Emergent chiral excitons correlated with spin textures in the van der Waals ferromagnet CrBr₃

Emergent magnetism in two-dimensional van der Waals crystals can stabilize optical quasiparticles through exchange coupling to real-space spin order. We show that CrBr₃ hosts an exciton whose presence and chirality depend on nonuniform spin textures. Polarization-resolved absorption with circular light at 1.5 K (well below T_C ≈ 37 K), reveals strong circular dichroism that is tunable by both the direction and magnitude of an external magnetic field. The exciton intensity grows at low out-of-plane fields, reaches a maximum at an intermediate field, and is quenched when the field drives uniform spin alignment. Magnetic force microscopy maps the evolution of the spin texture, and its field dependence closely mirrors the exciton response. These results establish a connection between real-space spin textures and chiral excitons and suggest a route to field-addressable chiral optical states in 2D magnets.