Manipulation of anisotropic Zhang–Rice exciton in van der Waals antiferromagnets NiPS_3-xSe_x by anion substitution

The spin-entangled Zhang-Rice (ZR) exciton observed in the van der Waals magnet NiPS₃ has garnered significant interest due to its strong correlation with magnetic ordering and long coherence. Herein, we present a temperature- and polarization-dependent photoluminescence (PL) study of anion-substituted NiPS_3-xSe_x (x = 0.008, 0.03, 0.06, and 0.09) to explore the nature and dynamics of the ZR exciton. Our results reveal that even a small percentage of anion substitution effectively destroys and modulates the ZR exciton, as evidenced by the emergence of a weaker, lower-energy PL peak in addition to the primary ZR peak. Both peaks share the same anisotropic polarization but differ in their peak energy shift and intensity evolution with Se substitution, suggesting varying charge transfers of p-orbitals. Notably, the ZR exciton undergoes thermal destabilization at much lower temperatures than two-magnon excitations, highlighting that p-orbital inhomogeneity beyond the magnetic ordering structure is a decisive factor in driving its thermal quenching.