The exciton valley dynamics in van der Waals heterostructures with transition metal dichalcogenides monolayers is driven by the long-range exchange interaction between the electron and the hole in the exciton. It couples the states active in the opposite circular polarizations resulting in the longitudinal-transverse splitting of excitons propagating in the monolayer plane. Here we study theoretically the effect of the dielectric environment on the long-range exchange interaction and demonstrate how the encapsulation in the hexagonal boron nitride modifies the exciton longitudinal-transverse splitting. We calculate the exciton spin/valley polarization relaxation due to the long-range exchange interaction and demonstrate that the variation of the monolayer environment results in significant, up to five-fold, enhancement of the exciton valley polarization lifetime.
@article{arxiv.2010.01352,
title = {Control of the exciton valley dynamics in van der Waals heterostructures},
author = {A. I. Prazdnichnykh and M. M. Glazov and L. Ren and C. Robert and B. Urbaszek and X. Marie},
journal= {arXiv preprint arXiv:2010.01352},
year = {2021}
}