Abstract
We present a combined theoretical and experimental study of the electronic structure of stoichiometric , a natural superlattice of alternating quintuple layers and Bi bilayers. In contrast to the related semiconducting compounds and , density functional theory predicts is a semimetal. In this work, we compute the quasiparticle electronic structure of in the framework of the approximation within many-body perturbation theory. The quasiparticle corrections are found to modify the dispersion of the valence and conduction bands in the vicinity of the Fermi energy, leading to the opening of a small indirect band gap. Based on the analysis of the eigenstates, is classified as a dual topological insulator with bulk topological invariants and magnetic mirror Chern number . The bulk results are used to build a Wannier-function-based tight-binding Hamiltonian that is further applied to study the electronic properties of the (111) surface. The comparison with our angle-resolved photoemission measurements shows excellent agreement between the computed and measured surface states and indicates the dual topological nature of .
2 More- Received 12 November 2021
- Revised 9 February 2022
- Accepted 1 March 2022
DOI:https://doi.org/10.1103/PhysRevMaterials.6.034204
©2022 American Physical Society