Immediate ultrasmall current-tunable anomalous Hall effect

Electrical control of the anomalous Hall effect (AHE) provides an important gateway to reveal and regulate topological properties of spins. However, direct, immediate electrical tuning of the AHE in materials has been elusive, unfeasible, and rarely reported. Here, we demonstrate direct, immediate, nonlinear, electric current regulation of the AHE in a single, novel, van der Waals, room-temperature, ferromagnetic, ultrathin, two-dimensional (2D) crystal for intrinsic sensitivity of nodal electronic structures induced by 2D spin-orbit coupling (SOC) in a 2D quantum limit with an ultrasmall current (∼10² A cm⁻²). The multivalued electrical tuning of anomalous Hall resistance (R_AHE) ($\frac{{\mathit{R}}_{\mathit{A}\mathit{H}\mathit{E}}\mathbf{1}}{{\mathit{R}}_{\mathit{A}\mathit{H}\mathit{E}}\mathbf{2}}\ast \mathbf{100}\%$) is up to 584% and remains 126% at room temperature. The squared correlation between R_AHE and longitudinal resistance indicates an SOC-dominated Berry curvature-induced AHE. This immediate-current AHE with distinct dependence on the dimension, crystal layer, and electronic topology provides unique quantum platforms for probing the essence of the dimension and for low-power spintronics and brain-like quantum devices.