Intrinsic Localized Excitons in MoSe/CrSBr Heterostructure.

Despite extensive studies on magnetic proximity effects, the fundamental excitonic properties of the 2D semiconductor-magnet heterostructures remain elusive. Here, the presence of localized excitons in MoSe/CrSBr heterostructures is unveiled, represented by a new photoluminescence emission feature, X. Our findings reveal that X originates from excitons confined by intrinsic defects in the CrSBr layer. Additionally, the degrees of valley polarization of the X and trion peaks exhibit opposite polarities under a magnetic field and closely correlate with the magnetic order of CrSBr. This is attributed to spin-dependent charge transfer across the heterointerface, supported by density functional theory calculations which reveal a type-II band alignment. Furthermore, the strong in-plane anisotropy of CrSBr induces unique polarization-dependent responses in MoSe emissions. This study highlights the crucial role of defects in shaping excitonic properties and offers valuable insights into spectrally resolved proximity effects in semiconductor-magnet van der Waals heterostructures.