Proximity Effect Enhancement Induced by Roughness of SN Interface

Abstract

Critical temperature reduction $ΔT_c$ is considered for a thin film of a layered superconductor (S) with a rough surface covered by a thick layer of a normal metal (N). The roughness of the SN interface increases the penetration of electrons from the normal metal into the superconductor and leads to an enhancement of the proximity effect. The value of $ΔT_c$ induced by the roughness of the SN interface can be much higher than $ΔT_c$ for a film with a plain surface for an extremely anisotropic layered superconductor with the coherence lengths $ξ_a,ξ_b\ggξ_c$.