Chiral excitonics in monolayer semiconductors on patterned dielectric
arXiv:2110.07642 · doi:10.1103/PhysRevLett.128.217402
Abstract
Monolayer transition metal dichalcogenides feature tightly bound bright excitons at the degenerate valleys, where electron-hole Coulomb exchange interaction strongly couples the valley pseudospin to the momentum of exciton. Placed on periodically structured dielectric substrate, the spatial modulation of the Coulomb interaction leads to the formation of exciton Bloch states with real-space valley pseudospin texture displayed in a mesoscopic supercell. We find this spatial valley texture in the exciton Bloch function is pattern-locked to the propagation direction, enabling nano-optical excitation of directional exciton flow through the valley selection rule. The left-right directionality of the injected exciton current is controlled by the circular polarization of excitation, while the angular directionality is controlled by the excitation location, exhibiting a vortex pattern in a supercell. The phenomenon is reminiscent of the chiral light-matter interaction in nano-photonics structures, with the role of the guided electromagnetic wave now replaced by the valley-orbit coupled exciton Bloch wave in a uniform monolayer, which points to new excitonic devices with non-reciprocal functionalities.
6 pages, 4 figures
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Cited by in corpus (9)
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- Designing Band Structures by Patterned Dielectric Superlattices
- Cross-dimensional valley excitons from Förster coupling in arbitrarily twisted stacks of monolayer semiconductors
- Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
- Chiral excitonic systems in twisted bilayers from Förster coupling and unconventional excitonic Hall effects
- Artificial electrostatic crystals: a new platform for creating correlated quantum states
- Designing Flat Bands and Pseudo-Landau Levels in GaAs with Patterned Gates