Topological materials at the nanoscale

Professor Jennifer Hoffmann, Department of Physics
Harvard University, USA

Topological materials at the nanoscale

Once or twice per decade, the discovery of a new class of electronic materials takes the world by storm, generating thousands of scientific publications per year, and broad hopes for practical applications. In this category are the so-called “topological materials” – typically bulk insulators hosting topologically protected metallic surface states that have prompted numerous proposals for nanoscale devices. After an introduction to topological materials, I will describe efforts in my laboratory to measure their properties via low temperature scanning tunnelling microscopy. In the topological semimetal antimony (Sb), we study the effects of single-atom defects, we quantify parameters relevant to spintronics applications, and we establish new techniques for nanoscale electronic structure measurements. We further apply these techniques to SmB6, whose anomalous electronic properties have remained mysterious for almost 50 years, but may finally be explained as arising from a topological insulator with strong electron interactions.

Figure: Electron waves scattering off single atom impurities on the surface of topological antimony.