Condensed Matter Physics Seminar

Topological order is a new kind of collective order beyond Landau's symmetry-breaking classification. In this talk we will discuss a new type of 3D strongly correlated topological insulator phase in Kondo insulator material SmB6. We will present transport evidence for a highly conductive surface state surrounding a truly insulating bulk: At low temperature, we found that the Hall resistance scales with the surface, and is independent of the thickness. Using non-local transport measurements, we demonstrate that the electric conducting is mostly along the surface at low temperatures and zero magnetic field. The conductive surface seems to be robust against chemical etching and mechanical abrasion. And at sufficiently low temperature, we demonstrate that the surface conducting is partially quenched by a tiny magnetic field, which breaks time-reversal symmetry.