Spin texture and spin-orbit coupling contributions in spin-triplet superconductivity

Abstract

Over the past decade, it has been proposed theoretically and confirmed experimentally that long-range spin-triplet (LRT) superconductivity can be generated in superconductor/ferromagnet hybrids either by the presence of spin textures (ST-LRT) or owing to spin-orbit coupling (SOC-LRT). Nevertheless, there has been no theoretical or experimental investigation to date suggesting that both contributions could simultaneously exist within an experimental system. To disentangle these contributions, we present a comprehensive study of superconducting quasiparticle interference effects taking place inside a ferromagnetic layer interfacing a superconductor, through the investigation of above-gap conductance anomalies (CAs) related to MacMillan-Rowell resonances. The bias dependence of the CAs has been studied under a wide range of in-plane (IP) and out-of-plane (OOP) magnetic fields in two types of epitaxial, V/MgO/Fe-based ferromagnet-superconductor junctions with interfacial spin-orbit coupling. We observe an anisotropy of the CA amplitude under small IP and OOP magnetic fields while remaining weakly affected by high fields, and implement micromagnetic simulations to help us distinguish between the ST-LRT and SOC-LRT contributions. Our findings suggest that further exploration of Fabry-Pérot-type interference effects in electron transport could yield valuable insights into the hybridization between superconductors and ferromagnets induced by spin-orbit coupling and spin textures.

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