Observation of optical topological Hall effect in skyrmion-hosting Mott insulator

Abstract Noncoplanar spin structures with scalar spin chirality such as magnetic skyrmions exhibit emergent magnetic field as attested by topological Hall effect (THE). Although the impact of emergent field on electronic system has been extensively explored as transport phenomena of itinerant magnets, it has rarely been addressed in insulating magnets. Here, we show the optical THE in skyrmion-hosting Mott insulator GaV 4 Se 8 as detected through the magneto-optical Kerr effect (MOKE). The MOKE is found to be enhanced around optical transition of 0.4 eV near the band edge by the formation of the skyrmion lattice (SkL), manifesting the resonantly enhanced optical THE despite perfect disappearance of THE in dc limit because of insulating nature. The photon energy dependence of THE is captured by the theoretical model incorporating momentum-space Berry curvature induced by SkL formation in real space. Our findings represent the large emergent-field-driven electronic response in the Mott insulating state with strong electron correlation, leading to the development of low energy-consumption skyrmion devices.