Plasmonic nanocavity induced valley manipulation in monolayer transition metal dichalcogenides: A phenomenological description

Manipulating the valley degree of freedom in monolayer transition metal dichalcogenides (TMDs) is essential for advancing valleytronics-based information processing and transport. However, significant intervalley scattering causes valley signals to vanish at room temperature, posing a major challenge. To mitigate this, strategies involving magnetic fields, intense circularly polarized light, and in-plane electric fields have been explored to enhance valley polarization. Recently, increasing the excitons lifetimes using photonic nanostructures has emerged as a promising approach. In this work, we present a phenomenological model based on rate equations that describes and regulates the valley depolarization process in TMDs embedded within engineered photonic environments. Our findings demonstrate the potential to achieve near-unity valley polarization and enable negative valley polarization of dark excitons. Additionally, we identify extrinsically chiral nanocavities as effective platforms for generating chiral emission and spatially separating valley states. This research offers valuable insights for the nanophotonic design of devices with enhanced valley control, including manipulation of valley-polarized dark excitons, and paves the way for the development of advanced integrated valleytronic systems.