Candidates for topological insulators: Pb-based chalcogenide series

Abstract

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, and the topological phases are changed from a topological insulator to a band insulator with increasing $n$. Among the new topological insulators, we found a large bulk band gap of 0.40 eV in PbBi${}_{2}$Se${}_{4}$, and that of Pb${}_{2}$Sb${}_{2}$Te${}_{5}$ is located near the phase boundary between a trivial and a nontrivial topological insulator, which raises the possibility of tuning the topological phase by changing the external parameters.