Candidates for topological insulators: Pb-based chalcogenide series

摘要: Here, we theoretically predict that the series of Pb-based layered chalcogenides, Pb$_n$Bi$_2$Se$_{n+3}$ and Pb$_n$Sb$_2$Te$_{n+3}$, are possible new candidates for topological insulators. As $n$ increases, phase transition from a insulator to band is found occur between $n=2$ 3 both series. Significantly, among insulators, bulk gap 0.40eV in PbBi$_2$Se$_4$ which one largest Pb$_2$Sb$_2$Te$_5$ located immediate vicinity boundary, making its easily tunable by changing external parameters such as lattice constants. Due three-dimensional Dirac cone at massless fermions also may be accessible Pb$_2$Sb$_2$Te$_5$.