Speaker
Description
The heavy-fermion compound UTe2 is a candidate for hosting intrinsic spin-triplet superconductivity. At present, however, the type of triplet Cooper pairing realized in UTe2 remains unknown, which calls for further experimental and theoretical investigations. In this talk, I present a microscopic minimal model for the superconducting phases of UTe2 based on recent findings in the description of its low-energy normal state electronic properties. I apply the resulting theoretical model to extract the nodal gap properties of the allowed superconducting ground states, and deter-mine their associated topological surface states on the experimentally relevant (0-11) cleave plane.
It is found that the Fermi surface of UTe2 enforces additional point nodes in excess to the point nodes imposed by symmetry, which may reconcile several experiments seemingly in conflict with B2u or B3u pairing symmetries. Furthermore, we map out the in-gap Majorana surface-bound modes exist-ing on the (0-11) surface, and discuss their potential for additional insight into the pairing structure of UTe2. Quasiparticle interference (QPI) obtained from scanning tunneling microscopy (STM) is a pow-erful method to help extract the pairing symmetry of unconventional superconductors. We apply the model for UTe2 to compute its QPI signals and compare the resulting QPI with recent STM measurements. We conclude that the two candidate Cooper pair instabilities B2u and B3u exhibit distinct features in the QPI intensity to discriminate these using the experimental data. Characteristic features of the emergent topological surface states protected by mirror symmetries provide further unique signatures to help pinpointing the pairing symmetry channel of UTe2. I will discuss to what extent experimental STM results are in agreement with various proposed pairing states of UTe2.