Valley-contrasting interband transitions and excitons in symmetrically biased dice model
arXiv:2304.13404 · doi:10.1103/PhysRevB.104.195155
Abstract
We study the exciton states in the symmetrically biased dice model, the electronic structures of which have an isolated flat band between two dispersive bands. At 1/3 or 2/3 filling, the model describes a two-dimensional semiconductor with the band edge at two degenerate valleys. Because of qualitative changes in the eigenvectors resulting from the bias term, the interband transition between the flat band and a dispersive band is valley contrasting under circularly polarized light. In terms of an effective-mass model and a realistic electron-hole interaction, we numerically calculate the spectrum and wave functions of the intravalley excitons, which are treated as Wannier-Mott excitons. We also discuss the fine structures of the exciton spectrum induced by the intravalley and intervalley exchange interactions. The symmetrically biased dice model thereby proves to be a new platform for valley-contrasting optoelectronics.
12 pages, 5 figures
References in corpus (12)
- The electronic properties of graphene
- Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
- Dielectric function, screening, and plasmons in 2D graphene
- Tightly bound excitons in monolayer WSe2
- Valley Dependent Optoelectronics from Inversion Symmetry Breaking
- Probing Excitonic Dark States in Single-layer Tungsten Disulfide
- Exciton band structure of monolayer MoS2
- Excitons in anisotropic 2D semiconducting crystals
- Anisotropic exciton Stark shift in black phosphorus
- Determinisitic Writing and Control of the Dark Exciton Spin using Short Single Optical Pulses
- Accessing the dark exciton spin in deterministic quantum-dot microlenses
- Tightly bound excitons in two-dimensional semiconductors with a flat valence band