Moiré magnetic proximity in twisted WSe₂/WSe₂/CrI₃ trilayer: a first-principles study

Moiré superlattices in semiconducting transition metal dichalcogenides have garnered significant attention due to their ability to host localized, long-lived, and valley-polarized moiré excitons, which are promising candidates for single-photon emitters and play a crucial role in excitonic devices. These moiré excitons can also exhibit intriguing magnetic phenomena via the magnetic proximity effect when a magnetic monolayer is brought in close proximity to the moiré superlattice. Although this is an area of significant recent interest, it remains less explored from first-principles. In this work, we carry out a comprehensive first-principles study of moiré excitons and the moiré magnetic proximity effect in twisted WSe₂/WSe₂/CrI₃ trilayer using a recently developed non-collinear time-dependent density functional theory method with optimally tuned, screened, and range-separated hybrid exchange-correlation functionals. In addition to interesting excitonic properties, a giant Zeeman splitting for the moiré excitons at higher energies is observed, which is several times larger than that of the A exciton in WSe₂ bilayer. The moiré pattern generated by the twisted WSe₂ bilayer is imprinted onto the adjacent CrI₃ monolayer, resulting in a trapped exciton in the magnetic layer. This demonstrates the potential of tuning the properties of magnetic materials through moiré engineering.