Surface coupling in Bi<sub>2</sub>Se<sub>3</sub> ultrathin films by screened Coulomb interaction.
basic_science · Level V
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- Record sourced from PubMed, PMID 37479683.
- Also identified by DOI 10.1038/s41467-023-40035-0 and PMC identifier 10362050.
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Abstract
Single-particle band theory has been very successful in describing the band structure of topological insulators. However, with decreasing thickness of topological insulator thin films, single-particle band theory is insufficient to explain their band structures and transport properties due to the existence of top and bottom surface-state coupling. Here, we reconstruct this coupling with an equivalently screened Coulomb interaction in Bi<sub>2</sub>Se<sub>3</sub> ultrathin films. The thickness-dependent position of the Dirac point and the magnitude of the mass gap are discussed in terms of the Hartree approximation and the self-consistent gap equation. We find that for thicknesses below 6 quintuple layers, the magnitude of the mass gap is in good agreement with the experimental results. Our work provides a more accurate means of describing and predicting the behaviour of quasi-particles in ultrathin topological insulator films and stacked topological systems.