2002/11/30 by R. Micnas
Physics and Astronomy · #cond-mat.supr-con #cond-mat.str-el
published as Acta Physica Polonica A100(s), 177-194 (2001) · 23 pages, 2 figures
arxiv created 2003/05/29 · arxiv updated 2009/11/30
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.