Berry curvature contribution towards 1<i>s</i> − 2<i>p</i>± interlayer exciton ultrafast transition within a <i>R</i>-WSe2/MoSe2 heterobilayer

Abstract

We calculate the spectrum of interlayer neutral excitons in transition-metal-dichalcogenide WSe2/MoSe2 heterobilayers in R-stacking configuration. Most saliently, we show that, similar to neutral excitons and trions in monolayer transition-metal dichalcogenides, the spectrum is sensitive to the Berry curvature and thus quantum-geometric effects underlying the electron and hole wave functions. Due to the spatial separation between the electron and hole constituting the exciton in different layers, the Berry-curvature-induced splitting between the 2p+ and the 2p− exciton states is smaller than for monolayer excitons. Furthermore, we investigate the dependence of the exciton spectra on the dielectric environment and the twist angle between the two layers. Finally, the long-lived moiré interlayer exciton ground state (1s) enhances the possibility of creating brightened 2p± states using a circularly polarized medium-infrared probe from the 1s ground state. As a result, we determine the polarizability of the 1s–2p± transition, with the help of a two-level dressed model for the optical Stark effect.