Proximity effect sandwiches containing local spin fluctuations

Abstract

A proximity effect sandwich that contains local spin fluctuations in the normal layer is studied. The renormalization group approach is used to treat the Coulomb repulsion between the d electrons of opposite spins that are localized on the transition metal impurities present in the normal layer. The perturbations due to the tunneling of electrons from one layer to the other and the mixing of the normal-layer electrons with the impurity d electrons are treated using the standard Born approximation. A decrease of the transition temperature for both thin and thick, superconducting layers is obtained. It is found that there is a critical concentration at which the superconductivity in the thin superconducting layer can be quenched. For the thick-superconducting-layer sandwiches, no critical concentration is found. © 1984 Plenum Publishing Corporation.