Transition Temperature of Superconductor-Insulator Superlattices

Abstract

We have extended the theory of layered superconductors to describe superlattices in which layers of superconducting material consisting of M unit cells are separated by insulating layers that are N unit cells thick. An intercell pairing interaction is identified which controls the variation of T_c with M and N, and raises T_c from low to high temperatures. The M-dependence is traced back to a finite-size effect corresponding to crossover from nearly two- to three-dimensional behaviour.