Flat dispersion at large momentum transfer at the onset of exciton polariton formation
Year: 2024
Type: article
Abstract: Excitons are quasiparticles, comprised of an electron excited from the valence band and attracted to the hole left behind, that govern transport properties in transition metal dichalcogenides. Excitonic coherence specifically needs to be understood to realise applications based on Bose-Einstein condensation and superfluidity. Here we used momentum-resolved electron energy-loss spectroscopy to obtain the complete energy-momentum dispersion of excitons in thin film and monolayer WSe2 across the entire Brillouin zone, including outside of the light cone and for a large energy-loss range (1.5–4 eV). The measured dispersion of the modes was found to be flat. This suggests that the excitations are at the onset of polaritonic mode formation, propagating in the confinement of nanometer thin and monolayer WSe2. In combination with helium ion microscopy nanopatterning it was possible to probe and control these excitonic modes in thin film WSe2 by modifying the local geometry through nanosized cuts.
Source: Communications Physics
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,790
Awards: Sequentielle Wechselwirkung niederenergetischer Elektronen mit nanostrukturierten Proben für quantensensitive Messungen, G434337789, Quantum Coherent Control: Self–Interference of Electron Beams with Nanostructures, G5200743168, Phasenrekonstruktion und
Spektroskopie von Atomen und Molekülen in und auf Graphen mittels fortgeschrittener
Elektronenmikroskopie, G5644380640, G6124737049, SFB 951: Hybrid Inorganic/Organic Systems (HIOS) for OptoElectronics, Variation und Kartierung von hybriden Polaritonen auf der Nanoskala, Kombination aus Rasterelektronen und Dunkelfeldmikroskop zur Untersuchung von ElektronenLichtWechselwirkungen
OpenAlex ID: W4404814222