Ternary Tetradymite Compounds as Topological Insulators

TL;DR

This paper identifies ternary tetradymite compounds as stable topological insulators with unique surface states and potential for electronic applications, using theoretical analysis of their electronic structures and surface properties.

Contribution

It demonstrates that Bi2Se2Te and related compounds are stable topological insulators with tunable surface states, expanding the class of materials suitable for topological electronics.

Findings

Bi2Se2Te is a promising candidate for studying massive Dirac Fermions.

Bi2Te2S offers high bulk resistivity suitable for device applications.

Surface Dirac point in Bi2Se2Te is isolated in the bulk band gap.

Abstract

Ternary tetradymites Bi2Te2S, Bi2Te2Se and Bi2Se2Te are found to be stable, bulk topological insulators via theory, showing band inversion between group V and VI pz orbitals. We identify Bi2Se2Te as a good candidate to study massive Dirac Fermions, with a (111) cleavage-surface-derived Dirac point (DP) isolated in the bulk band gap at the Fermi energy Ef like Bi2Se3 but with a spin texture alterable by layer chemistry. In contrast, Bi2Te2S and Bi2Te2Se (111) behave like Bi2Te3, with a DP below Ef buried in bulk bands. Bi2Te2S offers large bulk resistivity needed for devices.