Ferromagnet-superconductor proximity effect: The clean limit

TL;DR

This paper theoretically investigates how ferromagnetic metals affect a superconducting film in the clean limit, revealing that the pair potential remains stable while charge transport becomes spin polarized and sensitive to ferromagnetic properties.

Contribution

It provides a self-consistent analysis of the ferromagnet-superconductor proximity effect in the clean limit, highlighting the stability of the pair potential and the spin-polarized transport behavior.

Findings

Pair potential and critical temperature are weakly affected by exchange interaction.

Charge transport in thin films is spin polarized and depends on ferromagnetic strength.

Pair potential does not vanish for any finite superconducting layer thickness.

Abstract

We study theoretically the influence of ferromagnetic metals on a superconducting film in the clean limit. Using a self-consistent solution of the Bogoliubov--de Gennes equation for a ferromagnet-superconductor-ferromagnet double junction we calculate the pair potential and conductance spectra as a function of the superconducting layer thickness $d$ for different strengths of ferromagnets and interface transparencies. We find that the pair potential and the critical temperature are weakly perturbed by the exchange interaction and do not drop to zero for any finite $d$. On the other hand, for thin superconducting films charge transport is spin polarized and exhibits a significant dependence on the ferromagnetic strength and magnetization alignment.