Quasiparticle Interference of Spin-Triplet Superconductors: Application to UTe₂

Quasiparticle interference (QPI) obtained from scanning tunneling microscopy (STM) is a powerful method to help extract the pairing symmetry of unconventional superconductors. We examine the general properties of QPI on surfaces of spin-triplet superconductors. It is shown how the multi-component nature of the spin-triplet d-vector, and the general existence of topological surface states in triplet condensates, both offer important differences from QPI on spin-singlet superconductors. We then turn to a microscopic model relevant for the spin-triplet candidate UTe₂, compare the computed QPI with recent STM measurements and propose signatures for the direction of the d-vector phase-resolved QPI data. Characteristic features of the emergent topological surface states protected by chiral symmetry in general, and by mirror symmetries in the case of UTe₂, provide further guidance to pinpoint the superconducting state and exclude effects of the lower symmetry on the surface of the material.