Superconducting proximity effect in a diffusive ferromagnet with spin-active interfaces

TL;DR

This paper investigates how spin-active interfaces influence the superconducting proximity effect in diffusive ferromagnets, revealing significant impacts on the density of states and supercurrents, with experimental signatures identified.

Contribution

It introduces the phase-shifting conductance Gphi in boundary conditions, highlighting its strong effect on superconducting/ferromagnetic hybrid circuits.

Findings

Gphi significantly alters the density of states.

Gphi affects supercurrent predictions.

Experimental signatures of Gphi are identified.

Abstract

We reconsider the problem of the superconducting proximity effect in a diffusive ferromagnet bounded by tunneling interfaces, using spin-dependent boundary conditions. This introduces for each interface a phase-shifting conductance Gphi which results from the spin dependence of the phase shifts acquired by the electrons upon scattering on the interface. We show that Gphi strongly affects the density of states and supercurrents predicted for superconducting/ferromagnetic hybrid circuits. We show the relevance of this effect by identifying clear signatures of Gphi in the data of T. Kontos et al [Phys. Rev. Lett. 86, 304 (2001), ibid. 89, 137007 (2002)].