Does the charge order in CsV3Sb5 break time-reversal symmetry
In plain words
Some experiments suggest that the charge order in CsV3Sb5 comes with tiny circulating electric currents (loop currents) that break time-reversal symmetry, while sensitive optical tests see nothing.
Precise statement
Determine whether the $2x2$ charge-density-wave state of CsV3Sb5 ($T_{\mathrm{CDW}} = 94\,\mathrm{K}$) breaks time-reversal symmetry, as in loop-current (chiral flux) phases. Reconcile muSR and field-trained transport and optical signals with high-resolution polar Kerr data and spin-polarized STM that found no signal. An answer is a symmetry-resolved measurement on the same crystals with sensitivity sufficient to detect the orbital moments predicted by loop-current theory.
What would settle it
Kerr, muSR and neutron or NMR measurements on the same crystals, with a calibrated sensitivity below the predicted loop-current moment.
Status in the literature
Unverified note
High-resolution polar Kerr studies (2022, 2025) found no signal, while muSR and some optical and transport data report time-reversal breaking.