Phase ordering in 3d disordered systems

We study numerically the phase-ordering kinetics of the site-diluted and bond-diluted Ising models after a quench from an infinite to a low temperature. We show that the speed of growth of the ordered domain's size is non-monotonous with respect to the amount of dilution D: starting from the pure case D  =  0 the system slows down when dilution is added, as it is usually expected when disorder is introduced, but only up to a certain value $D^{\ast }$ beyond which the speed of growth raises again. We interpret this counterintuitive fact in a renormalization-group inspired framework, along the same lines proposed for the corresponding two-dimensional systems, where a similar pattern was observed. (paper)