Generic H-T phase diagram of a staggered-Rashba superconductor

Superconductivity in a crystal lacking inversion exhibits complex (Rashba) spin-orbit-coupling effects, resulting in mixed-parity pairing and an unusual magnetic response. In our work, we study the generic phase diagram of a layered, globally centrosymmetric superconductor with alternating Rashba spin-orbit coupling in the stacking of layers within a generalized Ginzburg-Landau model. The superconducting order parameter (locally) mixes even- and an odd-parity pairing components, which exchange their roles as dominant pairing channel upon increasing the magnetic field. As a consequence, the upper critical field exhibits an unusual kink feature. Furthermore, the associated phase transition within the mixed phase is of first order and, due to the local mixing of even- and odd-parity components, is stable against splitting into two second-order transitions. The resulting generic phase diagram qualitatively agrees with the recently found H-T phase diagram of the heavy-fermion superconductor CeRh₂As₂ and emphasizes the role of local inversion-symmetry breaking in this compound.