Expanding the operational temperature window of a superconducting spin valve

TL;DR

This paper demonstrates an expanded operational temperature window for superconducting spin valves by using tunable Heusler alloy layers, achieving a triplet spin-valve effect above 0.6 K and over 1 K temperature difference.

Contribution

It introduces a novel SSV structure with tunable ferromagnetic layers that enhances the triplet effect and operational temperature range.

Findings

Triplet spin-valve effect exceeds 1 K.

Operational temperature window up to 0.6 K.

Use of Heusler alloy layers for tunable magnetic properties.

Abstract

To increase the efficiency of the superconducting spin valve (SSV), special attention should be paid to the choice of ferromagnetic materials for the F1/F2/S SSV multilayer. Here, we report the preparation and the superconducting properties of the SSV heterostructures where Pb is used as the superconducting S layer. In the magnetic part of the structure, we use the same starting material, the Heusler alloy Co$_2$Cr$_{1-x}$Fe$_x$Al$_{y}$, for both F1 and F2 layers. We utilize the tunability of the magnetic properties of this alloy, which, depending on the deposition conditions, forms either an almost fully spin-polarized half-metallic F1 layer or a weakly ferromagnetic F2 layer. We demonstrate that the combination of the distinct properties of these two layers boosts the generation of the long-range triplet component of the superconducting condensate in the fabricated SSV structures and yields superior values of the triplet spin-valve effect of more than 1 K and of the operational temperature window of the SSV up to 0.6 K.