Reversal effects in stochastic kink dynamics

Abstract

We study collective regular and stochastic dynamics in a chain of harmonically coupled particles subjected to an on-site potential with two degenerate energy wells but with differing frequencies of small-amplitude oscillations at their minima. We identify and study asymmetry-induced properties of a Peierls-Nabarro relief, kink-antikink interactions, and stochastic kink motion. In particular, we predict analytically and confirm numerically directed noise-induced soliton motion when the chain particles are driven by white and exponentially correlated noise. The difference of frequencies of oscillations in the vicinity of the wells is shown to be a sufficient condition for the existence of such a directed kink motion. We find that under certain conditions a reversal of the soliton motion takes place; these conditions involve the noise properties such as a critical correlation time or noise strength or the presence of an external d.c. field. In particular, we find that above some critical value of temperature, the directed soliton transport occurs against an applied d.c. field.