Mechanisms of interlayer exciton emission and giant valley polarizationin van der Waals heterostructures br

We perform a theoretical investigation about the valley dynamics of interlayer excitons (IXs) in MoS2/WS2heterostructure with AB stacking configuration grown on ferromagnetic substrate. We find that the interlayercharge transfer process changes dramatically the IX emission as well as its valley polarization (VP). Themagnetic proximity effect (MPE) exerted by ferromagnetic substrate, on the other hand, generates a zero-fieldvalley Zeeman splitting, which suppresses the depolarization induced by electron-hole exchange interaction.Remarkably, unlike usual exciton-phonon scattering, which is harmful to the VP, the phonon-assisted intervalleyscatterings between two split IX states in the different valleys foster an IX population imbalance in these states,giving rise to a giant VP. A combination of these experimentally tunable physical quantities (interlayer chargetransfer rate, MPE intensity and exciton-phonon coupling strength) provides a promising tool for intriguingemerging magneto-optical emissions and their VPs. Considering a large family of layered materials, this studysheds light on the path for development of van der Waals heterostructures with detectable IX emissions and giant VP.