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Condensed Matter papers — page 198

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Absence of spin gap in the superconducting ladder compound Sr2Ca12Cu24O41
Transport and 63Cu-NMR, Knight shift and T1, measurements performed on the two-leg spin ladders of Sr2Ca12Cu24O41 single crystals show a collapse of the gap in ladder spin excitations…
H. Mayaffre, P. Auban-Senzier, D. Jérome et al.Oct 7, 1997
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Density matrix renormalization group study of the polaron problem in the Holstein model
We propose a new density matrix renormalization group (DMRG) approach to study lattices including bosons. The key to the new approach is an exact mapping of a boson site containing 2N states to N…
Eric Jeckelmann, Steven R. WhiteOct 6, 1997
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A Study of the affect of N and B doping on the growth of CVD diamond (100):H 2 X 1 surfaces
We present a study of the effects of Nitrogen and Boron doping on the growth of CVD diamond in the (100) mechanism. These are the first calculations of this type and show that, in accordance with…
M. Kaukonen, R. M. Nieminen, P. K. Sitch et al.Oct 6, 1997
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On the integrability of the SU(N) Hubbard model
We exhibit explicitly the intertwiner operator for the monodromy matrices of the recent proposed SU(N) Hubbard model [5]. This produces a new family of non-additive R-matrices and generalizes an…
M. J. MartinsOct 5, 1997
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Beyond the Hubbard-I Solution with a One-Pole Self-Energy at Half-Filling with the Moment Approach: Non-Linear Effects
We have postulated a single pole for the self-energy, Σ(k,ω), looking for the consequences on the one-particle Green function, G(k,ω) in the Hubbard model. We find that G(k,ω)…
J. J. Rodriguez-Nunez, M. A. de MenezesOct 4, 1997
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The Two - Dimensional Attractive Hubbard Model: Highly Non-Linear Superconductivity With Sum Rules
We use the moment approach of Nolting (exact sum rules) (Z. Physik 255, 25 (1972)) for the attractive Hubbard model in the superconducting phase. Our diagonal and off - diagonal spectral functions…
J. J. Rodriguez - Nunez, C. E. Cordeiro, A. DelfinoOct 4, 1997
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Equivalence of the Calogero-Sutherland Model to Free Harmonic Oscillators
A similarity transformation is constructed through which a system of particles interacting with inverse-square two-body and harmonic potentials in one dimension, can be mapped identically, to a set…
N. Gurappa, Prasanta. K. PanigrahiOct 3, 1997
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Exactly integrable family of generalized Hubbard models with twisted Yangian symmetry
A strongly correlated electron system with controlled hopping, in the line of the recently proposed generalized Hubbard models as candidates for high Tc-superconductors, is considered. The model…
Anjan KunduOct 3, 1997
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Spectral Curves of Non-Hermitean Hamiltonians
Recent analytical and numerical work have shown that the spectrum of the random non-hermitean Hamiltonian on a ring which models the physics of vortex line pinning in superconductors is one…
J. Feinberg, A. ZeeOct 3, 1997
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Instanton in Disordered Peierls Systems
We study disordered Peierls systems described by the Fluctuating Gap Model. We show that the typical electron states with energies lying deep inside the pseudogap are localized near large disorder…
Maxim Mostovoy, Jasper KnoesterOct 3, 1997
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Single-Particle Diffusion-Coefficient on Surfaces with Ehrlich-Schwoebel-Barriers
The diffusion coefficient of single particles in the presence of Ehrlich-Schwoebel barriers (ESB)is considered. An exact expression is given for the diffusion coefficient on linear chains with random…
K. Mussawisade, T. Wichmann, K. W. KehrOct 2, 1997
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Diffusion process in a deterministically forced flow
We analyze circumstances under which the microscopic dynamics of particles which are driven by a forced, gradient-type flow can be consistently interpreted as a Markovian diffusion process. Special…
P. GarbaczewskiOct 2, 1997
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Traveling through potential energy landscapes of disordered materials: the activation-relaxation technique
A detailed description of the activation-relaxation technique (ART) is presented. This method defines events in the configurational energy landscape of disordered materials, such as a-Si, glasses and…
Normand Mousseau, G. T. BarkemaOct 2, 1997
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Thermodynamics of vortex lines in layered superconductors
We study the dissipative thermodynamics of vortex lines in layered superconductors within a simple string model in the dilute limit of negligible vortex interactions and compute the specific heat…
Roberto Iengo, Claudio A. ScruccaOct 1, 1997
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Quasi-excitations and superconductivity in the t-J model on a ladder
We study the t-J model on a ladder by using slave-fermion-CP1 formalism which is quite useful for study of lightly-doped high-Tc cuprates. By integrating half of spin variables, we obtain a…
I. Ichinose, T. MatsuiOct 1, 1997
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Rough droplet model for spherical metal clusters
We study the thermally activated oscillations, or capillary waves, of a neutral metal cluster within the liquid drop model. These deformations correspond to a surface roughness which we characterize…
N. Pavloff, C. SchmitSep 30, 1997
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Theory of Hall Anomaly in the Mixed State
Analogous to Peierls' arguments for the `anomalous' Hall in metals I demonstrate that the Hall anomaly in the mixed state of superconductors, the sign change of the Hall resistivity, is a…
P. AoSep 30, 1997
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Localization of Quasiparticles in an NS Structure
We discuss localization of quasiparticles in an extended NS structure in the situation when the reflection from the NS interface is mostly of Andreev kind. The localization of quasiparticle states…
A. V. Shytov, P. A. Lee, L. S. LevitovSep 30, 1997
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Electron Correlation and Jahn-Teller Interaction in Manganese Oxides
The interplay between the electron repulsion U and the Jahn-Teller electron-phonon interation ELR is studied with a large d model for the ferromagnetic state of the manganese oxides. These…
Naoto Nagaosa, Shuichi Murakami, Hyun Cheol LeeSep 30, 1997
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Bridged-assisted electron transfer. Random matrix theory approach
We discuss the effective donor/acceptor coupling for a bridged electron transfer system with a site-diagonal disorder of bridge energies. The average spectral properties of the system are discussed…
Ewa Gudowska-Nowak, Gabor Papp, Juergen BrickmannSep 30, 1997
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Vortex Dynamics, Resistivity Formula, and Fluctuation-dissipation Theorems
We investigate the problem of forces on moving vortex in a superfluid or superconductor. The main purpose is to locate the source which leads to the contradictory results in the literature. We…
X. -M. Zhu, P. AoSep 29, 1997
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Vortex lattice transition in D-wave superconductors
Making use of the extended Ginzburg Landau theory, which includes the fourth order derivative term, we study the vortex state in a magnetic field parallel to the c axis. The vortex core structure…
Jun'ichi Shiraishi, Mahito Kohmoto, Kazumi MakiSep 29, 1997
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Second harmonic generation in SiC polytypes
LMTO calculations are presented for the frequency dependent second harmonic generation (SHG) in the polytypes 2H, 4H, 6H, 15R and 3C of SiC. All independent tensor components are calculated. The…
Sergey N. Rashkeev, Walter R. L. Lambrecht, Benjamin SegallSep 29, 1997
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Dynamics of Ordering of Heisenberg Spins with Torque --- Nonconserved Case. I
We study the dynamics of ordering of a nonconserved Heisenberg magnet. The dynamics consists of two parts --- an irreversible dissipation into a heat bath and a reversible precession induced by a…
Jayajit Das, Madan RaoSep 27, 1997
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Phase separation of Bose-Einstein condensates
The zero-temperature system of two dilute overlapping Bose-Einstein condensates is unstable against long wavelength excitations if the interaction strength between the distinguishable bosons exceeds…
Eddy TimmermansSep 26, 1997
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