Phonon-exciton Interactions in WSe2 under a quantizing magnetic field

Strong many-body interaction in two-dimensional transitional metal dichalcogenides provides a unique platform to study the interplay between different quasiparticles, such as phonon replica emission and modified valley-selection rules. A large out-of-plane magnetic field is expected to modify the exciton-phonon interactions by quantizing excitons into discrete Landau levels. In this talk, I will discuss our exploration of the phonon–exciton interaction in monolayer WSe2 in the regime of Landau quantization. For the well-resolved PL peaks from different phonon replicas of the dark trion, the phonon-exciton interaction can lift the inter-Landau-level transition selection rules, manifested by a distinctively different Landau fan pattern compared to that of bright trions. The significant valley-Zeeman shift increase of Landau quantization suggests strong many-body effects on the phonon-exciton interaction. Our work demonstrates monolayer WSe2 as an intriguing playground to study phonon-exciton interactions and their interplay with charge, spin, and valley.