Aging in ferromagnetic ordering: full decay and finite-size scaling of autocorrelation

Abstract

Nonequilibrium dynamics in Ising and Ginzburg-Landau models were studied for a nonconserved order parameter that mimics ordering in ferromagnets. The focus was on the understanding of the decay of the two time (t, tw; t > t(w)) order-parameter correlation function. For this quantity, a full form has been obtained empirically which, for t >> t(w), provides a power-law similar to (l/l(w)) (lambda), l and l(w) being the characteristic lengths at t and t(w), respectively. This empirical form was used for a finite-size scaling analysis to obtain the exponent lambda in space dimensions d = 2 and 3. Our estimates of lambda and understanding of the finite-size effects, for the models considered, provide useful information on the relevance of thermal noise. The values of lambda obtained are in good agreement with the predictions of a theory based on Gaussian auxiliary field ansatz.