Berry curvature multipoles in Kagome superconductor CsV3Sb5.

Electronic nematic transitions in correlated systems often involve substantial reorganization of Berry curvature. Nonlinear transport measurements serve as a powerful tool for distinguishing between different types of Berry curvature multipoles that characterize nematic phases and topological changes. Herein, we systematically measured nonlinear responses up to the sixth harmonic in the Kagome superconductor CsV3Sb5. Our results identify the odd-order nonlinear Hall effect as the dominant signature of nematicity. During the superconducting transition, vortex dynamics induce rapid spatial variations in the phase gradient ∇ϕ, which significantly amplify the Berry curvature quadrupole (BCQ) relative to Berry curvature dipole (BCD). The third-order nonlinear response peaks sharply near the superconducting transition, where enhanced vortex-antivortex fluctuations and nonlinear vortex dynamics amplify the BCQ-related nonlinear Hall response. First-principles calculations further support this interpretation by revealing pronounced Berry-curvature quadrupoles induced by chiral loop-current order near the Fermi level. This work establishes BCQ as a sensitive probe of electronic nematicity, particularly when enhanced by superconducting vortex dynamics.