Anomalous Non-Superconducting Time-Reversal-Symmetry Breaking State in Multicomponent Superconductors

Multicomponent superconductors can break time-reversal symmetry, either due to phase frustration in Josephson-coupled superconductors with at least three components, or due to higher-order Josephson coupling in superconductors with at least two components. Beyond mean-field theory, such systems may have an anomalous phase in which time-reversal symmetry is broken despite superconducting order being absent. Models of the aforementioned type have been argued to describe the multiband superconductor Ba_1-xK_xFe₂As₂. We report properties of the fluctuation-induced precursory normal state that breaks time-reversal symmetry.