分野: Electricity and magnetism: fields and charged particles.
1995 年 64 巻 11 号 p.
4156-4162
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
A narrow electromagnetic beam propagating parallel to anexternal magnetic field in a plasma is considered theoretically. Thetheory assumes that the plasma pressure is larger than theelectromagnetic one. It is found that under the paraxial approximationthe beam having a Gaussian cross section can propagate. The Rayleighrange is enlarged or shortened depending on the dielectriccoefficients of the plasma. The beam is either right- or left-handpolarized and both modes have the longitudinal component of theelectric field as the Gaussian beam does in vacuum. The phasevelocities can become less than the light velocity c for some plasmaparameters for which those velocities of the plane R- and the L-wavesare always greater than c.
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Nabil T. M. Eldabe, Salwa M. G. Elmohandis
専門分野: Kinetic and transport theory of fluids; physical properties of gases.
1995 年 64 巻 11 号 p.
4163-4174
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Velocity profiles for unsteady pulsatile laminar flows ofviscoelastic non-Newtonian conducting fluids through a channel havederived using the perturbation method. The induced magnetic field andwall shear have been obtained. The effects of pulsation, elasticityand the magnetic parameter on the velocity, induced magnetic field andwall shear are discussed. Results are illustrated numerically andgraphically. It is found that amplitude of the pulsation increases thevelocity distribution which would be obtained under steady flowconditions at the same mean pressure gradient. The effect of both themagnetic and elasticity parameters decrease the velocitydistribution. Also the properties of the fluid on the induced magneticfield and the skin-friction are discussed.
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Taro Matumoto, Yuji Nakamura, Masahiro Wakatani
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4175-4184
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
MHD equilibrium and stability of LHD (Large HelicalDevice) are studied when circular plane magnetic axis is distortedinto spatial helical one by introducing unbalance between two helicalcoil currents. The helical axis effect increases rotational transformwith enhancing magnetic hill at zero beta, where beta is the ratio ofplasma pressure to magnetic pressure. The significant effect ofhelical magnetic axis is reduction of average radius of the outermostflux surface or elimination of edge region with large magnetichill. For finite beta plasmas this reduction of average plasma radiushas substantial stabilizing effect on pressure driven MHD modesthrough enhancement of magnetic well produced by both Shafranov shiftand helical shift of magnetic axis. However, by comparing the helicalaxis configuration of LHD to planer axis configuration with the sameradius produced by using limiter, the change of equilibrium andstability due to the helical axis is found weak in the LHD case. Themerit of the helical axis configuration is controllability of averageplasma radius without limiter.
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Jian Du, Tetsuya Ohata, Katsuji Shimoda, Katsumi HIRANO
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4185-4190
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Soft X-rays generated with a gas-puff pinch device is characterizedusing a pinhole camera which enables a quantitative intensitymeasurement, a Bragg imaging spectrometer and an X-ray diode. Aneutral argon shell whose line density was 8.1× 10
17 atoms/cm(M=5.5× 10
-5 g/cm) was formed between the electrodes. Thesoft X-rays were emitted for about 10 ns in the early stage of theplasma column formation. Highly localized and intense soft X-raysources, so-called hot spots, were observed in the pinched plasma. Theemitted energy was estimated to be 50± 15 J into 4π sr, for ArK-lines. The reproducibility of the X-ray emission are discussed.
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Hiroyuki Kitaoka, Atsushi Sakurai, Toshikazu Yamamoto, Katsuji Shimoda ...
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4191-4195
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
A plasma focus device with a fast acting valve is designedfor additional high z gas puff and is successfully operated to produceintense soft X-rays. Using the fast acting valve, high z gas isinjected to the pinch region just before the discharge to decouple theinitial phase for the current sheath formation from the pinchformation phase. Quantitative measurement of soft X-ray intensity andthe observation of the plasma behavior were simultaneously carried outfor the additional gas puff discharge and the conventional gas-filleddischarge. Experimental results show the enhancement of the soft X-rayemission in two order of the intensity.
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Naoyuki SATO, Rikizo Hatakeyama, Noriyoshi Sato
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4196-4208
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
A plasma potential formation is investigated in acollisionless magnetized plasma flow in the presence of localizedradio-frequency electric fields. An extremely large-amplitude electronplasma wave is generated by applying an external rf potential to aring exciter surrounding the plasma column. Steep changes of electrondensity, temperature and potential along the plasma flow are observedin the region around the wave generation, where the waves arelocalized because of enhanced wave damping. The phenomena drasticallychange in accordance with the characteristics of electron-wavepropagation. The local potential hill and subsequent large potentialdrop observed are attributed to the ponderomotive force on electronsand the nonlinear electron acceleration due to enhanced wave damping, respectively. This claim is supported by calculations based onone-dimensional Poisson's equation including spatial variations of thecharged particles' velocity distribution functions which are stronglyaffected by the localized highly-nonlinear waves.
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Hiroshi Shirai, Tomonori Takizuka, Osamu Naito, Masayasu Sato, Nobuaki ...
専門分野: The physics of plasmas and electric discharges.
1995 年 64 巻 11 号 p.
4209-4220
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Nondimensional local transport analysis of JT-60U plasmashas been carried out for NBI heated L-mode phase. Plasmas with thesame poloidal cross section and almost the same profiles ofnondimensional parameters such as ν
*, β
th, q, T
e/T
i except for ρ
* are compared. The ρ
*dependence of the one fluid thermal diffusivity, χ
eff, theelectron thermal diffusivity, χ
e, and the ion thermaldiffusivity, χ
i, has been examined. The property of χ
effis between the weak gyroBohm type diffusion and the Bohm typediffusion in the region a/3≤ r≤ 2a/3, which is consistent with theresults of the global confinement study done before. We have alsofound that χ
e is weak gyroBohm type diffusion while χ
itends to be Bohm like diffusion.
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Teruo Ogihara
専門分野: Structure of liquids and solids; crystallography.
1995 年 64 巻 11 号 p.
4221-4241
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
A theory of the cooperative Jahn-Teller effect is developed toelucidate a structural phase transition observed in the CsCuCl
3crystal. This theory establishes the relationship between the localand the cooperative Jahn-Teller effect. We find that the helicalalignment of Cl
- ions along the c-axis agrees with experimentaldata when the two Δ
6 modes of the phonons executed bythe Cl
- ions contribute to the structutal phase transition.
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Masayuki Hasegawa
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 11 号 p.
4242-4247
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Freezing of the hard spheres is re-examined using the modifiedweighted-density approximation (MWDA) of Denton and Ashcroft and thegeneralized effective-liquid approximation (GELA) of Lutsko andBaus. It is found that one owes part of success of these theories tothe use of the Percus-Yevick (PY) direct correlation function and thecorresponding equation of state of uniform fluids as the input data inthese theories. In fact, if one uses virtually “ exact'' inputdata in place of the PY ones, the free energies of the solid phase aresomewhat lowered and predicted freezing properties worsen. It isargued that this unfavorable feature of the MWDA and the GELA becomesmuch more serious when these theories are applied to the referencehard spheres in the thermodynamic perturbation approach to freezing ofsystems with long-ranged potentials.
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Masayuki Hasegawa
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 11 号 p.
4248-4257
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Systematic investigations are made of the thermodynamic perturbationapproach to freezing, which has proved successful for systemsinteracting through soft-core or long-ranged potentials. The classicalone-component plasma (OCP) is taken as the extreme case of suchsystems and the investigations focus on the reference systems employedin this approach and on the approximation schemes used to treat thatsystem. It is confirmed that good results are obtained for thefreezing properties of the OCP if a system with repulsive, short-ranged potential is properly chosen as the reference system, andboth this system and the remaining part due to the long-rangeinteraction are separately treated by the modified weighted-densityapproximation (MWDA) using accurate input data. However, if we adoptthe hard spheres as the reference system in this approach and useeither the MWDA or the generalized effective-liquid approximation(GELA) for this system, we cannot get similar results unless we usethe input data in the Percus-Yevick (PY) approximation rather than thevirtually “ exact'' ones. This unfavorable result throwsserious doubt on the usefulness of the hard spheres as the referencesystem.
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Hisashi Haga, Ryusuke Nozaki, Yoichi Shiozaki, Kenji Ema
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 11 号 p.
4258-4264
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Heat capacity of K
2ZnCl
4 and K
2SeO
4 has beenmeasured using a high-resolution ac calorimeter. Critical behavior ofthe heat capacity anomalies associated with the normal-incommensurate(N-INC) phase transitions has been analyzed with the preasymptoticrenormalization-group expression which includes correction terms up tothe second order. It is revealed that the heat capacity anomalies ofK
2ZnCl
4 and K
2SeO
4 are described well with the threedimensional (3D) XY model; the critical exponent, the criticalamplitude ratio and the dimensionless ratio derived from thefirst-order correction terms agree well with the theoreticallyexpected values of 3D XY model. These results are consistent with ourprevious experimental result for Rb
2ZnCl
4 and the Cowley andBruce's prediction that the N-INC phase transition is classified intothe 3D XY system.
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Kazuo Gesi
専門分野: Equations of state, phase equilibria, and phase transitions.
1995 年 64 巻 11 号 p.
4265-4269
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The low-temperature phase transition in N(CD
3)
4MnCl
3 (DTMMnC)has been studied by dielectric measurements. The transitiontemperature of DTMMnC is 126.4 K at zero pressure, which is almostunchanged from that of the normal compound N(CH
3)
4MnCl
3(TMMnC). The effect of deuteration on the pressure-temperature phasediagram is also insignificant: the deuteration lowers the criticalpressure at which the pressure-induced phase (Phase III) appears byabout 10 MPa. The isotope-effect is compared with that in[N(CH
3)
4]
2MnCl
4-type compounds and discussed.
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Shigenori Tanaka
専門分野: Electron states in condensed matter.
1995 年 64 巻 11 号 p.
4270-4277
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The electronic structure of NiO solid with the fcc type-IIantiferromagnetic structure has been studied using a variationalquantum Monte Carlo approach. The Jastrow-Slater many-body wavefunction has been used for valence electrons, and the pseudopotentialshave been evaluated with the aid of a local approximation. Thecalculated results for the binding energy and the structuralproperties are in good agreement with experiment. Reasonableevaluations have also been made for the charge and spin densitydistributions and the electron-electron radial distributionfunctions. Although the results for the one-particle energydistribution and the charge-transfer excitation energy gap areencouraging, further increase in Monte Carlo steps and improvements incomputational methods would be required for the detailed comparisonwith experiments and the most dependable density-functional bandcalculations.
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Shin–ichi Kimura, Yasuhiko Sato, Fumitaka Arai, Mikihiko Ikezawa ...
専門分野: Electron states in condensed matter.
1995 年 64 巻 11 号 p.
4278-4288
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The electronic structures of a magnetic semiconductorCe
3Au
3Sb
4 and the related materials, La
3Au
3Sb
4 andPr
3Au
3Sb
4, have been investigated by reflectivity andresonant photoemission spectra. From the resonant photoemissionspectra of Ce
3Au
3Sb
4, the hybridization between the Ce4fstate and the Sb5p valence band was found to be weak. This result isconsistent with the electronic structure which is derived from theanalysis of the optical data about the energy gap. The experimentallydetermined electronic structure is compared with a band calculation ofLa
3Au
3Sb
4. The unoccupied 4f state is concluded to be about3 eV above the Fermi level, which is higher by 2 eV than the resultof the band calculation. The exciton like absorption due to thetransition from 4f to 5d states was observed. The intra-atomic Coulombinteraction between 4f and 5d states is thought to play an importantrole.
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Satoru Ohno, Tatsuya Okada
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 11 号 p.
4289-4295
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The dependence of the electrical conductivity on concentration forliquid Sn
1-cSe
c alloys exhibited a sharp minimum and a broadmaximum at the composition c=0.5 and 2/3, respectively. The dependenceof the thermopower on concentration exhibited a typical { p-n} transitionat the stoichiometry SnSe. The electrical behaviour of liquidSn
1-cSe
c alloys with c ≤0.3 was explained by the decrease in theconduction electrons due to the formation of chemical bonds between Snand Se ions. The conductivity and thermopower near the stoichiometrySnSe were analyzed by using the equations derived from theKubo-Greenwood formula. The conductivity gap was about 0 eV forliquid Sn--Se alloys near the stoichiometry.
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Tetsuo Kondo, Kazuya Suzuki, Toshiaki Enoki
専門分野: Electronic transport in condensed matter.
1995 年 64 巻 11 号 p.
4296-4307
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We investigated transport properties for incommensurate misfit layercompounds (CeS)
1.19(TiS
2)
n (n=1, 2) with stage-1 and stage-2structures. Both materials showed metallic conduction. The Hall effectshowed that the electrical conduction is dominated by the electroncarriers for both compounds, while thermoelectric power of stage-1(CeS)
1.19TiS
2 had a positive value of +5 μV/K at roomtemperature. This proved that the two different energy bands overlapat E
F of stage-1 (CeS)
1.19TiS
2. Detailed analysis of thethermoelectric power revealed the existence of short rangedomain-boundary phonon scattering process, where the mean free path isestimated to be of the order of 10 Å. This means that thelocal-lattice modulation induced by the incommensurate structure has aremarkable effect on the scattering process of the acoustic phonons aswell as the conduction electrons.
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Hideaki Kasai, Naoya Okamoto, Ayao Okiji
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1995 年 64 巻 11 号 p.
4308-4316
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Effects of electronic excitations are investigated on thetranslational energy distribution of ions scattered by metalsurfaces. Coupling between the translational motion of ion and degreesof freedom of metal electron system is taken into account explicitly, in the framework of model consisting of the non-interactingNewns-Anderson Hamiltonian for the electron system and translationalenergy of the ion. It is shown by perturbational calculation thatwithin the Born-Oppenheimer approximation (BOA), a logarithmicsingularity comes out in the energy distribution of ions scattered bymetal surfaces as a Fermi surface effect. Further, it is shown thatbeyond BOA this singularity is weakened by interplay betweenelectronic state transitions and state changes of ion motion duringscattering process.
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Akimasa Sakuma
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1995 年 64 巻 11 号 p.
4317-4321
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
To investigate the magnetic performance of a hybrid structure oftransition metals, we consider the Fe
3Pt/Fe system and examine theeffects both of the tetragonal distortion of L1
2 type Fe
3Pt andthe hybridization with bcc-Fe on the magnetic properties, usingLMTO-ASA method in the framework of LSD. The magnetic moment ofFe
3Pthas a maximum stationary value of 8.85 μ
B/cell atc/a=1/√2. The hypothetical struc-ture of Fe
20Pt
4 is supposed by combining Fe
3Pt of c/a=1/√2 and bcc-Fe lattice. It is predicted that the magnetizationreaches 2.27 T with the magnetic anisotropy constant of 11×10
5 J/m
3. With using the coherent rotation model formagnetization reversal process, we get maximum energy product(BH)
max=10.2 MJ/m
3.
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Takeshi Narushima, Tota Nakamura, Satoshi Takada
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4322-4330
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The ground-state phase diagram of the S=1/2 XXZ laddermodel is investigated by using the density-matrixrenormalization-group method. This model is composed of two S=1/2 XXZchains with ferromagnetic rung couplings (λ ) and intra-chainanisotropy (Δ), and continuously changes from the twoindependent S=1/2 XXZ chains at λ =0 to the S=1 XXZ chain in thelimit of λ → ∞ . It is shown that there existedge states at Δ=1 and λ =1 in relation to thefour-fold degeneracy of the ground state and that an excitation gapopens nearly at λ =0 for 0.8≤ Δ≤ 1. In addition, it is clarified that the transition between the Haldane phase and theantiferromagnetic phase occurs at λ =1.15 ± 0.01 forΔ=1. A possible phase diagram in the λ -Δplane is proposed, which is consistent with the scaling analysis basedon the bosonization method.
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Kenro Kawano, Minoru Takahashi
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4331-4344
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The logarithmic correction terms in the repulsive Hubbardchain is investigated by using the Bethe Ansatz. The magneticsusceptibility χ of this model has a field dependent logarithmiccorrection term in small magnetic field at zero-temperature. This termcauses ∂ χ /∂ h|_{h=0}=∞ . In arbitrary nand U the existence of the logarithmic correction term is shown forthe susceptibility. We consider how this term depends on n and U. Wealso discuss the logarithmic correction term of the super-symmetric t-J model.
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Mikito Koga, Hiroyuki Shiba
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4345-4362
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The Kondo effect due to U-type impurities is studied in connectionwith the stability of the Fermi liquid and the non-Fermiliquid. First, an effective exchange Hamiltonian in terms ofirreducible tensor operators is derived for conduction electrons, which are coupled with plural 5f electrons. It is based on theassumption of strong spin-orbit and Hund couplings. Second, a modelfor f
2 configuration placed in a tetragonal or hexagonal crystalfield is studied by simplifying the internal structure as thenon-Kramers doublet ground state and the first singlet excitedstate. The numerical renormalization group analysis shows that thesinglet excited state plays an important role to stabilize the Fermiliquid over the non-Fermi liquid. Third, the difference of the Kondoeffect is examined between non-Kramers doublet for f
2 and Kramersdoublet for f
3 in the presence of the cubic crystal field. It isshown that for f
3 the Hund coupling reduces the channel number toone, while the situation is different for f
2.
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Yasuaki Oohara, Yasushi Okayama, Hiroki Takahashi, Hideki Yoshizawa, N ...
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4363-4370
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Neutron diffraction measurements were performed on CeAs under highpressure. Above the critical pressure, P
c=1.1 GPa, twomagnetically ordered phases appear. The ferromagnetic ordering isestablished in the upper temperature phase. The type-I ordering isestablished in the lower temperature phase in addition to theferromagnetic ordering, which brings about the canted spinstructure. The temperature dependence of the Bragg intensity of thetype-I ordering has a long tail above the Néel temperature. Theferromagnetic moment increases with increasing pressure, while theantiferromagnetic moment decreases particularly above 2.0 GPa. Thetotal magnetic moment, which is the expected Γ
7 valuebelow P
c, decreases abruptly at P
c.
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Naoshi Ikeda, Kay Kohn, Etsuko Himoto, Midori Tanaka
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4371-4377
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We observed a few magnetic relaxation phenomena in a LuFeMgO
4single crystal, that is, the difference in the magnetization betweenfield-cooled and zero-field-cooled specimens, the appearance ofthermoremanent magnetization, and the frequency dependence of the cusptemperature of AC susceptibility. The observed relaxation wasinterpreted in terms of thermal fluctuations and freezing of themagnetic clusters which are supposed to exist in this substance.
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Seishi Takagi
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4378-4381
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The magnetic properties of honeybees have been investigated bymeasuring their susceptibility, magnetization andelectron-spin-resonance (ESR) absorption. The abdomen of adult workerhoneybees shows typical paramagnetism with small magnetic remanencedown to 4.2 K, while the other parts of the honeybees are apparentlydiamagnetic. The paramagnetism of the abdomen seems to develop not inthe pupal stage but after coming out of comb. Drones show noparamagnetism, but a queen bee seems to have some paramagnetic speciesin her abdomen.
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Hiroshi Ajiki, Tsuneya Ando
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4382-4391
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Magnetic properties of carbon nanotubes (CN's) are studied in a k·p model. In a magnetic field perpendicular to the tube axis, themagnetization is essentially determined by that of a graphite sheet, while it is induced also by the Aharonov-Bohm (AB) effect in aparallel field. The AB effect manifests itself in the magnetic-fieldand temperature dependence of the differential susceptibility even forensembles of CN's having various circumferences and orientations. Themagnetic properties depend also on carrier doping.
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Youichirou Iino, Masatoshi Imada
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4392-4401
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We investigate temperature dependence of spin correlations in the one-dimen-sional Hubbard model at or close to half filling by the quantum MonteCarlo method. The numerical data are analyzed by introducing acrossover generated from an interplay of the intrinsic correlationlength and the thermal correlation length. It provides a unifiedpicture of the spin correlation of the metallic phase near the Mottinsulator at finite temperatures. Our results show that the crossover, not taken account by the conventional renormalization group and theconformal field theory, becomes more and more important to understandthe spin correlation near the Mott transition point.
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Masaki Mito, Masakazu Ito, Tatsuya Kawae, Masako Hitaka, Hiroyuki Degu ...
専門分野: Magnetic properties and materials.
1995 年 64 巻 11 号 p.
4402-4410
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
We measured the magnetic heat capacity, susceptibility andmagnetization of (CH
3)
4NCo(NO
2)
3 (TMCON) which is theiso-structural compound with the Haldane compound(CH
3)
4NNi(NO
2)
3 (TMNIN). From the analysis of thesethermodynamic properties, we found that TMCON is a one-dimensionalS=1/2 Ising system where the ferromagnetic nearest neighborinteraction J
1 and the antiferromagnetic next-nearest neighborinteraction J
2 are competing. The value of J
1 is estimated to beJ
1/k
B=28.0± 4.0 K. It is confirmed that the results can becomprehensively explained only when we take J
2<0, althoughJ
2=-0.22J
1 estimated from the thermal analysis differs fromJ
2=-0.46J
1 from the magnetic susceptibility for the powderedsample. Based on the results for TMCON, we discuss the stabilizationof the Haldane state in TMNIN, considering the frustration effectbetween J
1 and J
2.
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Masayuki Kawakami, Susumu Uwanuyu, Tomohiro Nagano, Takeshi Shinohara
専門分野: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1995 年 64 巻 11 号 p.
4411-4417
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Hyperfine fields have been measured by the NMR spin-echo technique inzero external field at 4.2 K for intermetallic compoundsFe
2Mn
1-xV
xSi and Fe
2T
1-xCr
xSi (T=V, Mn). Theaverage Fe and Mn magnetic moments are derived using the relationsbetween the hyperfine fields and the atomic magnetic moments in theisomorphic compounds. These moments in Fe
2Mn
1-xV
xSi increasemonotonically with increasing x; for Fe from 0.35μ
B at x=0.2 to0.5μ
B at x=0.75; and for Mn from 2.4μ
B atx=0.2 to 3μ
B at x=0.8. The extrapolation to the V-rich side gives 0.5μ
B/Fe in Fe
2VSi, which is consistent with an extrapolatedsaturation moment of 1.1μ
B/f.u. The results inFe
2T
1-xCr
xSi (T=V, Mn) are also discussed. From thesetogether with saturation moments the transition from a ferromagneticto an antiferromagnetic ordering on the V-rich side inFe
2(Mn, V)Si and Fe
2(V, Cr)Si is suggested.
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Tatsuo Komori, Koji Hukushima, Hajime Takayama
専門分野: Dielectric properties and materials.
1995 年 64 巻 11 号 p.
4418-4425
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Slow dynamics in the ± J Ising model on a square lattice is studiedby means of Monte Carlo simulation, in which the distribution functionof (logarithms of) relaxation times, P(x) with x=ln τ, isobtained by analyzing individual spin auto-correlation functions oneby one. At each temperature in the \lsquo Griffiths phase', namely inthe range above the spin-glass transition temperature T
c (=0) butbelow the Curie temperature of the corresponding pure ferromagnetTpurec, P(x) exhibits a characteristic crossover behavior at aroundx
c(=ln τ
c) which diverges toward T
c. Thecontributionsto the branch x ≤ x
c are interpreted due to the ordinary criticalslowing down process associated with T
c (critical dynamics). Thebehavior of P(x) at x≤ x
c, on the other hand, is quite consistentwith the picture of relaxation processes of large, rare clustersrelated to the expected Griffiths singularity at Tpurec (clusterdynamics).
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Tomoyuki Nagaya, Yoshihiro Ishibashi
専門分野: Dielectric properties and materials.
1995 年 64 巻 11 号 p.
4426-4433
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
Domain structures formed by quench in the NaNO
2-type crystals, whose incommensurate phase transition can be reproduced by thethermodynamic potential with no Lifshitz invariant, have been studiedby solving the kinetic equation numerically, adopting atwo-dimensional model. The temporal evolution of domain structures, consisting of positive and negative domains, is shown and analyzed. Ithas turned out that in the early stage the amplitude of the modulationwave with a specific wavenumber grows up and then the phase approachesthe stable state.
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Sayumi Hirose, Masao Kamada
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1995 年 64 巻 11 号 p.
4434-4441
発行日: 1995/11/01
公開日: 1999/10/01
ジャーナル
認証あり
The time response of photon-stimulated desorption (PSD) ofexcited-state alkali atoms from alkali halides has been investigatedwith synchrotron radiation pulses. It was found that the substancehaving a larger Rabin-Klick parameter shows a larger efficiency of thefast desorption. It was also found that there is a delay for the fastPSD, indicating the existence of the precursor state. It is proposedthat the fast desorption may be produced by electronic transition inthe surface layer, while the slow desorption may be due to the thermalinstability of surface defects.
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