331 research outputs found
Mutual influence of structural distortion and superconductivity in systems with degenerate bands
The interplay between the band Jahn-Teller distortion and the
superconductivity is studied for the system whose Fermi level lies in two-fold
degenerate band. Assuming that the lattice distortion is coupled to the orbital
electron density and the superconductivity arises due to BCS pairing mechanism
between the electrons, the phase diagram is obtained for different doping with
respect to half-filled band situation. The coexistence phase of
superconductivity and distortion occurs within limited range of doping and the
distortion lowers the superconducting transition temperature . In presence
of strong electron-lattice interaction the lattice strain is found to be
maximum at half-filling and superconductivity does not appear for low doping.
The maximum value of obtainable for an optimum doping is limited by the
structural transition temperature . The growth of distortion is arrested
with the onset of superconductivity and the distortion is found to disappear at
lower temperature for some hole density. Such arresting of the growth of
distortion at produces discontinuous jump in thermal expansion
coefficient. The variation of strain with temperature as well as with doping,
thermal expansion coefficient, the vs behaviour are in
qualitative agreement with recent experimental observations on interplay of
distortion and superconductivity in cuprates.Comment: 15 pages Revtex style, 9 figures available on request to first Autho
Large-eddy simulation of the lid-driven cubic cavity flow by the spectral element method
This paper presents the large-eddy simulation of the lid-driven cubic cavity
flow by the spectral element method (SEM) using the dynamic model. Two spectral
filtering techniques suitable for these simulations have been implemented.
Numerical results for Reynolds number are showing very good
agreement with other experimental and DNS results found in the literature
Optically opaque color-flavor locked phase inside compact stars
The contribution of thermally excited electron-positron pairs to the bulk
properties of the color-flavor locked quark phase inside compact stars is
examined. The presence of these pairs causes the photon mean free path to be
much smaller than a typical core radius ( km) for all
temperatures above 25 keV so that the photon contribution to the thermal
conductivity is much smaller than that of the Nambu-Goldstone bosons. We also
find that the electrons and positrons dominate the electrical conductivity,
while their contributions to the total thermal energy is negligible.Comment: 3 pages, 2 figures. Published versio
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