Abstract
New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Here we demonstrate that stoichiometric Bi1Te1, which is a natural superlattice of alternating two Bi2Te3 quintuple layers and one Bi bilayer, is a dual 3D topological insulator where a weak topological insulator phase and topological crystalline insulator phase appear simultaneously. By density functional theory, we find indices (0;001) and a non-zero mirror Chern number. We have synthesized Bi1Te1 by molecular beam epitaxy and found evidence for its topological crystalline and weak topological character by spin- and angle-resolved photoemission spectroscopy. The dual topology opens the possibility to gap the differently protected metallic surface states on different surfaces independently by breaking the respective symmetries, for example, by magnetic field on one surface and by strain on another surface.
Highlights
New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies
Spin–orbit coupling is included in this calculation and the colour represents the localization of the electronic states at the BL or at the quintuple layers (QLs)
Our study theoretically predicts by ab initio density functional theory (DFT) calculations that Bi1Te1 exhibits a dark surface perpendicular to the stacking direction which is free of time-reversal symmetry-protected surface states at the time-reversal invariant momenta (TRIM) points, due to weak topological Z2 indices (0;001)
Summary
New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Topological insulators (TIs) are bulk insulating materials that exhibit metallic conductivity on their boundaries via electronic edge (in two-dimensional (2D) TIs) or surface states (in three-dimensional (3D) TIs), which are guaranteed by the topology of the bulk band structure[1,2]. Electrons in these boundary states are spin polarized. Since it exhibits two topological properties, it was termed a dual TI8 Such a combination opens the possibility that controlled symmetry breaking would destroy certain surface states while keeping others intact. We investigate the electronic structure of Bi1Te1 by means of spin- and anglea b
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