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In time-reversal invariant materials, Berry curvature dipole (BCD) gives rise to an anomalous nonlinear Hall effect (NLHE) when the inversion symmetry is broken. Although NLHE is observed in bilayer^[1] and few-layer^[2] WTe₂, BCD-induced NLHE in bulk single-crystals remains elusive. In this talk, we will report a bulk NLHE in a spin-valley locked Dirac semimetal BaMnSb₂^[3]. In this material, the distorted Sb zig-zag chains generate two gapped Dirac cones with spin-valley locking near the X point in the Brillouin zone, which creates a BCD. Our experiments show when an alternating current flows along the zig-zag chain direction across the crystal, a second-order Hall signal is present and exhibits the quadratic dependence on current. Through structure and domain tuning, we further demonstrate the observed NLHE is intrinsic. This finding shows NLHE measurements can serve as a probe for Berry curvature for non-centrosymmetric bulk crystals.

[1] Q. Ma, et al., Nature 565, 337 (2019).
[2] K. Kang, et al., Nat. Mater. 18, 324 (2019).
[3] J. Y. Liu, et al., ArXiv:1907.06318.