Electric-Field Switching of Anomalous Hall Effect and Spontaneous Nonlinear Transport in a Ferromagnetic Rashba Metal

The broken inversion symmetry at interfaces of complex oxides gives rise to emergent phenomena, such as ferromagnetism and Rashba spin-orbit coupling (SOC) which influence the electronic structure by entangling spin and momentum. While the interplay between Rashba SOC and ferromagnetism is theoretically intriguing, its experimental manifestations remain largely unexplored. Here we demonstrate a ferromagnetic Rashba two-dimensional electron gas at a SrTiO₃-based interface in which the anomalous Hall effect (AHE) and nonlinear transport can be tuned electrostatically. The AHE varies in amplitude but also reverses sign with gate voltage due to the reversal of the net Berry curvature, providing a distinct form of magnetoelectric switching. In addition, we observe spontaneous nonreciprocal transport at zero magnetic field whose polarity is governed by the remanent magnetization and is strongly gate-tunable. These results establish oxide-based ferromagnetic Rashba 2DEGs as a platform to engineer Berry-curvature landscapes and explore gate-tunable spintronic functionalities driven by band topology.