Chiral-loop-current and geometry-driven anisotropic nonreciprocal transport in kagome superconductor CsV₃Sb₅

Nonreciprocal transport phenomena serve as direct probes of symmetry breaking in quantum materials. The layered kagome metal CsV_3Sb_5 undergoes a charge-density-wave (CDW) transition, below which a chiral-loop-current order emerges, breaking time-reversal and inversion symmetries. Here, we report the observation of pronounced nonreciprocal charge transport in exfoliated thin flakes of CsV_3Sb_5, and systematically examine its anisotropy to map the symmetry-breaking pattern. We develop a phenomenological model that captures the role of chiral loop currents and current inhomogeneity in generating the nonreciprocal response. The nonreciprocal signal is strongly suppressed in Ta-doped CsV_3Sb_5, where the CDW phase is absent, confirming its intimate connection to the chiral ordered state. Our results reveal the symmetry breaking in the kagome superconductor CsV_3Sb_5 via nonreciprocal transport and highlight the profound connection between chirality and nonreciprocal transport.