Minimal current phase and universal boundary layers in driven diffusive systems

Hager, J. S.
Institut für Theoretische Physik, Technische Hochschule Aachen,
D-52056 Aachen, Germany

Krug, J.
Fachbereich Physik, Universität GH Essen,
D-45117 Essen, Germany

Popkov, V.
Fachbereich Physik, Freie Universität Berlin,
D-14195 Berlin, Germany
Institute for Low Temperature Physics,
310164 Kharkov, Ukraine

Schütz, G. M.
Institut für Festkörperforschung, Forschungszentrum Jülich,
D-52056 Aachen, Germany


We investigate boundary-driven phase transitions in open driven diffusive systems. The generic phase diagram for systems with short-ranged interactions is governed by a simple extremal principle for the macroscopic current which results from an interplay of density fluctuations with the motion of shocks. In systems with more than one extremum in the current-density relation one finds a minimal current phase even though the boundaries support a higher current. The boundary layers of the critical minimal current and maximal current phases are argued to be of a universal form. The predictions of the theory are confirmed by Monte-Carlo simulations of the two-parameter family of stochastic particle hopping models of Katz, Lebowitz and Spohn and by analytical results for a related cellular automaton with deterministic bulk dynamics. The effect of disorder in the particle jump rates on the boundary layer profile is also discussed.