Magnetic and moiré proximity effects in WSe2/WSe2/CrI3 trilayers

Integrating magnetic order to moiré superlattices is of significant scientific and technological interest. Based on first-principles calculations, we study the interplay of magnetic proximity and moiré proximity in WSe 2 /WSe 2 /CrI 3 trilayers with different stackings and twist angles. Large valley splitting is observed due to redistribution of the exciton charge density across layers via a super-exchange-like mechanism, and its electric-field dependence bears similarity to electrically tunable and valley-selective Feshbach resonances. The valley splitting can be magnified in moiré superlattices owing to the superposition of Umklapp excitons folded from moiré minibands, yielding spatially modulated and enhanced magnetic proximity. The moiré proximity effect is demonstrated via an imprinted moiré potential on CrI 3 layer and its feedback to the direct moiré potential on WSe 2 bilayers is observed. The cooperation between the direct and imprinted moiré potentials is shown to yield novel topological and correlated states.