Valley Selectivity Manipulation via Interfacial Magnon-Exciton Interactions in TMD/CrSBr Antiferromagnetic van der Waals Heterostructures

Valley properties of monolayer (ML) transition metal dichalcogenide (TMDs) can be effectively manipulated via magnetic proximity effects in van der Waals (vdW) heterostructures (HS) stacked with 2D ferromagnetic materials and ML TMDs. Antiferromagnetic materials with high-frequency and long-lived coherent magnons, allowing interactions between distinct excitations at the heterointerface, potentially serve as an alternative to valley manipulation via heterostructure constructions, however this remains elusive. Here, we demonstrated the existence of interfacial magnon-exciton interaction (IMEI) in the vdW heterostructure composed of ML MoSe ₂ and A-type antiferromagnetic CrSBr with in-plane magnetization. We proposed two mechanisms of IMEI, i.e., magnon-exciton scattering (MES), which induces the blueshift of excitonic states of MoSe ₂ below the Néel temperature of CrSBr, and magnon-assisting dark exciton recombination (MADER), which leads to the formation of magnon-exciton complexes. We found that MES induces a remarkable valley polarization (VP) enhancement of excitonic states from a completely quenched level, and the magnon-exciton complexes exhibit an increase in valley-contrasting circular dichroism when the spin orientation of CrSBr switched from in-plane to out-of-plane. Our work provides a new platform for manipulating excitonic and valley properties in non-magnetic semiconductors without external fields, opening up fresh opportunities of hybridized quasiparticles in quantum interconnects and opto-spintronics.