Colloquium: Spin-orbit effects in superconducting hybrid structures

Spin-orbit coupling (SOC) describes the interaction between an electron's motion and its spin, and is ubiquitous in condensed matter systems. The interplay of SOC with superconductivity has attracted significant interest over the past decade and understanding has substantially progressed, both experimentally and theoretically. Even with well-understood materials, conventional $s$-wave superconducting hybrid structures with SOC provide a platform for realizing exotic phenomena and counterparts in the normal state. Understanding the emergent phenomena in such systems is an important aim in condensed matter physics. One such area relates to the generation and interplay of spin-polarized spin-triplet Cooper pairs in superconducting structures with magnetic interfaces. It is established that certain forms of magnetic inhomogeneity at an $s$-wave superconductor interface with a ferromagnet can transform spin-singlet Cooper pairs into a spin-polarized spin-triplet Cooper pairs, enabling transformative concepts for cryogenic computing. Recently, theory and experiments have demonstrated singlet-to-triplet pair conversion via SOC in $s$-wave superconducting structures with or without magnetic layers. Moreover, the spin-dependent properties of quasiparticles and their non-equilibrium behavior also change in the presence of SOC. These breakthroughs create the potential for energy-efficient control of static and dynamic spin phenomena in superconducting structures and devices. This article reviews progress in superconducting spintronics with a focus on the coupling of superconductivity and SOC in hybrid structures and devices, and outlines directions that are critical for future device development and fundamental understanding.Comment: 34 pages, 14 figure