Scaling in late stage spinodal decomposition with quenched disorder.

We study the late stages of spinodal decomposition in a Ginzburg-Landau mean field model with quenched disorder. Random spatial dependence in the coupling constants is introduced to model the quenched disorder. The effect of the disorder on the scaling of the structure factor and on the domain growth is investigated in both the zero temperature limit and at finite temperature. In particular, we find that at zero temperature the domain size R(t) scales with the amplitude A of the quenched disorder as R(t)=${\mathit{A}}^{\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\beta}}}$f(t/${\mathit{A}}^{\mathrm{\ensuremath{-}}\ensuremath{\gamma}}$) with \ensuremath{\beta}\ensuremath{\simeq}1.0 and \ensuremath{\gamma}\ensuremath{\simeq}3.0 in two dimensions. We show that \ensuremath{\beta}/\ensuremath{\gamma}=\ensuremath{\alpha}, where \ensuremath{\alpha} is the Lifshitz-Slyosov exponent. At finite temperatue, this simple scaling is not observed and we suggest that the scaling also depends on temperature and A. Comparisons of the scaled structure factors for all values of A at both zero and finite temperature indicate only one universality class for domain growth. We discuss these results in the context of Monte Carlo and cell dynamical models for phase separation in systems with quenched disorder and propose that in a Monte Carlo simulation the concentration of impurities c is related to A by A\ensuremath{\sim}${\mathit{c}}^{1/\mathit{d}}$.