Tunability of thek-space location of the Dirac cones in the topological crystalline insulator Pb1−xSnxTe

Abstract

We have performed systematic angle-resolved photoemission spectroscopy of the topological crystalline insulator (TCI) Pb${}_{1\ensuremath{-}x}$Sn${}_{x}$Te to elucidate the evolution of its electronic states across the topological phase transition. As previously reported, the band structure of SnTe ($x=1.0$) measured on the (001) surface possesses a pair of Dirac-cone surface states located symmetrically across the $\overline{X}$ point in the (110) mirror plane. Upon approaching the topological phase transition into the trivial phase at ${x}_{c}\ensuremath{\approx}0.25$, we discovered that Dirac cones gradually move toward the $\overline{X}$ point with its spectral weight gradually reduced with decreasing $x$. In samples with $x\ensuremath{\le}0.2$, the Dirac-cone surface state is completely gone, confirming the occurrence of the topological phase transition. Also, the evolution of the valence band feature is found to be consistent with the bulk band inversion taking place at ${x}_{c}$. The tunability of the location of the Dirac cones in the Brillouin zone would be useful for applications requiring Fermi-surface matching with other materials, such as spin injection.