On the Crossover from BCS Superconductivity to Bose Condensation

R. Micnas

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arXiv · cond-mat/0211561

On the Crossover from BCS Superconductivity to Bose Condensation

R. Micnas

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Abstract

We outline a microscopic approach to the superconducting fluctuations and pairing correlations in the attractive Hubbard model above Tc, using the functional integral method. A crossover from BCS superconductivity to Bose condensation of preformed pairs is studied by constructing the appropriate Ginzburg-Landau functionals. The differences between the lattice and the continuum models are discussed. The case of quasi-two-dimensional superconductors as well as the model with non-local pairing interaction are also examined. The effects of gaussian fluctuations of the order parameter are analyzed in the T-matrix approach, the self-consistent Hartree approach and finally within the Ginzburg-Landau theory. Simlarities with a paramagnon theory of itinerant-electron magnetism are pointed out.

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R. Micnas. 2003-05-29. On the Crossover from BCS Superconductivity to Bose Condensation. https://arxiv.org/abs/cond-mat/0211561

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