What can defect bound states tell us? A case study of superconducting LiFeAs

Condensed Matter Seminars

Speaker: Shun Chi, Department of Physics & Astronomy, UBC
Date & Time: February 6, 2017 1:00 - 2:00
Location: AMPEL 311
Local Contact: Doug Bonn
Intended Audience: Graduate

Defect physics is one the driving forces required to understand the mechanism of superconductivity. In conventional s-wave superconductors, only magnetic defects (impurities) exhibit impurity bound states, whereas for a sign-change order parameter they can occur for both magnetic and nonmagnetic defects. Impurity bound states in superconductors can thus provide important insight into the order parameter. Here, I will present combined experimental and theoretical studies of defect bound states in superconducting LiFeAs, one member in the high-Tc, iron-based class of superconductors. Scanning tunneling microscopy is employed to probe local defect physics. A detailed comparison between experimental data and theoretical simulations of quasiparticle interference reveals the order parameter of LiFeAs, as well as the nature of the defects.