Effects of an external drive on the fluctuation-dissipation relation of phase-ordering systems
arXiv:cond-mat/0205627 · doi:10.1209/epl/i2002-00281-7
Abstract
The relation between the autocorrelation $C(t,t_w)$ and the integrated linear response function $Ï(t,t_w)$ is studied in the context of the large-N model for phase-ordering systems subjected to a shear flow. In the high temperature phase $T>T_c$ a non-equilibrium stationary state is entered which is characterized by a non-trivial fluctuation-dissipation relation $Ï(t-t_w)=\tilde Ï(C(t-t_w))$. For quenches below $T_c$ the splitting of the order parameter field into two statistically independent components, responsible for the stationary $C^{st}(t-t_w)$ and aging $C^{ag}(t/t_w)$ part of the autocorrelation function, can be explicitly exhibited in close analogy with the undriven case. In the regime $t-t_w\ll t_w$ the same relation $Ï(t-t_w)=\tilde Ï(C^{st}(t-t_w))$ is found between the response and $C^{st}(t-t_w)$, as for $T>T_c$ . The aging part of $Ï(t,t_w)$ is negligible for $t_w\to \infty$, as without drive, resulting in a flat $Ï(C)$ in the aging regime $t-t_w\gg t_w$.
8 pages, 2 figures