Spin and magnetic properties of superconducting tunnel junctions

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Superconducting junctions exhibit fascinating physical phenomena while being essential for modern technology, especially for emerging quantum computing architectures. To allow for additional functionalities, researchers are exploring superconducting junctions comprising magnetic elements and tunnel regions with interfacial spin-orbit fields. The interplay of the two most important spin interactions---exchange and spin-orbit coupling---and the long-range superconducting coherence has already been demonstrated to have signatures in spectroscopy and transport, and is predicted to lead to topological superconductivity harboring Majorana states. We will explore theoretically ramifications of the interplay for multicomponent superconducting magnetic junctions, by performing systematic and comprehensive microscopic calculations of the spectroscopic features and electrical conductance for various classes of junctions, in close cooperation with experiment. The main directions of our studies include i) tunneling magnetoresistance Josephson effect, which involves magnetic bilayers encapsulated by superconducting electrodes, ii) noncollinear magnetic layers generating spin-polarized triplet supercurrents in adjacent superconductors, and iii) Andreev bound state spectroscopy in realistic device geometries.