Giant Optical Anisotropy Induced by Magnetic Order in FePS3/WSe2 Heterostructures

Abstract Magnetic 2D materials offer a promising platform for manipulating quantum states at the nanoscale. Recent studies have underscored the significant influence of 2D magnetic materials on the optical behaviors of transition‐metal dichalcogenides (TMDs), revealing phenomena such as interlayer exciton‐magnon interactions, magnetization‐dependent valley polarization, and an enhanced Zeeman effect. However, the controlled manipulation of anisotropic optical properties in TMDs via magnetism remains challenging. Here, the magnetic ordering in FePS 3 profoundly impacts the optical characteristics of WSe 2 , achieving a giant linear polarization degree of 5.1 in exciton emission is demonstrated. This is supported by a detailed analysis of low‐temperature photoluminescence (PL) and Raman spectra from nL‐FePS 3 /WSe 2 heterostructures. These findings indicate that a phase transition in FePS 3 from paramagnetic to antiferromagnetic enhances interlayer Coulomb interactions, inducing a transition from non‐polar to polar behavior in the heterostructures. Additionally, valley‐polarized PL spectra under magnetic fields from −9 to 9 T reveal the influence of FePS 3 on valley polarization and Zeeman splitting of excitons in monolayer WSe 2 . These results present a novel strategy for tailoring the optoelectronic properties of 2D magnetic van der Waals heterostructures, paving the way for advancements in nanoscale device design.