Coherence length in superconductors from weak to strong coupling
Abstract
We study the evolution of the superconducting coherence length from weak to strong coupling, both within a s-wave and a d-wave lattice model. We show that the identification of with the Cooper-pair size in the weak-coupling regime is meaningful only for a fully-gapped (e.g., s-wave) superconductor. Instead in the d-wave superconductor, where diverges, we show that is properly defined as the characteristic length scale for the correlation function of the modulus of the superconducting order parameter. The strong-coupling regime is quite intriguing, since the interplay between particle-particle and particle-hole channel is no more negligible. In the case of s-wave pairing, which allows for an analytical treatment, we show that is of order of the lattice spacing at finite densities. In the diluted regime diverges, recovering the behavior of the coherence length of a weakly interacting effective bosonic system. Similar results are expected to hold for d-wave superconductors.
Keywords
Cite
@article{arxiv.cond-mat/0109486,
title = {Coherence length in superconductors from weak to strong coupling},
author = {L. Benfatto and A. Toschi and S. Caprara and C. Castellani},
journal= {arXiv preprint arXiv:cond-mat/0109486},
year = {2009}
}
Comments
11 pages, 5 figures. Two appendices and new references added