Detecting a possible chiral flux phase in the kagome metal CsV3Sb5

The unique geometry of the kagome lattice leads to magnetic frustration, topologically nontrivial electronic structures, and both electronic and magnon flat bands. The recent discovery of superconductivity in the two-dimensional kagome metal series AV3Sb5 (A = K, Rb, Cs) coexisting with charge order generated a flurry of research activities to understand the nature of charge order and superconductivity in these materials. The charge ordering in these materials is particularly unusual, and a novel chiral flux phase with circulating loop currents has been proposed. A key prediction for the chiral flux phase is that time reversal symmetry is broken. We propose to perform muon-spin relaxation measurements on CsV3Sb5 in both zero and longitudinal fields to test whether time reversal symmetry is broken below the charge ordering temperature, so as to unravel the nature of the charge ordering.