Single-particle properties of topological Wannier excitons in bismuth chalcogenide nanosheets

Journal Article (2023)
Authors

Lucas Maisel Licerán (Universiteit Utrecht)

Francisco Flórez (Universiteit Utrecht)

Laurens D.A. Siebbeles (TU Delft - ChemE/Opto-electronic Materials)

Henk T.C. Stoof (Universiteit Utrecht)

Research Group
ChemE/Opto-electronic Materials
Copyright
© 2023 Lucas Maisel Licerán, Francisco García Flórez, L.D.A. Siebbeles, Henk T.C. Stoof
To reference this document use:
https://doi.org/10.1038/s41598-023-32740-z
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 Lucas Maisel Licerán, Francisco García Flórez, L.D.A. Siebbeles, Henk T.C. Stoof
Research Group
ChemE/Opto-electronic Materials
Issue number
1
Volume number
13
DOI:
https://doi.org/10.1038/s41598-023-32740-z
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Abstract

We analyze the topology, dispersion, and optical selection rules of bulk Wannier excitons in nanosheets of Bi2Se3, a topological insulator in the family of the bismuth chalcogenides. Our main finding is that excitons also inherit the topology of the electronic bands, quantified by the skyrmion winding numbers of the constituent electron and hole pseudospins as a function of the total exciton momentum. The excitonic bands are found to be strongly indirect due to the band inversion of the underlying single-particle model. At zero total momentum, we predict that the s-wave and d-wave states of two exciton families are selectively bright under left- or right-circularly polarized light. We furthermore show that every s-wave exciton state consists of a quartet with a degenerate and quadratically dispersing nonchiral doublet, and a chiral doublet with one linearly dispersing mode as in transition metal dichalcogenides. Finally, we discuss the potential existence of topological edge states of chiral excitons arising from the bulk-boundary correspondence.