Spin-orbital hallmarks of unconventional superconductors without inversion symmetry

The spin-orbital polarization of superconducting excitations in momentum space is shown to provide distinctive marks of unconventional pairing in the presence of inversion symmetry breaking. Taking the prototypical example of an electronic system with atomic spin-orbit and orbital-Rashba couplings, we provide a general description of the spin-orbital textures and their most striking changeover moving from the normal to the superconducting state. We find that the variation of the spin texture is strongly imprinted by the combination of the misalignment of spin-triplet d vector with the inversion asymmetry g-vector coupling and the occurrence of superconducting nodal excitations. Remarkably, the multiorbital character of the superconducting state allows us to unveil a unique type of topological transition for the spin winding around the nodal points. This finding indicates the fundamental topological relation between chiral and spin winding in nodal superconductors. By analogy between spin- and orbital-triplet pairing we point out how orbital polarization patterns can also be employed to assess the character of the superconducting state.