Gate-Dependent Nonlinear Hall Effect at Room Temperature in Topological Semimetal GeTe

We experimentally investigate nonlinear Hall effect as zero-frequency and second-harmonic transverse voltage responses to ac electric current for topological semimetal GeTe. A thick single-crystal GeTe flake is placed on the Si/SiO₂ substrate, where the p-doped Si layer serves as a gate electrode. We confirm that electron concentration is not gate-sensitive in thick GeTe flakes due to the gate field screening by bulk carriers. In contrast, by transverse voltage measurements, we demonstrate that the nonlinear Hall effect shows pronounced dependence on the gate electric field at room temperature. Since the nonlinear Hall effect is a direct consequence of a Berry curvature dipole in topological media, our observations indicate that Berry curvature can be controlled by the gate electric field. This experimental observation can be understood as a result of the known dependence of giant Rashba splitting on the external electric field in GeTe. For possible applications, the zero-frequency gate-controlled nonlinear Hall effect can be used for the efficient broad-band rectification.