Control of spin and valley polarizations opens up opportunities for spintronic and quantum information applications. Monolayer transition-metal dichalcogenides (TMDs) offer an appealing platform to harness such polarizations. TMDs host excitons in valley-shaped regions of their band structure, featuring well-defined carrier spins and obeying chiral optical selection rules. However, the technological potential of excitons in TMDs is impeded by rapid spin–valley relaxation.
I will present our theoretical/computational efforts to address and enhance spin–valley polarizations in TMDs through strong coupling to photons. Recognizing that chiral light is a manifestation of photonic spin, I will show such strong coupling to allow for efficient spin transduction through the formation of "chiral polaritons". I will furthermore show how a breaking of chiral symmetry in optical cavities allows valley–spin relaxation to be suppressed in embedded TMDs.
I will also discuss our efforts to unravel how spin–valley relaxation in TMDs is driven by lattice phonons. Towards this goal, my group has advanced nonadiabatic methodologies that allow delocalized phonon modes and topological effects to be incorporated within a mixed quantum–classical framework. Results for TMDs indicate this approach to enable the modeling of solid-state phonon-driven processes at realistic dimensionalities.