Band Structure Engineering in 3D Topological Insulators*

We will present our recent combined experimental and theoretical results on band structure engineering in 3D topological insulator (3D TI) bilayers and superlattices. These results show how new topologies emerge in complex structures, as compared to the routine Fermi level control by alloying, and provide a starting point in search for novel topological phases. In topological pn-junction we have demonstrated Fermi level control by the relative thicknesses of the layers [1], while in superlattices which combine Bi₂Te₃ quintuple layers and Bi bilayers we have predicted dual topological properties, and experimentally demonstrated the existence of non-trivial topological crystalline insulator (TCI) crossings away from the surface Brillouin zone center [2].
Encouraged by these results we propose future research directions, which include preparation of heterostructures based on ferromagnetic insulators, and search for 2D materials which exhibit non-trivial topologies.
[1] M. Eschbach et al., “Realization of a vertical topological p-n junction in epitaxial Sb₂Te₃/Bi₂Te₃ heterostructures”, Nature Comm. 6, 8816 (2015).
[2] M. Eschbach et al., “Bi₁Te₁ is a dual topological insulator", Nature Comm. 8, 14976 (2017).