Symmetry breaking in solids is one of the central issues of condensed matter physics. To date, many unique physical properties and novel functionalities have been explored in noncentrosymmetric crystals. Among them, nonlinear anomalous Hall effect, which is the directional dependent spontaneous Hall effect under time reversal symmetry, is an emerging nonlinear quantum transport [1]. So far, it has been investigated in low-symmetric materials such as WTe₂ and TaIrTe₄ with only one mirror plane and resultant Berry curvature dipole [2-4]. In principle, however, noncentrosymmetric crystals with higher symmetry (e.g., trigonal crystals) can also host nonlinear anomalous Hall effect [5] despite the lack of Berry curvature dipole. Moreover, the search for anomalous Hall effect in exotic quantum phases including superconductivity has been missing and important challenge.

In this work, we report nonlinear anomalous Hall effect in noncentrosymmetric trigonal superconductor PbTaSe₂. We observed nonlinear transport signals, which show the characteristic directional dependence reflecting the trigonal crystal symmetry in both normal and superconducting states.

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[2] Q. Ma et al., Nature 565, 337–342 (2019).

[3] K. Kang et al., Nat. Mater. 18, 324–328 (2019).

[4] D. Kumar et al., Nat. Nanotechnol. 16, 421-425 (2021).

[5] H. Isobe et al., Sci. Adv. 6, eaay2497 (2020).