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Condensed Matter papers — page 155

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Barrier effects on the collective excitations of split Bose-Einstein condensates
We investigate the collective excitations of a single-species Bose gas at T=0 in a harmonic trap where the confinement undergoes some splitting along one spatial direction. We mostly consider…
P. Capuzzi, E. S. HernandezFeb 10, 1999
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Truncated-cone SPM tips for surface-molecules interaction studies
A new tecnique for the production of special shaped SPM tips is reported. Noble metal coated tips are produced with flat and circular tip front. The unusual truncated-cone tip shape is obtained by…
R. G. Agostino, M. P. De Santo, G. Liberti et al.Feb 10, 1999
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Anomalous magnetoconductance due to weak localization in 2D systems with anisotropic scattering: computer simulation
The results of computer simulation of particle motion over the plane with randomly distributed scatters are presented. They are used to analyse the influence of scattering anisotropy on the negative…
A. V. Germanenko, V. A. Larionova, G. M. Minkov et al.Feb 10, 1999
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High-temperature superconductivity in doped antiferromagnets
In the context of an effective model for doped antiferromagnets, whereby the charge carriers are treated as hard-core bosons, we demonstrate that the ground state energy close to half-filling is an…
Gregory C. PsaltakisFeb 9, 1999
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A note on the proof of magnetic flux quantization from ODLRO
It is noticed that the excellent proof of the connection of magnetic flux quantization and off-diagonal long range order (ODLRO) presented recently by Nieh, Su and Zhao suffers from an imperfection,…
Feng Sze-Shiang, Zhu Dong-PeiFeb 9, 1999
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Dressed States of a two component Bose-Einstein Condensate
A condensate with two internal states coupled by external electromagnetic radiation, is described by coupled Gross Pitaevskii equations, whose eigenstates are analogous to the dressed states of…
P. B. Blakie, R. J. Ballagh, C. W. GardinerFeb 9, 1999
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Coherent Dynamics of Vortex Formation in Trapped Bose-Einstein Condensates
Simulations of a rotationally stirred condensate show that a regime of simple behaviour occurs in which a single vortex cycles in and out of the condensate. We present a simple quantitative model of…
B. M. Caradoc-Davies, R. J. Ballagh, K. BurnettFeb 8, 1999
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The effects of weak disorders on Quantum Hall critical points
We study the consequences of random mass, random scalar potential and random vector potential on the line of clean fixed points between integer/fractional quantum Hall states and an insulator. This…
Jinwu YeFeb 8, 1999
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η-Exponents in the one dimensional antiferromagnetic Heisenberg model with next to nearest neighbour coupling
We investigate the critical exponents η3(α,M), η1(α,M) associated with the singularities in the longitudinal and transverse structure factors of the one dimensional antiferromagnetic Heisenberg…
C. Gerhardt, A. Fledderjohann, E. Aysal et al.Feb 5, 1999
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Stochastic multiplicative processes with reset events
We study a stochastic multiplicative process with reset events. It is shown that the model develops a stationary power-law probability distribution for the relevant variable, whose exponent depends…
Susanna C. Manrubia, Damian H. ZanetteFeb 4, 1999
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Canonical Transformation Approach to the Ultrafast Non-linear Optical Dynamics of Semiconductors
We develop a theory describing the effects of many-particle Coulomb correlations on the coherent ultrafast nonlinear optical response of semiconductors and metals. Our approach is based on a mapping…
I. E. Perakis, T. V. ShahbazyanFeb 3, 1999
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Quantum versus Semiclassical Description of Selftrapping: Anharmonic Effects
Selftrapping has been traditionally studied on the assumption that quasiparticles interact with harmonic phonons and that this interaction is linear in the displacement of the phonon. To complement…
S. Raghavan, A. R. Bishop, V. M. KenkreFeb 3, 1999
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Metamagnetism in the XXZ model with next-to-nearest-neighbor coupling
We investigate groundstate energies and magnetization curves in the one dimensional XXZ-model with next to nearest neighbour coupling α>0 and anisotropy Δ (-1 Δ 1) at T=0. In between the…
C. Gerhardt, K. -H. Mütter, H. KrögerFeb 3, 1999
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The new line of attack of analyses of NMR in 2D structures
There was shown that Fourier transform of the negative magnetoresistance (NMR) which is due to interference correction to the conductivity contains the information about the area distribution…
G. M. Minkov, S. A. Negashev, O. E. Rut et al.Feb 3, 1999
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Statistical properties of genealogical trees
We analyse the statistical properties of genealogical trees in a neutral model of a closed population with sexual reproduction and non-overlapping generations. By reconstructing the genealogy of an…
Bernard Derrida, Susanna C. Manrubia, Damian H. ZanetteFeb 2, 1999
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Initial-Value Problem for Inhomogeneous Condensate: Gaussian Approximation and Beyond
Using many-body theory we develop a set of formally exact kinetic equations for inhomogeneous condensate and one-body observables. The method is illutrated for phi4 field theory in 1+1 dimensions.…
Chi-Yong Lin, A. F. R. de Toledo PizaFeb 2, 1999
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Reply to Comment on "Theory of Spinodal Decomposition"
Rutenberg [cond-mat/9411016] claimed erroneously that I incorrectly apply only global conservation constraint to systems with local conservation embodied by continuity equation [PRL vol.72, p.1850…
S. B. GoryachevFeb 2, 1999
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Size-dependent Correlation Effects in Ultrafast Optical Dynamics of Metal Nanoparticles
We study the role of collective surface excitations in the electron relaxation in small metal particles. We show that the dynamically screened electron-electron interaction in a nanoparticle contains…
T. V. Shahbazyan, I. E. PerakisFeb 1, 1999
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Time evolution of near membrane layers
The near membrane layer is defined as a region where the concentration of the substance transported across the membrane drops k times. The time evolution of such a layer is studied experimentally…
Kazimierz Dworecki, Tadeusz Kosztolowicz, Slawomir Wasik et al.Feb 1, 1999
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The correlation length of the Heisenberg antiferromagnet with arbitrary spin S
Experiments and numerical data on the correlation length for large S disagree strongly with the theoretical prediction based on the effective field theory prescription of the magnon physics. The…
P. HasenfratzJan 30, 1999
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Acoustic radiation controls friction: Evidence from a spring-block experiment
Brittle failures of materials and earthquakes generate acoustic/seismic waves which lead to radiation damping feedbacks that should be introduced in the dynamical equations of crack motion. We…
Anders Johansen, Didier SornetteJan 29, 1999
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Can we Measure Superflow on Quenching He4?
Zurek has provided a simple picture for the onset of the lamda-transition in He4, not currently supported by vortex density experiments. However, we argue that the seemingly similar argument by Zurek…
E. Kavoussanaki, R. J. RiversJan 29, 1999
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Beyond Gross-Pitaevskii:local density vs. correlated basis approach for trapped bosons
We study the ground state of a system of Bose hard-spheres trapped in an isotropic harmonic potential to investigate the effect of the interatomic correlations and the accuracy of the…
A. Fabrocini, A. PollsJan 29, 1999
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Global versus local billiard level dynamics: The limits of universality
Level dynamics measurements have been performed in a Sinai microwave billiard as a function of a single length, as well as in rectangular billiards with randomly distributed disks as a function of…
M. Barth, U. Kuhl, H. -J. StoeckmannJan 27, 1999
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Spin-Imbalance and Magnetoresistance in Ferromagnet/Superconductor/Ferromagnet Double Tunnel Junctions
We theoretically study the spin-dependent transport in a ferromagnet/super- conductor/ferromagnet double tunnel junction. The tunneling current in the antiferromagnetic alignment of the…
S. Takahashi, H. Imamura, S. MaekawaJan 27, 1999
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