odd-parity nematic phase above the charge density wave transition in a kagome metal

In this study, we present experimental evidence for the manifestation of an odd-parity electronic nematic state in CsV3Sb5, which appears at a temperature above the charge-density wave. Through our precise torque measurements, an in-plane magnetic anisotropy with twofold symmetry was observed, leading to a broken crystal rotational symmetry. Furthermore, within the temperature region between the charge-density wave and the nematic state, the manipulation of an external magnetic field in a conical trajectory elicits a distinct first-order phase transition, inferring broken time-reversal symmetry. These results provide thermodynamic evidence for an odd-parity nematic order in this system. Concurrently, elastoresistance experiments did not detect any significant anomalies proximate to the nematic phase, corroborating the hypothesized odd-parity order. These discoveries advocate for the presence of a previously unidentified loop-current state above the charge-density wave transition in CsV3Sb5.