Institute Colloquium: Vidya Madhavan (Univ. of Illinois Urbana-Champaign)

Chiral edge modes in the heavy fermion superconductor UTe2

Topological superconductors represent a fundamentally new phase of matter. Similar to topological insulators, the non-trivial topological characteristics of a topological superconductor dictate the presence of a topological edge states composed of Bogoliubov quasiparticles which live inside and span the superconducting gap. The intense interest in these materials stems from the fact that Bogoliubov excitations inside the gap of a topological superconductor are predicted to have all the characteristics of Majorana Fermions. A chiral p-wave superconductor which is topologically non-trivial is a natural platform for realizing these Majorana modes. In this talk I present scanning tunneling microscopy (STM) data on the newly discovered heavy fermion superconductor, UTe2 with a TC of 1.6K. I will show signatures of coexisting Kondo effect and superconductivity which show competing spatial modulations within one unit-cell.  STM spectroscopy at step edges show signatures of chiral in-gap states, predicted to exist at the boundaries of a topological superconductor. 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.