We have performed angle-resolved photoemission spectroscopy on the strongly spin-orbit coupled low-carrier density superconductor ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te}$ ($x=0.045$) to elucidate the electronic states relevant to the possible occurrence of topological superconductivity, as recently reported for this compound based on point-contact spectroscopy. The obtained energy-band structure reveals a small holelike Fermi surface centered at the $L$ point of the bulk Brillouin zone, together with a signature of a topological surface state, indicating that this material is a doped topological crystalline insulator characterized by band inversion and mirror symmetry. A comparison of the electronic states with a band-noninverted superconductor possessing a similar Fermi surface structure, ${\mathrm{Pb}}_{1-x}{\mathrm{Tl}}_x\mathrm{Te}$, suggests that the anomalous behavior in the superconducting state of ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te}$ is related to the peculiar orbital characteristics of the bulk valence band and/or the presence of a topological surface state.

• Received 24 December 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.206804