Ff. Assaad et al., CHARGE AND SPIN STRUCTURES OF A D(X(2)-Y(2)) SUPERCONDUCTOR IN THE PROXIMITY OF AN ANTIFERROMAGNETIC MOTT INSULATOR, Physical review. B, Condensed matter, 56(23), 1997, pp. 15001-15014
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.