PROXIMITY EFFECT IN SUPERCONDUCTING LAYERED STRUCTURES

A general formalism for discussing the superconducting proximity effect and the charge-carrier transfer effect in an inhomogeneous layered structure has been obtained from the Gor'kov equation. Two practical systems, which are finite superconductor/nonsuperconductor multilayer and superlattice, are considered. The physical properties such as the transition temperature, the coherence length, the proximity effect, and the charge-carrier transfer effect have been discussed. When compared with experiment, our calculations show that the depression of the transition temperature in the c-oriented Y-Ba-Cu-O/Pr-Ba-Cu-O superlattices is dominantly induced by the proximity effect.