Electronic band structure for occupied and unoccupied states of the natural topological superlattice phase Sb2Te

We present an experimental study describing the effects of surface termination on the electronic structure of the natural topological superlattice phase ${\mathrm{Sb}}_{2}\mathrm{Te}$. Using scanning angle-resolved photoemission microscopy, we consistently find various nonequivalent regions on the same surface after cleaving various ${\mathrm{Sb}}_{2}\mathrm{Te}$ single crystals. We were able to identify three distinct terminations characterized by different Sb/Te surface stoichiometric ratios and with clear differences in their band structure. For the dominating Te-rich termination, we also provide a direct observation of the excited electronic states and of their relaxation dynamics by means of time-resolved angle-resolved photoemission spectroscopy. Our results clearly indicate that the surface electronic structure is strongly affected by the bulk properties of the superlattice.