Enhanced Free-Electron-Photon Interactions at the Topological Transition in van der Waals Heterostructures.
basic_science · Level V
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- Record sourced from PubMed, PMID 39686910.
- Also identified by DOI 10.1021/acs.nanolett.4c05440.
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Abstract
Heterostructures composed of graphene and molybdenum trioxide (MoO<sub>3</sub>) can support in-plane hybrid polaritons in the infrared. The isofrequency contour for these subwavelength polaritons can exhibit a quasi-flat region when the topological transition occurs as the doping level of graphene is tuned. Such a topological transition can be useful for optical sensing and imaging at nanoscale. Here, by analyzing electron energy-loss spectroscopy (EELS), we theoretically demonstrate that free-electron-photon interactions in the heterostructure can be enhanced due to this quasi-flat region. Moreover, the free-electron-photon interaction is sensitive to the electron trajectory and is robust against certain types of defects in the structure. Furthermore, we show that the free-electron-photon interaction can undergo an ultrafast subpicosecond modulation by optical pumping and heating of graphene. Our findings may pave the way toward dynamical electron beam shaping, free-electron-based quantum light sources, and quantum sensing.