Absence of Broken Time-Reversal Symmetry in the Pseudogap State of the High Temperature La2-xSrxCuO4 Superconductor from Muon-Spin-Relaxation Measurements

We have performed zero-field muon-spin-relaxation measurements on single crystals of La(2-x)SrxCuO4 to search for spontaneous currents in the pseudogap state. By comparing measurements on materials across the phase diagram, we put strict upper limits on any possible time-reversal symmetry breaking fields that could be associated with the pseudogap. Comparison between experimental limits and the proposed circulating current states effectively …