Ternary thallium-based semimetal chalcogenides Tl-V-VI2 as a new class of three-dimensional topological insulators

The results of the theoretical investigation of the bulk and surface electronic structures of Tl-V-VI2 compounds, where V is the Bi or Sb semimetal and VI is the Se or Te chalcogen, are reported. It has been shown that these compounds are three-dimensional topological insulators. Both a topologically protected surface state, which forms a Dirac cone at the Γ point, and occupied surface states, which are localized in the band gap, are present on the surface of these compounds.