Absence of spontaneous magneto-optical Kerr effect in the charge density wave phase of the Kagome metal CsV₃Sb₅

The Kagome metals AV₃Sb₅ (A = K, Cs, Rb) provide a rich platform for intertwined orders, where evidence for a time-reversal symmetry breaking (TRSB) charge density wave (CDW) state, possibly due to the long-sought loop currents, has been reported in µSR, chiral transport, and magneto-optical Kerr effect (MOKE) experiments. Intriguingly, reported spontaneous MOKE signals differ by orders of magnitude even when using the same wavelength. Here we perform [1] comprehensive 1550 nm MOKE measurements on CsV₃Sb₅ under experimental conditions identical to those in prior reports. We observe no spontaneous MOKE with 0.1 µrad uncertainty, independent of the magnitude of training fields and temperature sweep rates. We suggest that sample variations rather than experimental conditions are the likely explanation for the discrepancy between 1550 nm studies, as the intertwined instabilities in CsV<!--[if gte msEquation 12]> style='mso-bidi-font-style:normal'>μrad₃Sb₅ are known to be sensitive to perturbations such as pressure and strain that can potentially induce inhomogeneous CDW ground states with different magnetic structures and symmetries.

[1] https://doi.org/10.48550/arXiv.2301.08853