# Superconducting switching due to triplet component in the Pb/Cu/Ni/Cu/Co$_2$Cr$_{1-x}$Fe$_x$Al$_y$ spin-valve structure

## TL;DR

This study demonstrates a significant superconducting switching effect in a spin-valve structure caused by the long-range triplet component, with potential applications in superconducting spintronics.

## Contribution

It reveals the role of a half-metallic Heusler alloy in enhancing triplet superconductivity and switching effects in multilayer spin-valve structures.

## Key findings

- Superconducting transition temperature varies with magnetization angle, showing a deep minimum near perpendicular orientation.
- The observed switching effect is attributed to the long-range triplet component of the superconducting condensate.
- Large switching effects are achieved due to the half-metallic nature of the Heusler alloy layer.

## Abstract

We report the superconducting properties of the Co$_2$Cr$_{1-x}$Fe$_x$Al$_y$/Cu/Ni/Cu/Pb spin-valve structure which magnetic part comprises the Heusler alloy layer HA = Co$_2$Cr$_{1-x}$Fe$_x$Al$_y$ with a high degree of spin polarization (DSP) of the conduction band and the Ni layer of variable thickness. We obtained that the separation between the superconducting transition curves measured for the parallel ($\alpha = 0^\circ$) and perpendicular ($\alpha = 90^\circ$) orientation of the magnetizations of the HA and Ni layers reaches up to 0.5 K ($\alpha$ is an angle between the magnetization of two ferromagnetic layers). For all studied samples the dependence of the superconducting transition temperature $T_c$ on $\alpha$ demonstrates a deep minimum in the vicinity of the perpendicular configuration of magnetizations. This suggests that the observed minimum and the corresponding full switching effect of the spin valve is caused by the long-range triplet component of the superconducting condensate in the multilayer. Such a large effect can be attributed to a half-metallic nature of the HA layer which in the orthogonal configuration efficiently draws off the spin-polarized Cooper pairs from the space between the HA and Ni layers. Our results indicate a significant potential of the concept of the superconducting spin-valve multilayer comprising a half-metallic ferromagnet recently proposed by A. Singh et al., Phys. Rev. X 5, 021019 (2015) in achieving large values of the switching effect.