Reentrance during nonequilibrium relaxation

Abstract

We consider nonequilibrium critical dynamics of the two-dimensional Ising model for which the initial state is prepared by switching on random fields with zero mean and variance $H$. In the initial state there is no magnetic order but the clusters of parallel spins have a percolation transition for small enough $H$. Using heath-bath dynamics we measure the relaxation of the magnetization which shows a reentrance in time. Due to cluster dissolution in the early time regime there is a decrease of the magnetization, followed by an increase due to nonequilibrium domain growth which itself turns to a decrease due to equilibrium relaxation. The power law decay of the nonequilibrium autocorrelation function is not influenced by the percolation in the initial state.