Proximity effects in nanostructures with geometric curvature for superconducting spintronics

Abstract

This thesis explores new avenues for the field of superconducting spintronics, with a focus on hybrid structures of superconductors and geometrically curved magnetic materials. In these structures the proximity effect induces superconducting correlations in the magnetic material and we study how these correlations are influenced by geometric curvature and magnetic properties. We perform theoretical and numerical investigations to show that geometric curvature induces many interesting effects in superconducting-magnetic heterostructures, and we discuss how these effects could be exploited in new device designs for superconducting spintronics applications. Among these effects, we show that geometric curvature induces long-range supercurrents and a tunable 0-π transition in superconductor-curved ferromagnet-superconductor junctions, which means the curvature can control the direction of charge current flow. Moreover, we demonstrate how geometric curvature produces a superconducting spin-valve effect in hybrid structures of superconductors and curved ferromagnets, where the critical temperature of the system can be controlled by varying the curvature. In the context of the interplay between superconductivity and magnetism, we present a mechanism producing superconductivity in high magnetic field in multiband superconductors. Finally, we introduce a diffusive theory allowing to include geometric curvature in superconducting-antiferromagnetic heterostructures, and give a numerical analysis of observables of diffusive superconductivity in antiferromagnetic helix hybrid nanowires.