Topological Insulators
“zero-gap” Semiconductors
Theoretical predictions in novel material, like topological insulators, are also investigated by HAXPES. The comparison between HAXPES valence band spectra and ab initio calculations shows clear evidence of zero band gap states in C1b Heuslers: LuPdBi, PtYSb and PtLaBi. The zero band gap is resulted from the cubic symmetry and is a signature of band inversion, which is an essential feature for a topological insulator state [1][2].