Magnetic response and topology of a staggered-Rashba superconductor

The presence or absence of a center of inversion is a standard classifying property of superconducting materials: If the system possesses inversion, spin-singlet and spin-triplet order parameters are distinct by symmetry and can be distinguished experimentally through their magnetic response. In non-centrosymmetric systems, on the other hand, the two order parameters can mix and the magnetic response is inconclusive. Still, since a dominant spin-triplet order parameter can be a topological superconductor, it can be identified through its edge states. In our work, we examine the situation, where inversion is broken locally in a sublattice, but retained globally. In particular, we investigate the magnetic response and possible topological superconducting states for a system consisting of layers with alternating Rashba spin-orbit coupling in the z direction and focus on the situation of large spin-orbit coupling. In this case, the system shows signs of non-centrosymmetricity even for sizable hopping in the z direction, in other words in the three-dimensional limit. This opens the way to design new types of superconducting order parameters which are robust against magnetism.