Nontrivial spin-texture of the surface states in topological crystalline insulator SnTe

We present a first principles investigation of the nontrivial surface states and their spin-texture in the topological crystalline insulator SnTe[1,2]. The surface state dispersion on the [001] surface is found to support four Dirac-cones centered along the intersection of the mirror plane and the surface plane. The in-plane spin-texture displays helicity and indicates a nontrivial mirror Chern number of -2, distinct from that of -1 in a Z$_{2}$ topological insulator such as Bi/Sb. The surface state dispersion and the associated spin-texture are shown to provide an experimental route for determining the presence of a nontrivial Chern number. Work supported by the US DOE.\\ \mbox{[1]} T. H. Hsieh \textit{et al.}, Nature Commun. {\bf 3}, 982 (2012).\\ \mbox{[2]} S. Y. Xu \textit{et al.}, Nature Commun. (2012 in press). Preprint at http://arXiv.org/abs/1210.2917.