Angular Dependence of the Superconducting Transition Temperature in Ferromagnet-Superconductor-Ferromagnet Trilayers

TL;DR

This study investigates how the superconducting transition temperature in CuNi/Nb/CuNi trilayers varies with the angle between ferromagnetic layers, confirming theoretical predictions about triplet superconductivity in non-collinear magnetic configurations.

Contribution

It provides experimental evidence of angular dependence of $T_c$ in F/S/F trilayers, supporting proximity theory involving odd triplet components for non-collinear magnetizations.

Findings

$T_c$ varies with the angle between magnetic moments.

Qualitative agreement with F/S proximity theory.

Supports existence of odd triplet condensate component.

Abstract

The superconducting transition temperature, $T_c$, of a ferromagnet (F) - superconductor (S) - ferromagnet trilayer depends on the mutual orientation of the magnetic moments of the F layers. This effect has been previously observed in F/S/F systems as a $T_c$ difference between parallel and antiparallel configurations of the F layers. Here we report measurements of $T_c$ in CuNi/Nb/CuNi trilayers as a function of the angle between the magnetic moments of the CuNi ferromagnets. The observed angular dependence of $T_c$ is in qualitative agreement with a F/S proximity theory that accounts for the odd triplet component of the condensate predicted to arise for non-collinear orientation of the magnetic moments of the F layers.