Majorana multipole response with magnetic point group symmetry

The identification of Cooper pair symmetry is a crucial initial step in the study of topological superconductors (TSCs). Here, the authors develop a theory for the identification of pairing symmetry in time reversal symmetry breaking TSCs, focusing on the electromagnetic responses of Majorana fermions at their surfaces. They explore how the pairing symmetries relate to the electromagnetic response of the Majorana fermions under magnetic point group symmetry. The study also predicts the appearance of a magnetic quadrupole response in odd-parity chiral superconductivity in UTe${}_{2}$ and ferromagnetic superconductivity in UCoGe.