1 research outputs found
BCS to Bose Crossover in Anisotropic Superconductors
In this work we use functional integral techniques to examine the nearest
neighbour attractive Hubbard model on a quasi-2D lattice. It is a simple
phenomenological model for the high-Tc cuprates that allows both extended
(non-local) s- and d-wave singlet superconductivity as well as mixed symmetry
states. The Hartree-Gor'kov mean field theory of the model has a finite
temperature phase diagram which shows a transition from pure s-wave to pure
d-wave superconductivity, via a mixed symmetry s+id state, as a function of
doping. Including Gaussian fluctuations we examine the crossover from
weak-coupling BCS superconductivity to the strong-coupling Bose-Einstein
condensation of composite s- or d-wave bosons and comment on the origin and
symmetry of the pseudogap.Comment: 20 pages inc. 13 figure