Broken Time Reversal Symmetry and Superconducting States in the Cuprates

Abstract

Recently, Kaminski et al. have reported that time reversal symmetry is broken in the pseudogap phase in the high temperature superconducting material Bi_2Sr_2CaCu_2O_{2+\delta} (Bi-2212). Here we examine the role of translationally invariant broken time reversal states on d_{x^2-y^2} superconductors. In particular, we determine the change in the superconducting order parameter structure. We find that the broken time reversal pseudogap state that is consistent with the experiment of Kaminski et al., gives rise to a novel mixed singlet-triplet pairing d+ip phase. This d+ip state is shown to give rise to a helical superconducting phase. Consequences of this d+ip state on Josephson experiments are discussed.