Pair breaking in superconductors with strong spin-orbit coupling

We study the influence of symmetry-breaking perturbations on superconductivity in multiorbital materials, with a particular focus on an external magnetic field. We introduce the field-fitness function which characterizes the pair-breaking effects of the perturbation on a given superconducting state. For even-parity superconductors we find that this field-fitness function for an external magnetic field is one, implying that the paramagnetic response is controlled only by a generalized effective g factor. For odd-parity superconductors, the interplay of the effective g factor and the field-fitness function can lead to counterintuitive results. We demonstrate this for p-wave pairing in the effective j = 32 electronic states of the Luttinger-Kohn model.

Automated summary

We investigate the effect of symmetry-breaking perturbations on superconductivity in multiorbital materials, focusing on the influence of an external magnetic field. We introduce the field-fitness function to characterize the disruption of pair formation due to the perturbation. In even-parity superconductors, the field-fitness function for an external magnetic field is unity, indicating that the paramagnetic response is determined solely by a generalized effective g-factor. For odd-parity superconductors, the interplay between the effective g-factor and the field-fitness function can result in counterintuitive outcomes. We demonstrate this phenomenon in the p-wave pairing of the effective j=32 electronic states in the Luttinger-Kohn model.