Growth law and superuniversality in the coarsening of disordered ferromagnets

Abstract

We present comprehensive numerical results for domain growth in the\ntwo-dimensional {\\it Random Bond Ising Model} (RBIM) with nonconserved Glauber\nkinetics. We characterize the evolution via the {\\it domain growth law}, and\ntwo-time quantities like the {\\it autocorrelation function} and {\\it\nautoresponse function}. Our results clearly establish that the growth law shows\na crossover from a pre-asymptotic regime with "power-law growth with a\ndisorder-dependent exponent" to an asymptotic regime with "logarithmic growth".\nWe compare this behavior with previous results on one-dimensional disordered\nsystems and we propose a unifying picture in a renormalization group framework.\nWe also study the corresponding crossover in the scaling functions for the\ntwo-time quantities. Super-universality is found not to hold. Clear evidence\nsupporting the dimensionality dependence of the scaling exponent of the\nautoresponse function is obtained.\n