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Akinori Nishino, Hideaki Ujino, Miki Wadati
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
701-704
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Through the q-deformation of the method developed by Takamura and Takano for the nonsymmetric Jack polynomials, we present the Rodrigues formula for the nonsymmetric Macdonald polynomials.
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Ho–Young Kwak, Yoon Pyo Lee, Sarng Woo Karng
専門分野: Fluid dynamics.
1999 年 68 巻 3 号 p.
705-708
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The propagation of a pressure wave induced by the rapid bubble wall motion near the bubble collapse was studied analytically for a sonoluminescing gas bubble. It has been found that a pressure wave rather than a shock wave is launched into the bubble center just prior to the bubble collapse and the wave is reflected near the center. It has also been found that as the gas pressure inside the bubble increases, so the reflection point moves farther from the center. No sharp focusing developed by an inwardly moving shock wave reflected at the origin has been found. The temperature rise associated with the pressure wave developed inside the bubble turns out to be insufficient for emitting light.
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Seiji Taki, Kazuyoshi Sagara, Tsutomu Kadotani, Shoichi Kai
専門分野: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1999 年 68 巻 3 号 p.
709-711
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Systematic observations are carried out on the molecular alignment in monolayers of mixtures of n-cyanobiphenyl (nCB) liquid crystals such as n=7CB to 12CB on a molybdenum disulfide substrate (MoS
2) using a scanning tunneling microscope. Several different types of specific alignments of the mixtures are observed depending on the mixture rate and the combination of nCB. There are also mixture combinations in which no specific alignment is observed.
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Toshifumi Itakura, Yoshikazu Suzumura
専門分野: Electron states in condensed matter.
1999 年 68 巻 3 号 p.
712-715
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We have examined spin density wave (SDW) state in a quasi-one-dimensional electron system with both commensurability of quarter-filled band and dimerization, which compete with each other. It is shown that there are two kinds of critical temperatures: T
c for the onset of the SDW state and T
c2 (< T
c) for another phase at low temperatures, where both phase transitions are of the second order. The former is pure 2k
F-SDW and the latter is followed by 4k
F-charge density wave with Fermi momentum, k
F.
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Masatsura Igami, Takeshi Nakanishi, Tsuneya Ando
専門分野: Electronic transport in condensed matter.
1999 年 68 巻 3 号 p.
716-719
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The conductance of carbon nanotubes with a vacancy is studied in a tight-binding model.We examine the Fermi energy ε dependence of the conductance and show it is quantized into zero, one, and two times the conductance quantum e
2/π(h/2π) depending on the type of vacancy in the half-filled case, i.e., ε = 0. In the presence of a magnetic field, the conductance is scaled by the component of the magnetic field in the direction of the vacancy.
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Mamoru Sakaue, Hideaki Kasai, Ayao Okiji
専門分野: Electronic structure and electrical properties of surfaces, interfaces and thin films.
1999 年 68 巻 3 号 p.
720-723
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The effect of Coulomb interactions between photoexcited electrons and holes on time-resolved two-photon photoemission from a metal surface is investigated with the aid of a simple model where the electron system consists of an sp-band, a d-band and free electron states above the vacuum level. A formula for the correlation trace (photoelectron intensity as a function of the pump-probe delay time) is derived by perturbation theory based on the Liouville equation and by treating Coulomb interactions within the Hartree-Fock approximation. It is demonstrated on the basis of the obtained results how Coulomb interactions affect the correlation trace.
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Masashige Matsumoto, Manfred Sigrist
専門分野: Superconductivity.
1999 年 68 巻 3 号 p.
724-727
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The chiral optical absorption by a single vortex in ap
x ± ip
y-wave superconductor is studied theoretically.The p
x±ip
y-wave state was recently suggested as the symmetryof the order parameter of Sr
2RuO
4 superconductor.Due to the violation of time reversal symmetry, there are two types of vortices whose winding orientation is the sameor opposite to the angular momentum of the Cooper pair. In a real material domains with p
x±ip
y-wave states are expected.However, optical absorption of circular polarized lightdepends only on the winding of the vortexand has a low energy absorption peak which results in dichroism.Dichroism occurs if superconductivity is realized on a single Fermisurface sheet. However, in the case of several Fermi surface sheets dichroism may disappear, if the both types of carriers are present, electron-like and hole-like. Therefore chiral optical absorption is a possible experimentto detect the orbital dependent superconductivitywhich was suggested as the superconducting state of Sr
2RuO
4.
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Ryusuke Ikeda
専門分野: Superconductivity.
1999 年 68 巻 3 号 p.
728-731
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The vortex glass (CVG) transition due to line-like (columnar) disorder, often called the Bose-glass transition, is examined at the mean field level and using the lowest Landau level approach to the Ginzburg-Landau model. The resulting transition field B
cvg(T) shows a linear behavior intemperature if it lies above the melting line in clean limit, in agreement with experimental data unexplained so far of YBCO in tesla range. Next, the key critical phenomena in this context, such as the precursors of the so-called transverse Meissner effect and the divergent in-plane conductivity σ
s, xx, are examined on the basis of the approach used previously to derive the VG scaling of σ
xx for the case of point disorder, and the obtained results together with the anisotropic scaling are consistent with those in the Boson mapping scenario. As a by-product, it is also shown that the present tilt response results for the 3D CVG transition imply a finite but nonuniversal critical conductance at the field-tuned superconductor-insulator transition in disordered thin films at T=0.
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Hitoshi Ohta, Tsuyoshi Tanaka, Susumu Okubo, Shojiro Kimura, Hikomitsu ...
専門分野: Magnetic properties and materials.
1999 年 68 巻 3 号 p.
732-735
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Millimeter and submillimeter wave ESR measurements on a single crystal of an S=1/2 Heisenberg ladder-like system Cu
2(C
5H
12N
2)
2Cl
4 have been performed using a pulsed magnetic field up to 16, T. The gap is estimated to be 9.7, K from the temperature dependence of ESR intensity. The detailed frequency dependence of ESR in the frequency region from 40 to 420, GHz at 1.8, K suggests magnetic transitions at H
c1=7.5, T, H
c2=10.1, T and H
s=13.2, T. A transition at 10.1, T is suggested for the first time. These results are discussed with previous magnetization measurements and theoretical calculations, and our results appear to be difficult to interpret according to the simple ladder model.
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Daisuke Akahoshi, Yutaka Ueda
専門分野: Magnetic properties and materials.
1999 年 68 巻 3 号 p.
736-739
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Three compounds, orthorhombic YBaCo
2O
5.5, tetragonal YBaCo
2O
5.5 and YBaCo
2O
5.0, have been synthesized and their structural, magnetic and electrical properties have been investigated.The structures of all three compounds have a CoO
2--Y(O)--CoO
2 block layer sandwiched between the BaO layers.Magnetic and metal-insulator transitions have been observed in orthorhombic YBaCo
2O
5.5 which has a one-dimensional ordering of oxygen atoms along the b-axis in the Y(O) layers. Tetragonal YBaCo
2O
5.5 and YBaCo
2O
5.0, which are both semiconductive, show magnetic transitions. The physical properties of YBaCo
2O
5+x strongly depend on the structure and oxygen content.
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Tatsuya Kawae, Masakazu Ito, Masaki Mito, Kazuyoshi Takeda
専門分野: Magnetic properties and materials.
1999 年 68 巻 3 号 p.
740-743
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We have studied the field dependence of the heat capacity of a typicalHaldane antiferromagnet (CH
3)
4NNi(NO)
3 (TMNIN) doped with thenonmagnetic impurity Zn
2+, as well as of a pure TMNIN. The overallfeatures of the magnetic heat capacity, including the characteristic broadmaximum, are almost reproduced by the theoretical curve with J/k
B =-12, K for both systems in zero field. The field dependence in the impuresystems is described well by assuming the Schottky heat capacity with S =1, not S = 1/2 expected from the VBS model. A possible reason why the S= 1 model is suitable is discussed.
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Naokazu Shibata, Hirokazu Tsunetsugu
専門分野: Magnetic properties and materials.
1999 年 68 巻 3 号 p.
744-747
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The finite-temperature density-matrix renormalization-group method is applied to the one-dimensional Kondo lattice modelnear half-filling to study its thermodynamics. The spin and charge susceptibilities and entropy are calculated down to T=0.03t. We find two crossover temperatures near half-filling.The higher crossover temperature continuously connects to the spingap at half-filling, and the susceptibilities are suppressed at around this temperature.At low temperatures, the susceptibilities increase again withdecreasing temperature when doping is finite. We confirm that the susceptibilities finally approach to the values obtained in the Tomonaga-Luttinger (TL) liquid ground state for several parameters.The crossover temperature to the TL liquid is a new energy scale determined from gapless excitations of the TL liquid.The transition from the metallic phase to the insulating phase is accompanied by the vanishing of the lower crossover temperature.
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Masahiro Matsumura, Masaki Horiike, Takashi Yokoyama, Hideki Yamagata
専門分野: Superconductivity.
1999 年 68 巻 3 号 p.
748-751
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The Cu NQR spectra were observed over the whole range of x in the paramagnetic state of Y
1-xPr
xBa
2Cu
3O
7-y. The NQR frequencies, ν
NQR, for both the Cu(2) and Cu(1) sites do not change significantly with increasingx. These results are in marked contrast to the variation of ν
NQR at the metal-insulator transition in YBa
2Cu
3O
x andLa
2-xSr
xCuO
4. This suggests that the doped holes inYBa
2Cu
3O
7 still remain in the CuO
2 plane even inPrBa
2Cu
3O
7, which conflicts with the hole-filling mechanism for thesuppression of the superconductivity in PrBa
2Cu
3O
7.Since our value of ν
NQR in PrBa
2Cu
3O
7 is differentfrom that presented in the previous report, the NMR spectrum in the antiferromagnetic orderedstate was reconsidered.
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Kozo Okada
専門分野: Optical properties and condensedmatter spectroscopy and other interactions of matter with particles and radiation.
1999 年 68 巻 3 号 p.
752-755
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The present paper discusses the role of U 5f-5f exchange interaction (J) in the inverse photoemission spectrum (IPES) and the U 4f x-ray photoemission spectrum (XPS) of uranium intermetallic compounds. The origin of the broad main peak in the IPES of UPd
3 and UPd
2Al
3, for instance, is ascribed to the exchange coupling effects of 5f electrons. In other words, whether the ground state is of high-spin or of low-spin is directly reflected in the width of the IPES. On the other hand, the interpretation for the U 4f photoemission spectrum is not so greatly influenced by J. The full-multiplet calculations are also performed for an U
4+ ion for comparison.
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Hiroshi Kakuhata, Kimiaki Konno
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
757-762
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We give a physical model of the O(3)-invariant coupled integrabledispersionless equations where a string with internal structure isinteracting to the external field.We derive loop soliton solutions through the bilinear equations in whichsolitons can move to positive and negative directions.We study two soliton interactions in detail.
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Alexandru Popa
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
763-770
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We have demonstrated in previous papers the following property: The energy which results from the Schrödinger equation can be rigorously calculated by line integrals of analytical functions, if the Hamilton-Jacobi equation, written for the same system, is satisfied in the space of coordinates by a periodical trajectory. We presented an accurate analysis model, based on this property. We present now the application of the model to the case of the boron and carbon atoms, to the ions with the same structure, and to the H
2 and Li
2 molecules.
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Zuonong Zhu, Hongci Huang, Weimin Xue
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
771-775
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
From a proper 2× 2 discrete isospectral problem, the relativistic Volterra lattice introduced by Suris and Ragnisco is rederived. So, a new Lax matrix for the relativistic Volterra lattice is given. Integrable discretization of the relativistic Volterra lattice is also obtained.
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Kazuhiro Hikami, Rei Inoue
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
776-783
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We study the Hamiltonian structure of the Bogoyavlensky lattice, which is an integrable differential-difference equation and is ageneralization of the Volterra model.We construct the lattice W algebras by use of the dynamicalvariables of the Bogoyavlensky lattice, and also show the bi-Hamiltonian structure thereof.The quantization of the lattice W algebras is briefly discussed.
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Yongtang Wu, Xianguo Geng
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
784-790
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The nonlinearization approach is generalized to the case of the Neumann constraint associated with a discrete 3× 3 matrix eigenvalue problem. A new symplectic map of the Neumann type is obtained by nonlinearization of the discrete eigenvalue problem and its adjoint one. A scheme for generating the involutive system of conserved integrals of the symplectic map is proposed, by which the symplectic map of the Neumann type is further proved to completely integrable. As an application, the calculation of solutions for the hierarchy of lattice soliton equations connected to the discrete eigenvalue problem is reduced to the solutions of a system of ordinary differential equations plus a simple iterative process of the symplectic map of the Neumann type.
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Yuji Igarashi, Katsumi Itoh, Ken Nakanishi
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
791-796
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
In a certain class of differential-difference equations for dissipative systems, we show that hyperbolic tangent model is the only the nonlinear system of equations which can admit some particular solutions of the Toda lattice. We give one parameter family of exact solutions, which include as special cases the Toda lattice solutions as well as the Whitham's solutions in the Newell's model. Our solutions can be used to describe temporal-spatial density patterns observed in the optimal velocity model for traffic flow.
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Akinori Nishino, Hideaki Ujino, Miki Wadati
専門分野: Mathematical methods in physics.
1999 年 68 巻 3 号 p.
797-802
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Extending a method developed by Takamura and Takano, we present the Rodrigues formula for the nonsymmetric multivariable Laguerre polynomials which form the orthogonal basis for the B
N-type Calogero model with distinguishable particles. Our construction makes it possible for the first timeto algebraically generate all the nonsymmetricmultivariable Laguerre polynomials with different parities for each variable.
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Nobuyasu Ito, Yukiyasu Ozeki, Hidetsugu Kitatani
専門分野: Statistical physics and thermodynamics.
1999 年 68 巻 3 号 p.
803-810
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Ferromagnetic (FM) transition of the ± J Ising model is studied for square and simple-cubic lattices by Monte Carlo simulations. Non-equilibrium relaxation (NER) process of magnetization from theall-aligned spin state is analyzed.The transition temperature is estimated at several values of FM bondconcentrations to provide the boundary of the FM phase.The estimated NER exponent of magnetization shows non-universalbehavior and it becomes larger smoothly when the transitiontemperature becomes higher.
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Kuniaki Nagayama
専門分野: Optics.
1999 年 68 巻 3 号 p.
811-822
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
A novel observation scheme, termed the complex observation, which is faithful to reconstruct optical images carried by either electromagnetic or material waves in their intrinsic complex form, is proposed. This observation is based completely on the coherent microscopy and comprised of a triple experiment consisted of twin experiments restoring two linear terms corresponding to the real and imaginary part of complex images and an additional experiment to cancel the square term which is in company with either linear term. A linear combination of three images obtained through the triple experiment is able to exhibit a complex quantity in the form to be numerically manipulated without rupture according to the formal theory of image formation. Manipulation of the phase and the intensity of primary waves penetrating through objects is the key in this observation.The basic scheme is applied to settle the long-standing issue in electron microscopy that the point resolution is impaired by the modulated contrast transfer, which originates from lens aberrations and defocusing. A computer simulation illustrates a modulation-free image with a drastic improvement on the contrast as well as the point resolution compared with the three originals utilized for the image reconstruction.
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Hideyuki Oka, Katsuya Ishii
専門分野: Fluid dynamics.
1999 年 68 巻 3 号 p.
823-832
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
In this paper, we study the behavior of gas bubbles rising through a viscous liquid in a vertical square duct numerically. The level set formulation developed by Sussman et al. is successfully generalized for three-dimensional incompressible two-phase flows including large density and viscosity ratios as well as surface tension effect. Numerical simulations are carried out for gas-liquid flows with different ratios of density. It is shown that the effect of variation of the density ratio on the bubble shape and the flow field is extremely weak when the ratio is larger than 1:50. The simulations of flows with a single bubble in a duct are also carried out to investigate the influence of the duct walls on the flow field. It is clarified that the bubble shape and the rising velocity strongly depend upon the ratio of a duct width to an initial bubble radius, but that there is hardly the effect of the ratio on the rising velocity when it exceeds ten. Finally, we present a numerical result on the interaction of two bubbles. The result is in qualitatively agreement with previous experimental data.
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Nobuaki Ikuta, Akihide Takeda
専門分野: Kinetic and transport theory of fluids; physical properties of gases.
1999 年 68 巻 3 号 p.
833-838
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The relaxation of the velocity distribution of gas particles proceeds only through collisions. The velocity dispersion probabilities through a collision draws the irreversible relaxation property clearly. The gas particles finally settle in the Maxwellian velocity distribution in which the energy exchange a collision is the maximum. The motive force to settle the gas particles in the Maxwellian velocity distribution is discussed with related problems.
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Takeshi Yanagidaira, Toshikazu Yamamoto, Katsumi Hirano
専門分野: The physics of plasmas and electric discharges.
1999 年 68 巻 3 号 p.
839-843
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Soft X-ray emitting spots (hot spots) generated in a plasma focus with a gas puffing are investigated using a streak mode imaging system for the soft X-ray region and a convex Bragg spectrometer which enables time resolved measurement. Using the imaging system, the typical size and lifetime of the hot spots in the focused neon plasma were measured to be {--} 1, mm in diameter, 13, mm in length and with a 5 -- 8, ns lifetime, approximately. The full width at half-maximum of the duration of the NeX (12.19, Å) 1s-2p and NeIX (13.447, Å) 1s
2-1s2p lines measured with the spectrometer agree with that measured with the imaging system. The soft X-ray emission started in the latter half of the plasma sustaining time measured by visible streak image and extinguished almost at the same time as the visible image. In the case of neon plasma, generation of the soft X-rays is not ascribed to the disruption of the plasma column, but to the growth of the macroscopic instabilities in the plasma column.After the disruption, the soft X-rays are not observed at all.The electron temperature and the density of the hot spots were estimated by several methods giving {--} 0.5, keV and in order of 10
21/cm
3, respectively.
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Ryutaro Kanno, Noriyoshi Nakajima, Masao Okamoto
専門分野: The physics of plasmas and electric discharges.
1999 年 68 巻 3 号 p.
844-847
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
A formula for the radial thermal conductivity of electron in a self-similar structure of magnetic field with islands, e.g. in the edge region of a stellarator equilibrium, has been derived for the collisionless limit. It is described by using the non-Gaussian process with fractal nature. We have shown that the electron thermal conductivity in the edge region is reduced, if magnetic islands are large enough.
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Kostyantyn N. Ostrikov, Sergey V. Vladimirov, Ming Y. Yu, Lennart Sten ...
専門分野: The physics of plasmas and electric discharges.
1999 年 68 巻 3 号 p.
848-851
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
High-frequency electrostatic surface waves at the interface of a dusty plasma and a dielectric wall are investigated. The effects of ionization, recombination, and dust-charge variationare taken into account in a self-consistent manner, sothat the system considered is closed. It is shown that a coupling of the surface waves and the dust-charge relaxation modeleads to anomalous damping and frequency downshift of the waves.
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Takeshi Yanagidaira, Toshikazu Yamamoto, Bing Shan, Katsumi Hirano
専門分野: The physics of plasmas and electric discharges.
1999 年 68 巻 3 号 p.
852-856
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Soft X-rays generated by a plasma focus device with an Ar gas puff are studied using a composite system which consists of an imaging Bragg spectrometer and a soft X-ray high speed imaging system.Two modes of soft X-ray emitting sources in Z-pinch plasma, filamentary and scattered spots, are generated in this experiment depending on the delay time from the gas puff to the main discharge.Spectroscopic observation revealed that even the case of the filamentary mode is not really filamentary but is actually X-ray emitting spots (hot spots) densely arranged in a column along the electrode axis.By using the soft X-ray high speed imaging system, the streak mode display is restructured from the data obtained in a single shot.Temporally resolved observations in streak mode showed that a spot appeared at a point near the electrode face first, then different hot spots appeared successively along the axis and in a direction away from the electrode face.It is clarified that the hot spot is a small region from which intense H-like and He-like spectral lines are emitted.The size and the distance between spots are from 0.1 to 0.5 mm in radius and -- 0.5 mm in length, respectively.The lifetime of the spots is 5 -- 10 ns.The average electron temperature and density calculated from the intensity ratio of those spectral lines are -- 1.8 keV and 1.7×10
22 /cm
3, respectively.They did not show a notable change along the axis.
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Takashi Aoyama, Yasuaki Hiwatari, Akira Ueda
専門分野: Structure of liquids and solids; crystallography.
1999 年 68 巻 3 号 p.
857-865
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
A molecular dynamics simulation is carried out to studythe structures of liquid Se and liquid Te in the semiconducting andmetallic states from a unified point of view.A classical system is used which consists of an assembly of chainswith monodisperse length. We assume that the interaction potentialsof pairs of atoms of different chains aredescribed by an inverse power potential, i.e. soft-core potentialε (σ/r)
n, and that the interactions are much softerin the metallic state than in the semiconducting state.The forces concerning the bonding, including geometricalconstraints between bonds are given by potentials of harmonic type.For semiconducting liquid Se the softness parameter n is set to be 24and for both metallic liquid Te and Se n to be 6 together withweak bond-stretching forces.Overall good agreements are obtained with the experimental results.The chain structure of our model realizes naturally shortand long bonds observed with EXAFS for liquid Te.Some information which may be useful for analyses of experimental datais also given.
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Kenji Nomura, Tetsuo Shingai, Naohiko Yasuda, Hidehiro Ohwa, Hikaru Te ...
専門分野: Equations of state, phase equilibria, and phase transitions.
1999 年 68 巻 3 号 p.
866-870
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The pressure dependence in the disordered Pb(In
1/2Nb
1/2)O
3 (PIN) single crystals (S=0.4 (type(I)), 0.2 (type(II))) were investigated by X-ray diffraction. The pressure dependence of the cell parameters and the integrated intensities of the (h/4 k/4 0) superlattice reflections associated with the antiparallel shift of lead cations were measured. The phase transition from the pseudo-cubic structure to the orthorhombic one was observed at about 0.4, GPa in the disordered-type(I) crystal. But no phase transition was observed below 0.8, GPa in the disordered-type(II) crystal. The disordered-type(I) crystal at higher pressure than 0.4, GPa was isostructural with the ordered crystal at the atmospheric pressure. But with increasing pressure in the disordered-type(I) crystal, the integrated intensities of the (h/2 k/2 l/2) reflections associated with the In/Nb arrangement did not change. The antiferroelectric phase was obtained not only by changing the In/Nb arrangement with isothermal annealing but also by applying pressure above 0.4, GPa in the disordered-type(I) crystal.
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Takeshi Yamao, Makoto Hagiwara, Kuniyuki Koyama, Motohiro Matsuura
専門分野: Equations of state, phase equilibria, and phase transitions.
1999 年 68 巻 3 号 p.
871-875
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
The intergrain ordering in a superconductive ceramic of YBa
2Cu
4O
8 at zero external magnetic field is investigated by AC resistivity measurements.The third harmonic in-phase voltage component V'
3ω to a weak AC current shows a distinct negative peak across the intergrain transition temperature T
C2, but not across the intragrain one T
C1 (T
C2 < T
C1).A divergence of the nonlinear resistivity ρ
2 is concluded at T
C2 in the limit of vanishing AC current, while the linear resistivity ρ
0 remains finite even at and below T
C2.Such characteristic critical behaviors of the intergrain ordering of the present superconductive ceramic strongly suggest a chiral glass ordering recently predicted to occur in high-T
C superconductive ceramics.
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Atsushi Mori
専門分野: Equations of state, phase equilibria, and phase transitions.
1999 年 68 巻 3 号 p.
876-880
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
Formulation describing the nonequilibrium steady-state(solid/liquid) interface motion in the language of continuummatter [A. Mori: J. Chem. Phys. 110, No. 16, in press] is extendedto the isothermal case.Equations derived from the mass- and the momentum-conservationare identical with those for the case without thermostating.However, equation derived from the energy-conservation iscombined with that derived from the second law of thermodynamics;as a result we express the chemical potential difference of thecoexisting two phases in terms of the specific volumes, net flow of mass in the liquid phase, and the viscosity term.
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Kazuaki Iwasa, Masahumi Kohgi, Hiroyuki Ohsumi, Keisuke Tajima, Tetsuy ...
専門分野: Thermal properties of condensed matter.
1999 年 68 巻 3 号 p.
881-886
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
X-ray diffraction studies at low temperatures have been performed in order to investigate thermal properties of crystal lattices in the low-carrier-density systemscerium monopnictides. CeP and CeAs show large crystal-lattice contractions with increasingtemperatures up to about 120, K and 90, K, respectively. Due to the strong p-f mixing, theexcited crystal fieldΓ
8-like state is expected to produce a shorter interatomic bond length betweencerium ions and neighboring pnictogens than that realized by the Γ
7 ground state.The experimental results of the lattice contractions at low temperatures are explained bythe thermal average of these crystal field states.
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Yoshio Miura, Hideaki Kasai, Wilson Agerico Diño
専門分野: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
1999 年 68 巻 3 号 p.
887-892
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We investigate and discuss the effects of the coupling betweenmolecular rotation and vibration on the dissociative adsorption andassociative desorption dynamics of D
2/Cu(111), with the aid of amodel Hamiltonian and the concept of a reaction path. In our modelHamiltonian, we take into account the molecular orientation dependenceof the reaction path curvature in the kinetic energy term. Wecalculate for the dissociative adsorption probability of D
2 as afunction of its initial translational energy, vibrational androtational states, using the coupled channel method. By invoking theprinciple of microscopic reversibility, we obtain the correspondingassociative desorption probability results for D
2 as a function of its final translational energy, vibrational and rotational states from thedissociative adsorption probability results. Furthermore, we showthat the calculation results qualitatively agree with experimental results.
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Takashi Yanagisawa
専門分野: Electron states in condensed matter.
1999 年 68 巻 3 号 p.
893-902
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We investigate the periodic Anderson model by a variational Monte Carlomethod. A new wave function is proposed based on the well-known Gutzwillerwave function. We calculate the physical properties using the MonteCarlo algorithm to consider the strong correlation effects.The ground state energy is improved considerably by taking into accountelectron-hole excitation effects.
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Hidekazu Nojiri
専門分野: Electron states in condensed matter.
1999 年 68 巻 3 号 p.
903-909
発行日: 1999/03/01
公開日: 1999/10/01
ジャーナル
認証あり
We apply self-consistent second order perturbation theory (SCSOPT)with respect to the on-site repulsive interaction Uto study the Hubbard model in two dimensions.We investigate single particle properties of the model over the entiredoping range at zero temperature.It is shown that as doping decreases toward half-fillingω-mass enhancement factor increases, while k-mass enhancement factor decreases.The increase in ω-mass enhancement factor is larger thanthe decrease in k-mass enhancement factor, so that total-mass is larger than that in the non-interacting case.When particle number density per unit cell n is given by0.64
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