Layer‐ and Charge‐State Dependent Magnetic Proximity Modulation of Valley Excitons in MoS ₂ /CrBr ₃ Heterostructures

Abstract The manipulation of valley degrees of freedom in transition metal dichalcogenides (TMDCs) via the magnetic proximity effect (MPE) is key to advancing next‐generation quantum and optoelectronic technologies. However, a comprehensive understanding of how MPE depends on layer configuration and excitonic charge state remains elusive. Here, a systematic study is reported on MPE‐induced magneto‐optical responses in monolayer and bilayer MoS ₂ interfaced with few and bulk CrBr ₃ . Photoluminescence spectroscopy reveals a charge state dependent MPE, consistent with a spin‐aligned interfacial charge transfer mechanism. Notably, CrBr ₃ introduces significant Zeeman splitting in 1L‐MoS ₂ , with a large splitting of 1.49 meV at zero field, consistent with the theoretical calculation of 1.8 meV. Under high magnetic fields, the g ‐factors of neutral excitons and trions are enhanced by factors of ≈2.3 and ≈1.8, respectively. In contrast, bilayer MoS ₂ exhibits a weaker response, highlighting the diminished interfacial exchange coupling in multilayer systems. The findings demonstrate a robust MPE in CrBr ₃ ‐based heterostructures and provide critical insights into layer and charge state‐dependent proximity effects, paving the way for tailored valleytronic functionalities in 2D materials.