We propose an explanation for the experiment by Schemm et al., Phys. Rev. B 91, 140506 (2015) where the polar Kerr effect (PKE), indicating time-reversal symmetry (TRS) breaking, was observed in the hidden-order (HO) phase of URu2Si2. The PKE signal on warmup was seen only if a training magnetic field was present on cool-down. Using a Ginzburg-Landau model for a complex order parameter, we show that the system can have a metastable ferromagnetic state producing the PKE, even if the HO ground state respects TRS. We predict that a strong reversed magnetic field should reset the PKE to zero.
@article{arxiv.1704.06231,
title = {A Model for Metastable Magnetism in the Hidden-Order Phase of URu2Si2},
author = {Lance Boyer and Victor M. Yakovenko},
journal= {arXiv preprint arXiv:1704.06231},
year = {2017}
}