Charge and spin correlations in the superconducting state of the two-dimensional Hubbard model with cellular dynamical mean-field theory

The nature of the superconducting correlations in a doped Mott insulator remains a central question to understand the phenomenology of cuprate high-temperature superconductors. Here we use the two-dimensional Hubbard model with cellular dynamical mean-field theory on a 2x2 plaquette to address the interplay between d-wave superconductivity and Mott physics. We gain insights on the superconducting correlations by studying the probability obtained from the largest diagonal elements of the reduced density matrix of the 2x2 plaquette. We examine the probabilities of the plaquette eigenstates in the superconducting state and in the underlying normal state at finite temperature, and in a wide range of interaction strengths and doping levels. We show that upon condensation, the probability of half-filled singlets increases and of half-filled triplets decreases for all doping levels and all correlation strengths that we have investigated. We show that the reduction of spin fluctuations is reflected by a marked drop of the spin susceptibility upon entering the superconducting state.