Curvature control of the superconducting proximity effect in diffusive ferromagnetic nanowires
Tancredi Salamone, Henning G. Hugdal, Morten Amundsen, Sol H. Jacobsen
Abstract
Coupling a conventional $s$-wave superconductor to a ferromagnet allows us, via the proximity effect, to generate superconducting triplet correlations. This feature can be employed to achieve a superconducting triplet spin-valve effect in superconductor-ferromagnet (SF) hybrid structures, for example by switching the magnetizations of the ferromagnets between parallel and antiparallel configurations in ${\text{F}}_{1}{\text{SF}}_{2}$ and ${\mathrm{SF}}_{1}{\mathrm{F}}_{2}$ trilayers, or in SF bilayers with both Rashba and Dresselhaus spin-orbit coupling (SOC). It was recently reported that geometric curvature can control the generation of long-ranged triplets. We use this property to show that the superconducting critical temperature of an SF hybrid nanowire can be tuned by varying the curvature of the ferromagnetic side alone, with no need of another ferromagnet or SOC. We show that the variation of the critical temperature as a function of the curvature can be exploited to obtain a robust, curvature-controlled, superconducting triplet spin-valve effect. Furthermore, we perform an analysis with the inclusion of spin-orbit coupling and explain how it modifies the spin-valve effect both quantitatively and qualitatively.