Hui Zhang, Daming Tian, Xiaobing Chen, Weijian Qi, Lu Chen, Min Li, Yetong Bai, Jine Zhang, Furong Han, Huaiwen Yang, Yuansha Chen, Yunzhong Chen, Jing Wu, Yongbing Xu, Fengxia Hu, Baogen Shen, Jirong Sun, Weisheng Zhao
ABSTRACT The nonlinear Hall effect (NLHE), an emergent phenomenon in noncentrosymmetric systems, enables the generation of a transverse voltage without an external magnetic field through a second‐order electrical response. However, achieving a sizable NLHE signal remains a critical challenge for its application in frequency‐doubling and rectifying devices. Here, we report a light‐induced giant enhancement of the NLHE in the 2D electron gas (2DEG) at the CaZrO 3 /KTaO 3 (111) interface. Under illumination, the second harmonic Hall voltage increases substantially and undergoes a sign reversal. Correspondingly, the second‐order transverse conductivity ( σ (2) yxx) increases by nearly five orders of magnitude, reaching 2.4 µm V −1 Ω −1 , while also reversing its sign. Scaling analysis identifies skew scattering as the dominant mechanism, which is highly tunable via optical gating. Photoexcitation pumps electrons from in‐gap states into the Ta 5 d conduction band, generating high‐mobility photocarriers that increase the cubic scattering time ( τ 3 ) and thereby, dramatically boost σ (2) yxx. First‐principles calculations further reveal that the Berry curvature triple changes sign as the Fermi level approaches the higher‐lying L z,+ subbands, in the Ta 5 d accounting for the observed sign reversal. Our work offers a new strategy to optically control the NLHE in oxide 2DEG systems, highlighting the tunability of nonlinear transport by optical excitation.