Strong-coupling corrections to the Bardeen-Cooper-Schrieffer ratios for a d-wave superconductor.

摘要: We have calculated, for a d-wave superconductor, the strong-coupling corrections to Bardeen-Cooper-Schrieffer (BCS) ratios: \ensuremath{\Delta}C(${\mathit{T}}_{\mathit{c}}$)/\ensuremath{\gamma}${\mathit{T}}_{\mathit{c}}$,2${\mathrm{\ensuremath{\Delta}}}_{0}$/${\mathit{T}}_{\mathit{c}}$,\ensuremath{\gamma}${\mathit{T}}_{\mathit{c}}^{2}$/${\mathit{H}}_{\mathit{c}}^{2}$(0), ${\mathit{h}}_{\mathit{c}}$(0) as well ratios normalized slope in specific-heat jump at ${\mathit{T}}_{\mathit{c}}$ and London penetration depth. used step-function approximation gap function considered an Einstein spectral density bosons. obtained terms up O(${\mathit{T}}_{\mathit{c}}^{4}$/${\mathrm{\ensuremath{\omega}}}_{\mathit{E}}^{4}$) (here ${\mathit{T}}_{\mathit{c}}$/${\mathrm{\ensuremath{\omega}}}_{\mathit{E}}$ is parameter ${\mathrm{\ensuremath{\omega}}}_{\mathit{E}}$ energy). While our results are approximate cases, weak-coupling exact. These no longer universal depend on considered. Our formulas also applicable some extended s-wave superconductors which basis with zero average over Fermi surface.