Topological Insulators / Normal Insulators Superlattices

In 1970 Esaki and Tsui proposed a solid-state artificial structure: the superlattice. The recently discovered of topological insulator materials aroused the physics community. In this work, we investigate topological / normal insulator (TI/NI) interfaces and its superlattice using a combination of DFT and a highly accurate tight biding modeling [1]. The calculations were based on the Bi₂Se₃ topological insulator. The normal insulator in simply the Bi₂Se₃ without spin-orbit coupling. This approach enables us to investigate a chemically perfect TI/NI interface. Experimentally these superlattices have been reported by Belopolski et. al. [2]. Initially, we investigated a hypothetical infinity TI/NI superlattice and for a large NI thickness the topologically protected states are present. We also investigate when a TI (NI) is placed between two NI(TI) regions. We also show how to used these superllattices to supress the Bi₂Se₃ bulk states, which are detrimental to its transport properties. Finally we investigate the 1D chain of Dirac states proposed by Belopolski.

[1] L. A. Agapito, A. Ferretti, A. Calzolari, S. Curtarolo, and M. Buongiorno Nardelli, Physical Review B 88, 165127 (2013).
[2] Belopolski et al. in Sci. Adv. 3, 1501692 (2017). l