Temperature dependence of angle-resolved photoemission of the crystalline topological insulator Pb$_{1-x}$Sn$_x$Se(111)

The system Pb$_{1-x}$Sn$_x$Se is a topological insulator protected by mirror symmetry. Angle-resolved photoemission investigations have so far been concentrating on (100) surfaces of bulk single crystals. Here, we systematically study (111) epitaxial films under variation of the Sn concentration (10%, 20% and 28%) and temperature (300–30 K). We report the behavior of Dirac cones at $\overline{\Gamma}$ and $\overline{M}$ points of the surface Brillouin zone across the temperature-induced topological phase transition.