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Condensed Matter papers — page 166

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Zeroth Sound Modes of Dilute Fermi Gas with Arbitrary Spin
Motivated by the recent success of optical trapping of alkali bosons, we have studied the zeroth sound modes of dilute Fermi gases with arbitrary spin-f, which are spin-S excitations ($0≤ S≤…
S-K. Yip, Tin-Lun, HoOct 6, 1998
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Exploring structural mechanisms in disordered materials using the activation-relaxation technique
Structural mechanisms in disordered materials like amorphous semi-conductors and glasses can be explored with the activation-relaxation technique (ART). The application of a sequence of such…
G. T. Barkema, Normand MousseauOct 6, 1998
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Photophysical Properties in C60 and Higher Fullerenes
The optical excitations in C60 and higher fullerenes, including isomers of C76, C78, and C84, are theoretically investigated. We use a tight binding model with long-range Coulomb…
Kikuo HarigayaOct 6, 1998
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The microscopic spin-phonon coupling constants in CuGeO3
Using RPA results, mean field theory, and refined data for the polarization vectors we determine the coupling constants of the four Peierls-active phonon modes to the spin chains of CuGeO3. We then…
R. Werner, C. Gros, M. BradenOct 5, 1998
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Van der Waerden's Colouring Theorem and Weak-Strong Duality on the Lattice
Van der Waerden's (VDW) colouring theorem in combinatoric number theory [1] has scope for physical applications.The solution of the two colour case has enabled the construction of an explicit…
Debashis Gangopadhyay, Ranjan ChaudhuryOct 3, 1998
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Modulation of the dephasing time for a magnetoplasma in a quantum well
We investigate the femtosecond kinetics of optically excited 2D magneto-plasma. We calculate the femtosecond dephasing and relaxation kinetics of the laser pulse excited magneto-plasma due to bare…
M. W. Wu, H. HaugOct 3, 1998
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A Real-Space Full Multigrid study of the fragmentation of Li11+ clusters
We have studied the fragmentation of Li11+ clusters into the two experimentally observed products (Li9+,Li2) and (Li10+,Li) The ground state structures for the two fragmentation channels are found by…
Francesco Ancilotto, Philippe Blandin, Flavio ToigoOct 2, 1998
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Wetting of Argon on CO2
We have studied the wetting transition of Ar adsorbed on solid CO2 by means of high-precision adsorption isotherms measured with a quartz microbalance. We observe triple-point wetting. At variance…
Giampaolo Mistura, Francesco Ancilotto, Lorenzo Bruschi et al.Oct 1, 1998
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Magnetically and thermally modulated microwave absorption in Y-Ba-Cu-O single crystal near Tc
The microwave absorption R in the Y-Ba-Cu-O single crystals was investigated near Tc ≈ 92 K and in the external magnetic field 0<H ≤ 9 kOe. A modified ESR spectrometer was used in the…
M. K. Aliev, G. R. Alimov, I. Kholbaev et al.Oct 1, 1998
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Mossbauer effect for dark solitons in Bose-Einstein condensates
We show that the energetic instability of dark solitons is associated with particle-like motion, and present a simple equation of motion, based on the Mössbauer effect, for dark solitons propagating…
Th. Busch, J. R. AnglinSep 30, 1998
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Exact diagonalization of the S=1/2 Heisenberg antiferromagnet on finite bcc lattices to estimate properties on the infinite lattice
Here we generate finite bipartite body-centred cubic lattices up to 32 vertices. We have studied the spin one half Heisenberg antiferromagnet by diagonalizing its Hamiltonian on each of the finite…
D. D. Betts, J. Schulenburg, G. E. Stewart et al.Sep 30, 1998
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Statistical Features in Learning
We study some features of learning models based on "delayed" and undifferentiated reinforcement and realized by simple algorithms which may be considered of a very elementary nature. We show…
Ion-Olimpiu StamatescuSep 30, 1998
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New integrable model of correlated electrons with off-diagonal long-range order from so(5) symmetry
We present a new integrable model for correlated electrons which is based on a so(5) symmetry. By using an η-pairing realization we construct eigenstates of the Hamiltonian with off-diagonal…
Angela Foerster, Jon Links, Itzhak RoditiSep 29, 1998
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Current responsivity of semiconductor superlattice THz-photon detectors
The current responsivity of a semiconductor superlattice THz-photon detector is calculated using an equivalent circuit model which takes into account the finite matching efficiency between a detector…
Anatoly A. Ignatov, Antti-Pekka JauhoSep 29, 1998
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Breathers on lattices with long range interaction
We analyze the properties of breathers (time periodic spatially localized solutions) on chains in the presence of algebraically decaying interactions 1/rs. We find that the spatial decay of a…
S. FlachSep 29, 1998
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Oscillation Frequencies for a Bose Condensate in a Triaxial Magnetic Trap
We investigate the dynamics of a Bose condensate, interacting with either repulsive or attractive forces, confined in a fully anisotropic harmonic potential. The (3+1)-dimensional Gross-Pitaevskii…
E. Cerboneschi, R. Mannella, E. Arimondo et al.Sep 28, 1998
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Anderson localization due to spin disorder: a driving force of temperature-dependent metal-semiconductor transition in colossal-magnetoresistance materials
We study temperature induced metal-insulator transition in doped ferromagnetic semiconductors, described by s-d exchange model. The transition is a result of the mobility edge movement, the disorder…
Eugene Kogan, Mark AuslenderSep 28, 1998
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Hidden spin-current conservation in 2d Fermi liquids
We report the existence of regimes of the two dimensional Fermi liquid that show unusual conservation of the spin current and may be tuned by varying some parameter like the density of fermions. We…
Paulo F. Farinas, Kevin S. Bedell, Nelson StudartSep 27, 1998
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Polarization and Strong Infra-Red Activity in Compressed Solid Hydrogen
Under a pressure of ~150 GPa solid molecular hydrogen undergoes a phase transition accompanied by a dramatic rise in infra-red absorption in the vibron frequency range. We use the Berry's phase…
Ivo Souza, Richard M. MartinSep 25, 1998
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Excitation spectrum of the two-dimensional attractive Hubbard model
We calculate the one-particle spectral functions above the superconducting transition temperature TC, in the framework of a functional integral approach. The coupling of the electronic…
Massimiliano Capezzali, Hans BeckSep 25, 1998
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Dynamical response functions in models of vibrated granular media
In recently introduced schematic lattice gas models for vibrated dry granular media, we study the dynamical response of the system to small perturbations of shaking amplitudes and its relations with…
Mario NicodemiSep 25, 1998
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Study of the critical properties of the Quantum Hall Fluid in the framework of a dual statistical model
By using Renormalization Group methods we analyze the description of the Quantum Hall Fluid in terms of a dual plasma with dyons as effective degrees of freedom. The physical interpretation of the…
G. Cristofano, G. Maiella, D. Giuliano et al.Sep 25, 1998
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The n∞ limit of O(n) model on graphs
Thirty years ago, Stanley showed that an O(n) spin model on a lattice tends to a spherical model as n∞. This means that at any temperature the corresponding free energies coincide. This…
Raffaella Burioni, Davide Cassi, Claudio DestriSep 24, 1998
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Directed polymers on a Cayley tree with spatially correlated disorder
In this paper we consider directed walks on a tree with a fixed branching ratio K at a finite temperature T. We consider the case where each site (or link) is assigned a random energy uncorrelated in…
Yadin Y. GoldschmidtSep 24, 1998
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Anomalous roughening of wood fractured surfaces
Scaling properties of wood fractured surfaces are obtained from samples of three different sizes. Two different woods are studied: Norway spruce and Maritime pine. Fracture surfaces are shown to…
Stephane Morel, Jean Schmittbuhl, Juan M. Lopez et al.Sep 24, 1998
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