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

摘要

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-temperature quantum Monte Carlo simulations on lattice sizes up to 16 x 16, to show that at half-filling and constant value of the Hubbard repulsion, the interaction W triggers a quantum transition between an antiferromagnetic Mott insulator and a d(x2-y2) superconductor. With a combination of finite-temperature quantum Monte Carlo simulations and the maximum entropy method, Eve study spin and charge degrees of freedom in the superconducting state. We give numerical evidence for the occurrence of a finite-temperature Kosterlitz-Thouless transition to the d(x2-y2) superconducting state. Above and below the Kosterlitz-Thouless transition temperature, T-KT, We compute the one-electron density of states 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, omega). 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 the low-temperature limit. As T-KT is approached N(omega) develops a pseudogap feature and below T-KT Im chi((q) OVER RIGHT ARROW = (pi, pi), omega) shows a peak at finite frequency. [References: 45]