Effects of intercomponent couplings on the appearance of time-reversal symmetry breaking fermion-quadrupling states in two-component London models

Detection of a bosonic metallic state that breaks the Z₂ time-reversal symmetry has been recently reported in Ba_1-xKₓFe₂As₂ with a doping level x≈0.8. This is a metallic state of fermionic quadruplets that breaks time-reversal symmetry. As such, it has no condensed Cooper pairs but has a long-range order between fermionic quartets. In the present paper, we investigate the emergence of this phase in a two-component London model via Monte Carlo simulations as a function of various intercomponent couplings.