English

Coherence length in superconductors from weak to strong coupling

Superconductivity 2009-11-07 v2 Statistical Mechanics

Abstract

We study the evolution of the superconducting coherence length ξ0\xi_0 from weak to strong coupling, both within a s-wave and a d-wave lattice model. We show that the identification of ξ0\xi_0 with the Cooper-pair size ξpair\xi_{pair} in the weak-coupling regime is meaningful only for a fully-gapped (e.g., s-wave) superconductor. Instead in the d-wave superconductor, where ξpair\xi_{pair} diverges, we show that ξ0\xi_0 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 ξ0\xi_0 is of order of the lattice spacing at finite densities. In the diluted regime ξ0\xi_0 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

R2 v1 2026-07-22T10:27:56.679Z