Strong Room-Temperature Bulk Nonlinear Hall Effect in a Spin-Valley Locked Dirac Material

Nonlinear Hall effect (NLHE) represents a new type of Hall effect characterized by alternating current (a.c.) driven second-harmonic and rectified Hall voltage response under time-reversal symmetry and has wide application prospects such as THz detection. Practical device applications require room temperature (RT) NLHE with the ability to produce large photocurrent. However, among the current materials showing NLHE, the observed NLHE is primarily a low-temperature phenomenon. TaIrTe₄ is only the material showing NLHE at RT, but its NLHE only stems from surface layers. Bulk RT NLHE is highly desired due to its ability to generate large photocurrent but has not been reported yet. In this talk, we show the bulk spin-valley locked state in BaMnSb₂ can generate a strong bulk NLHE at RT. In the microscale devices, we observed not only a.c.-driven second-harmonic and rectification Hall responses but also a NLH response driven by d.c. Moreover, our measurements also find the NLHE of BaMnSb₂ shows a maximum near RT, which agrees well with the calculated energy dependence of the Berry curvature dipole, indicating the Dirac state origin of the observed NLHE. Additionally, we also demonstrated RT wireless microwave detection and frequency doubling based on the observed NLHE. These findings broaden the coupled spin and valley physics from 2D systems into a 3D system and lay a foundation for exploring bulk NLHE’s applications at RT.