Pb5Bi24Se41: A new member of the homologous series forming topological insulator heterostructures

• We have synthesized a new member of the homologous series related to topological insulators.
• In this compound, a heterostructure of topological and ordinary insulators naturally forms.
• Resistivity anisotropy suggests an important role of hybridization of the topological states.
• This compound expands the tunability of the topological states via chemical means.

We have synthesized Pb5Bi24Se41, 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 Pb5Bi24Se41 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.

X-ray diffraction profiles taken on cleaved surfaces of single-crystal samples of the (PbSe)5(Bi2Se3)3m homologous series with various m values up to 4, which realizes topological insulator heterostructures. Schematic crystal structure of the new phase, m=4, is also shown.Figure optionsDownload as PowerPoint slide