Current induced second-order nonlinear Hall effect in bulk WTe₂

The observation of second-order nonlinear Hall effect generally requires broken inversion symmetry and other spatial symmetries (such as out-of-plane C-2 symmetry) rather than time-reversal symmetry for the conventional Hall effect, which brings fascinating opportunities for the fundamental investigation and innovative concepts for device applications. However, the imposed symmetry constraints severely limit the accessibility of the second-order nonlinear Hall effect in many materials. Here, we report the observation of the second-order nonlinear Hall effect in bulk T-d-WTe2 with symmetry constraints under the application of direct current (DC). The observed second-order nonlinear Hall effect is strongly dependent on the external DC with its magnitude being vanished at zero driving DC and linearly increased with increasing driving DC. Furthermore, the driving DC induced second-order nonlinear Hall effect in bulk T-d-WTe2 exhibits the same twofold rotational symmetry as that of the intrinsic third-order nonlinear Hall effect, which is distinct from the second-order nonlinear Hall effect in few-layer T-d-WTe2. In addition, similar driving DC induced second-order nonlinear features are also observed in the longitudinal direction. These imply that the driving DC induced second-order nonlinear transport properties may share the same physical origins as that of the intrinsic third-order nonlinear transport. Scaling relationship analyses further demonstrate that extrinsic scattering-related mechanism plays a dominant role in the observed high-order nonlinear transport properties. Our work outlines a potential roadmap to control the second-order nonlinear Hall effect in materials where crystal symmetry forbids this effect with both fundamental research interest and technological device applications.