Time Reversal Breaking Superconducting State in the Phase Diagram of the Cuprates

Abstract

We review and extend a previous study on the symmetry of the superconducting state, stimulated by recent tunneling and Andreev reflection measurements giving robust evidences for the existence of a d x 2 −y 2 + idxy order parameter in the overdoped regime of two different cuprates. Looking for a possible second-order phase transition from a standard d x 2 −y 2 to a mixed and time reversal breaking state, we confirm the results of our previous analysis on La2−xSrxCuO4. In the case of Y1−yCayBa2Cu3O7−x as well, among all the allowed symmetries, the d x 2 −y 2 + idxy is the most favored one and the unconventional state is likely to occur in a small dome of the phase diagram located in the optimal-overdoped region and at very low temperatures.

The Ancient Romans’ Route to Charge Density Waves in Cuprates

“…When the charge density wave era discussed in Section 3 began, it was likewise clear that dynamical charge density wave described by Equation (4) could mediate Cooper pairing in the particle-particle channel [65], contribute to the properties of the pseudogap state [42][43][44], explain the possible occurrence of a time-reversal-symmetry-broken superconducting state [66,67], and be possibly related to a cutoff of the damped Cooper pair fluctuations contributing to the paraconductivity above T c [68], within the Aslamazov-Larkin theory.…”