Superconducting Transition Temperature of Superconducting-Normal Periodic Multi-Layer

Abstract

Transition temperature T_c of superconducting-normal (S-N) periodic multi-layer system is studied in the clean limit. The finite reflection coefficient R at the interface is explicitlytaken into account. The obtained gap equation of S-N multi-layer israther compact and is similar to that of S-N double-layer. The behaviorof T_c of a periodic multi-layer qualitatively agrees with that ofthe corresponding double-layer except when the thickness of layer isshorter than the coherence length and R ~= 0.5 . Thicknessdependence of T_c of a periodic multi-layer is in good agreement withthe experimental data of Banerjee et al. on the Nb/Cu superlattice.