Engineering topological materials—one layer of atoms at a time

Matthew Brahlek, Materials Institute, Penn. State University.

The unusual, Dirac-like electronic states that emerge on the surface of topological insulator (TIs) are of wide interest for both fundamental studies as well as a range of practical applications. Despite the theoretical beauty, defects in real materials mask these interesting properties. Here, I will focus on how the atomic-scale control of molecular beam epitaxy, which is the gold-standard for synthesizing the highest quality materials, opens up pathways to control defects thus enabling the exploration of the intrinsic properties in TIs. In particular, I will discuss the limits from the ultra-clean, where the surface-states can be either coupled or decoupled, to the highly-disordered, where the notion of topological character breaks down.