The influence of nonequilibrium bulk conditions on the properties of the interfaces exhibited by a kinetic Ising-like model system with nonequilibrium steady states is studied. The system is maintained out of equilibrium by perturbing the familiar spin-flip dynamics at temperature $T$ with completely random flips; one may interpret these as ideally simulating some (dynamic) impurities. We find evidence that, in the present case, the nonequilibrium mechanism adds to the basic thermal one resulting on a renormalization of microscopic parameters such as the probability of interfacial broken bonds. On this assumption, we develop theory for the nonequilibrium “surface tension,” which happens to show a nonmonotonous behavior with a maximum at some finite $T$. The phase diagram, as derived from this effective interfacial free energy, exhibits reentrant behavior. In addition, interface fluctuations differ qualitatively from the equilibrium case, e.g., the interface remains rough at zero $T$, in full agreement with Monte Carlo simulations. We discuss on some consequences of these facts for nucleation theory, and make some explicit predictions concerning the nonequilibrium droplet structure.

• Received 22 May 2004

DOI:https://doi.org/10.1103/PhysRevB.70.245409