Enhanced nonlinear Hall effect by Cooper pairs near the superconducting phase transition

Unlike the linear Hall effect, which requires broken time-reversal symmetry, the nonlinear Hall effect may occur in time-reversal-symmetric systems as long as a nonzero Berry curvature dipole exists in the absence of inversion symmetry. Interestingly, the presence of time-reversal symmetry is consistent with and thus allows a direct transition into a superconducting phase. Indeed, superconductivity has been established in various nonlinear Hall materials, such as WTe2 and MoTe2, at sufficiently low temperatures. We find that the nonlinear Hall response should be significantly enhanced near the superconducting criticality, dominated by the Aslamazov-Larkin contributions augmented by superconducting fluctuations, which we attribute to the Berry curvature dipole and a divergent lifetime 𝜏∼(𝑇−𝑇𝑐)−1 of the Cooper pairs, instead of the single electrons. Such a controlled enhancement brings the nonlinear Hall effect into various simple experimental observations and practical applicational potentials.