New Candidates for Topological Insulators : Pb-based chalcogenide series

Hosub Jin; Jung-Hwan Song; Arthur J. Freeman; Mercouri G. Kanatzidis

doi:10.1103/PhysRevB.83.041202

paper

New Candidates for Topological Insulators : Pb-based chalcogenide series

arXiv:1007.5480 · doi:10.1103/PhysRevB.83.041202

Abstract

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, the phase transition from a topological insulator to a band insulator is found to occur between $n = 2$ and 3 for both series. Significantly, among the new topological insulators, we found a bulk band gap of 0.40eV in PbBi $_{2}$ Se $_{4}$ which is one of the largest gap topological insulators, and that Pb $_{2}$ Sb $_{2}$ Te $_{5}$ is located in the immediate vicinity of the topological phase boundary, making its topological phase easily tunable by changing external parameters such as lattice constants. Due to the three-dimensional Dirac cone at the phase boundary, massless Dirac fermions also may be easily accessible in Pb $_{2}$ Sb $_{2}$ Te $_{5}$ .