Control of the exciton valley dynamics in atomically thin semiconductors by tailoring the environment

The exciton valley dynamics in van der Waals heterostructures with transition metal dichalcogenides monolayers is driven by the long-range exchange interaction between electron and hole exciton. It couples states active opposite circular polarizations resulting longitudinal-transverse splitting of excitons propagating monolayer plane. Here we study theoretically effect dielectric environment on demonstrate how encapsulation hexagonal boron nitride modifies splitting. We calculate spin/valley polarization relaxation due to that variation results significant, up five-fold, enhancement lifetime.