Probing the degree of spin polarization of a ferromagnet with ferromagnet/superconductor proximity effect

TL;DR

This study investigates how the superconducting transition temperature in Pb/Co2Cr1-xFexAl bilayers varies with ferromagnet spin polarization, revealing a correlation between superconductivity suppression and ferromagnetic spin polarization.

Contribution

It demonstrates a method to probe the spin polarization degree of a ferromagnet using the superconductor/ferromagnet proximity effect in bilayers.

Findings

Superconducting transition temperature depends on ferromagnet spin polarization.

Higher spin polarization correlates with greater suppression of superconductivity.

The approach provides a way to measure ferromagnetic spin polarization.

Abstract

Superconductor/ferromagnet proximity effect has been studied for Pb/Co$_2$Cr$_{1-x}$Fe$_x$Al bilayers. Different substrate temperatures allowed us to prepare the Heusler alloy Co$_2$Cr$_{1-x}$Fe$_x$Al films with different degree of spin polarization of conduction band of the Heusler layer. We obtain a strong correlation between the dependence of the superconducting transition temperature on the Pb-layer thickness at fixed thickness of the Heusler layer and the degree of spin polarization in the ferromagnetic layer.