The nonlinear Hall effect induced by electrochemical intercalation in MoS ₂ thin flake devices

Abstract The nonlinear Hall effect (NLHE) has attracted extensive attention due to its complex physical origins and rectification characteristics with time-reversal symmetry. However, the special symmetry requirements have restricted the research and application of NLHE. Here we have developed an in-situ on-device electrochemical intercalation method to fabricate cetyltrimethylammonium cation (CTA + ) intercalated MoS 2 device. Structural characterization demonstrates that owing to the intercalation of CTA + , the atomic structure within the layers remains unchanged, but the layer distance expands from 0.61 nm to 1.06 nm, distinguish with the previous research. Due to the substantial injection of electrons by the intercalation process, the transport behavior of MoS 2 transforms from semi-metallic to metallic. By breaking of inversion symmetry introduced by the intercalation of CTA + , NLHE is induced. In the measurement of temperature-dependent NLHE, not only the main mechanism of skew scattering is confirmed by the nonlinear susceptibility analysis, but also a significant NLHE with the second-harmonic nonlinear Hall coefficient can be still observed under room temperature of 300 K. Our work expands the candidates of room-temperature NLHE materials and provides a new perspective for investigating the NLHE and symmetry engineering in two-dimensional materials.