CHARGE AND SPIN STRUCTURES OF A D(X(2)-Y(2)) SUPERCONDUCTOR IN THE PROXIMITY OF AN ANTIFERROMAGNETIC MOTT INSULATOR

To the Hubbard model on a square lattice we add an interaction W that depends upon the square of a near-neighbor hopping. We use zero-temper ature quantum Monte Carlo simulations on lattice sizes up to 16 x 16, to show that at half-filling and constant value of the Hubbard repulsi on, the interaction W triggers a quantum transition between an antifer romagnetic Mott insulator and a d(x2-y2) superconductor. With a combin ation of finite-temperature quantum Monte Carlo simulations and the ma ximum entropy method, Eve study spin and charge degrees of freedom in the superconducting state. We give numerical evidence for the occurren ce of a finite-temperature Kosterlitz-Thouless transition to the d(x2- y2) superconducting state. Above and below the Kosterlitz-Thouless tra nsition temperature, T-KT, We compute the one-electron density of stat es N(omega), the spin relaxation rate 1/T-1, as well as the imaginary ad real part of the spin susceptibility chi((q) OVER RIGHT ARROW, omeg a). The spin dynamics are characterized by the vanishing of 1/T-1 and divergence of Re chi((q) OVER RIGHT ARROW = (pi, pi), omega = 0) in th e low-temperature limit. As T-KT is approached N(omega) develops a pse udogap feature and below T-KT Im chi((q) OVER RIGHT ARROW = (pi, pi), omega) shows a peak at finite frequency.