Emergent Trion-Phonon Coupling in Atomically-Reconstructed MoSe$_2$-WSe$_2$ Heterobilayers

TL;DR

This study uncovers a new trion-phonon interaction in MoSe2-WSe2 heterobilayers, showing a hybrid interlayer shear mode resonantly coupled with hybrid trions, which could impact future gate-controlled device experiments.

Contribution

The paper reports the discovery of a resonant hybrid interlayer shear mode coupled specifically with hybrid trions in MoSe2-WSe2 heterobilayers, supported by first-principles calculations.

Findings

Identification of a hybrid interlayer shear mode with asymmetric lineshape

Resonance observed only with hybrid trions, not neutral excitons

Strong coupling between Q-valley states and the shear mode

Abstract

In low-temperature resonant Raman experiments on MoSe$_2$-WSe$_2$ heterobilayers, we identify a hybrid interlayer shear mode (HSM) with an energy, close to the interlayer shear mode (SM) of the heterobilayers, but with a much broader, asymmetric lineshape. The HSM shows a pronounced resonance with the intralayer hybrid trions (HX$^-$) of the MoSe$_2$ and WSe$_2$ layers, only. No resonance with the neutral intralayer excitons is found. First-principles calculations reveal a strong coupling of Q-valley states, which are delocalized over both layers and participate in the HX$^-$, with the SM. This emerging trion-phonon coupling may be relevant for experiments on gate-controlled heterobilayers.