Inhomogeneous order-parameter suppression in disordered d-wave superconductors

We report on a numerical study of disorder effects in 2D d-wave BCS superconductors. We compare exact numerical solutions of the Bogoliubov-deGennes (BdG) equations for the density of states $\rho(E)$ with the standard T-matrix approximation. Local suppression of the order parameter near impurity sites, which occurs in self-consistent solutions of the BdG equations, leads to apparent power law behavior $\rho(E) \sim |E|^\alpha$ with non-universal $\alpha$ over an energy scale comparable to the single impurity resonance energy $\Omega_0$. We show that the novel effects arise from static spatial correlations between the order parameter and the impurity distribution.