Chiral Superconductivity in Heavy-Fermion Metal UTe2
Lin Jiao, Sean Howard
Spin-triplet superconductivity is a condensate of electron pairs with spin-1 and an odd parity pair wavefunction1. A particularly interesting manifestation of triplet pairing is a chiral p-wave state which is topologically non-trivial and a natural platform for realizing Majorana edge modes2,3. Triplet pairing is however rare in solid state systems and so far, no unambiguous identification has been made in any bulk compound. Since pairing is most naturally mediated by ferromagnetic spin fluctuations, uranium based heavy fermion systems containing felectron elements that can harbor both strong correlations and magnetism are considered ideal candidate spin-triplet superconductors4-10. In this work we present scanning tunneling microscopy (STM) studies of the newly discovered heavy fermion superconductor, UTe2 with a TSC of 1.6 K11. We find signatures of coexisting Kondo effect and superconductivity which show competing spatial modulations within one unit-cell. STM spectroscopy at step edges oriented at 0 °- and 45 ° with respect to the a-axis show signatures of chiral in-gap states, predicted to exist on the boundary of a topological superconductor, which have not been observed to date. Combined with existing data indicating triplet pairing, the presence of chiral edge states suggests that UTe2 is a strong candidate material for chiral-triplet topological superconductivity.