Metallic Surface State of Correlated Topological Insulator

SmB₆ has been studied for a number of years and its observed behavior had presented investigators with a conflicting set of observations that resisted explanation until recently. The observation of quantum oscillations by Li et. al. in what is a bulk insulator confirm that SmB₆ becomes a topological insulator at low temperatures. A topological insulator is a material that develops a unique quantum mechanical state on its surface, which allows electrons to flow in a fashion similar to a metal.