Tailoring Exciton Anisotropy and Valley via Magnetic Layer Thickness in 2D Heterostructures

The magnetic proximity effect offers a promising route to tailor the excitonic properties of transition metal dichalcogenides (TMDCs) via adjacent magnetic materials. While previous studies mainly focus on single-thickness magnetic materials, the layer-dependent exciton regulation remains largely underexplored. Here, ferromagnetic Cr₂Ge₂Te₆ (CGT) is used as a platform to explore the exciton performance regulation of TMDCs. Employing low-temperature, high-magnetic-field photoluminescence spectroscopy reveals a pronounced thickness-dependent modulation of exciton behavior. Circularly polarized PL measurements reveal distinct magnetic responses at the MoSe₂ and WSe₂ interfaces, attributed to strong super-super exchange coupling at the WSe₂-CGT interface. Valley polarization of WSe₂ excitons is dependent on CGT thickness, and the valley polarization is enhanced by 3 times by a thin layer of CCT. Further study shows that the linear polarization response of WSe₂ decays rapidly with the increase of CGT, indicating that CGT modulates linear polarization by regulating the exciton valley coherence time. These findings establish magnetic layer thickness as a crucial parameter for controlling exciton dynamics in TMDCs, offering new design strategies for magneto-optical and valleytronic devices based on van der Waals heterostructures.