The remarkable discovery of superconductivity above 100K in a single atomic layer of FeSe (compared to the relatively mundane Tc=8K in bulk FeSe) prompts tremendous excitement and numerous pressing questions. What is the mechanism of the order-of-magnitude Tc enhancement in FeSe? What is the pairing symmetry? Could FeSe be a topological superconductor? What applications might one envision with such a 2D superconductor? Are there other interface superconductors just waiting to be discovered? I will review current experimental progress towards addressing these questions, then discuss our own growth (via molecular beam epitaxy) and imaging (via scanning tunneling microscopy) of single layer FeSe. We use quasiparticle interference to access the structure of filled and empty states, and to detect the emergence of a new electronic band slightly above the Fermi level. We use the amplitude of the scattering signal to explore the pairing symmetry.
Argonne Physics Division Colloquium Schedule