Response function of coarsening systems

The response function of domain growth processes, and in particular the violation of the fluctuation-dissipation theorem, are studied both analytically and numerically. In the asymptotic limit of large times, the fluctuation-dissipation ratio X, which quantifies this violation, tends to one if C > m <Superscript>2</Superscript> and to zero if C > m <Superscript>2</Superscript>, corresponding to the fast (“bulk”) and slow (“domain-wall”) responses, respectively. In this paper, we focus on the pre-asymptotic behavior of the domain-wall response. This response is shown to scale with the typical domain length L(t) as 1/L(t) for dimension d > 2, and as ln(L(t))/L(t) for d=2. Numerical results confirming this analysis are presented. Copyright Società Italiana di Fisica, Springer-Verlag 1999