Pb₅Bi₂₄Se₄₁: A New Member of the Homologous Series Forming Topological Insulator Heterostructures

We have synthesized Pb_{5}Bi_{24}Se_{41}, which is a new member of the (PbSe)_{5}(Bi2Se3)_{3m} homologous series with m = 4. This series of compounds consist of alternating layers of the topological insulator Bi2Se3 and the ordinary insulator PbSe. Such a naturally-formed heterostructure has recently been elucidated to give rise to peculiar quasi-two-dimensional topological states throughout the bulk, and the discovery of Pb_{5}Bi_{24}Se_{41} expands the tunability of the topological states in this interesting homologous series. The trend in the resistivity anisotropy in this homologous series suggests an important role of hybridization of the topological states in the out-of-plane transport.