Imaging the Surface States of a Strongly Correlated Topological Insulator

Presenter: Professor Jenny Hoffman, Harvard University

The prediction and subsequent discovery of topological band insulators with robust spin-polarized surface states has launched a new subfield of physics over the last decade. In the last few years it has been recognized that when topology is combined with strong electron-electron correlations, even more interesting and potentially useful states of matter can arise, such as new topological classifications, fractionalized states, and many-body localization that preserves the topology of the insulating state against thermal destruction. Here I will give a general introduction to topological materials, and show the first direct proof of a strongly correlated topological insulator. Using scanning tunneling microscopy to probe real and momentum space structure, our images of electrons scattering off atomic defects on the heavy fermion material SmB6 reveal the evolution of the insulating gap arising from strong interactions, and a surface state with Dirac point close to the chemical potential. Our observations present the first opportunity to explore a strongly correlated topological state of matter.