Theory of proximity-effect sandwiches with magnetic impurities

Abstract

We extend the theory of proximity-effect sandwiches consisting of a thin normal ($N$) metal in perfect planar contact with a thick superconducting ($S$) metal to the case in which the $N$ metal contains magnetic as well as nonmagnetic impurities. We consider dilute concentrations of antiferromagnetic impurities, adapting the theory of Zittartz, Bringer, and M\"uller-Hartmann for magnetic impurities in superconductors to proximity systems. We discuss the influences of Kondo-effect impurities in this proximity system. We compare our theory with the experimental results of Dumoulin, Guyon, and Nedellec, and suggest possible cases in which new phenomena, such as the presence of three gaps in the density of states, might be observed.