Department Colloquium | Andreev Reflection in Heavy Fermion Superconductors: Focus on CeCoIn5

Speaker: Laura Greene (University of Illinois-Urbana Champaign)

Andreev reflection, a retro-reflection of an incoming electron as a hole at a normal-metal/superconductor interface, is well understood in conventional superconductors; but for heavy-fermion superconductors (HFS), the consequences of the heavy electronic mass remain an open question. After an introduction to Andreev reflection and the “Rosetta Stone of HFS” CeCoIn5, data over a wide temperature and voltage range in three crystallographic orientations are presented. We show how this measurement is a spectroscopic probe of the symmetry of the order parameter. Furthermore, our observed Andreev signal and observed asymmetry in the background conductance can be accounted for by model based on two-fluid phenomenology and a Fano interference effect between two conductance channels.

This work is in collaboration with Wan Kyu Park, John L. Sarrao, and Joe N. Thompson.