Evidence for Triplet Superconductivity in a Superconductor-Ferromagnet Spin Valve

TL;DR

This study provides experimental evidence for long-range triplet superconductivity in a superconductor-ferromagnet spin valve, showing a nonmonotonic dependence of the transition temperature on magnetization orientation.

Contribution

It demonstrates the direct observation of triplet superconductivity induced by noncollinear magnetizations in a spin valve system.

Findings

Superconducting transition temperature varies nonmonotonically with magnetization orientation.

Distinct minimum in transition temperature near orthogonal magnetization configuration.

Evidence supports the presence of long-range triplet superconductivity.

Abstract

We have studied the dependence of the superconducting (SC) transition temperature on the mutual orientation of magnetizations of Fe1 and Fe2 layers in the spin valve system CoO_x/Fe1/Cu/Fe2/Pb. We find that this dependence is nonmonotonic when passing from the parallel to the antiparallel case and reveals a distinct minimum near the orthogonal configuration. The analysis of the data in the framework of the SC triplet spin valve theory gives direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the two magnetizations.