Bias current dependence of superconducting transition temperature in superconducting spin valve nanowires

Alejandro A. Jara; Evan Moen; Oriol T. Valls; Ilya N. Krivorotov

doi:10.1103/PhysRevB.100.184512

paper

Bias current dependence of superconducting transition temperature in superconducting spin valve nanowires

arXiv:1908.03612 · doi:10.1103/PhysRevB.100.184512

Abstract

Competition between superconducting and ferromagnetic ordering at interfaces between ferromagnets (F) and superconductors (S) gives rise to several proximity effects such as odd-triplet superconductivity and spin-polarized supercurrents. A prominent example of an S/F proximity effect is the spin switch effect (SSE) observed in S/F/N/F superconducting spin-valve multilayers, in which the superconducting transition temperature T $_{c}$ is controlled by the angle $ϕ$ between the magnetic moments of the F layers separated by a nonmagnetic metallic spacer N. Here we present an experimental study of SSE in Nb/Co/Cu/Co/CoO $_{x}$ nanowires measured as a function of bias current flowing in the plane of the layers. These measurements reveal an unexpected dependence of T $_{c} (ϕ)$ on the bias current: T $_{c} (π)$ --T $_{c} (0)$ changes sign with increasing current bias. We attribute the origin of this bias dependence of the SSE to a spin Hall current flowing perpendicular to the plane of the multilayer, which suppresses T $_{c}$ of the multilayer. The bias dependence of SSE can be important for hybrid F/S devices such as those used in cryogenic memory for superconducting computers as device dimensions are scaled down to the nanometer length scale.

arXiv comment6 pages, 3 figures

Bias current dependence of superconducting transition temperature in superconducting spin valve nanowires

Abstract

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