Topologization of β-antimonene on Bi2Se3 via proximity effects

Abstract

Topological surface states usually emerge at the boundary between a topological and a conventional insulator. Their precise physical character and spatial localization depend on the complex interplay between the chemical, structural and electronic properties of the two insulators in contact. Using a lattice-matched heterointerface of single and double bilayers of β-antimonene and bismuth selenide, we perform a comprehensive experimental and theoretical study of the chiral surface states by means of microscopy and spectroscopic measurements complemented by first-principles calculations. We demonstrate that, although β-antimonene is a trivial insulator in its free-standing form, it inherits the unique symmetry-protected spin texture from the substrate via a proximity effect that induces outward migration of the topological state. This "topologization" of β-antimonene is found to be driven by the hybridization of the bands from either side of the interface.

Evolution of Topological Surface States Following Sb Layer Adsorption on Bi2Se3

“…The band structures for the natural stacking structures ( Figure 3 a,c) basically reproduce the ones in Reference [ 24 ], so the slightly different approach (self-consistent cell parameters for the BS substrate and unfixing the whole top QL) has no major impact on the bands. There are five main features which characterize the band structure: The topological surface states “TSSs” which form at the interface between the TI and the CI.…”

“…The BS surface is modeled with a slab derived from the optimized bulk cell. The difference from the one in Reference [ 24 ] is, first, that it uses lattice and internal parameters from the DFT calculation, while the latter has been built from experimental data, and, second, that the whole top QL is free to relax during surface relaxation. This has a minor effect on the thickness of the top QL Å, while the inter-layer distance between the top QL and the second top QL increases slightly to Å ( Å).…”

“…Thus, the first BL would occupy the H3 and the T4 site, and the second BL the T1 and the H3 site. These are the structures studied in the literature so far [ 19 , 20 , 23 , 24 ].…”

“…The color code gives information about the localization of the band (red: Sb atoms, blue: Bi/Se atoms). The plotting scheme is the same as in Reference [ 24 ].…”

“…The CI can, thus, be thought as being “topologized” under presence of the topological BS substrate. As a consequence, the TI/CI interface is not between BS substrate and the Sb layer, but at the surface of the Sb layer [ 24 ].…”