Spin response and topology of a staggered-Rashba superconductor
Anastasiia Skurativska, Manfred Sigrist, Mark H. Fischer
Abstract
Inversion symmetry is a key symmetry in unconventional superconductors, and even its local breaking can have profound implications. For inversion-symmetric systems, there is a competition on a microscopic level between the spin-orbit coupling associated with the local lack of inversion and hybridizing terms that ``restore'' inversion. Investigating a layered system with alternating mirror-symmetry breaking, we study this competition considering the spin response of different superconducting order parameters for the case of strong spin-orbit coupling. We find that signatures of the local noncentrosymmetry, such as an increased spin susceptibility in spin-singlet superconductors for $T\ensuremath{\rightarrow}0$, persist even into the quasi-three-dimensional regime. This leads to a direction-dependent spin response that allows us to distinguish different superconducting order parameters. Furthermore, we identify several regimes with possible topological superconducting phases within a symmetry-indicator analysis. Our results may have direct relevance for the recently reported Ce-based superconductor ${\mathrm{CeRh}}_{2}{\mathrm{As}}_{2}$ and beyond.