Superconductivity, Pair Density Wave, and Néel Order in Cuprates*

Abstract

We investigate in underdoped cuprates possible coexistence of the superconducting order at zero momentum and pair density wave (PDW) at momentum Q = (π, π) in the presence of a Neel order. By symmetry, the d-wave uniform singlet pairing dS0 can coexist with the d-wave triplet PDW dTQ, and the p-wave singlet PDW pSQ can coexist with the p-wave uniform triplet pT0. At half filling, we find the novel pSQ + pT0 state is energetically more favorable than the dS0 + dTQ state. At finite doping, however, the dS0 + dTQ state is more favorable. In both types of states, the variational triplet parameters, dTQ and pT0, are of secondary significance. Our results point to a fully symmetric Z2 quantum spin liquid with spinon Fermi surface in proximity to the Neel order at zero doping, and to intertwined d-wave triplet PDW fluctuations and spin moment fluctuations along with the dominant d-wave singlet superconductivity at finite doping. The results are obtained by variational quantum Monte Carlo simulations.

Coexistence of antiferromagnetism and unconventional superconductivity in a quasi-one-dimensional flat-band system: Creutz lattice

“…[46] The staggered spin-triplet pairing is induced in the coexistence state of AFM and singlet SC and its free energy based on Ginzburg-Landau analysis has been shown in previous works, and some similar discussions have been done from the point of view of the symmetry of systems. [8,10,47] The staggered spin-triplet superconducting order parameter shows a small dome shape. It increases with hole-doping near half-filled with small δ and reaches a maximum value.…”