Phase diagram of a driven interacting three-state lattice gas

We present Monte Carlo simulations of a three-state lattice gas, half-filled with two types of particles which attract one another, irrespective of their identities. A bias drives the two particle species in opposite directions, establishing and maintaining a non-equilibrium steady state. We map out the phase diagram at fixed bias, as a function of temperature and fraction of the second species. As the temperature is lowered, a continuous transition occurs, from a disordered homogeneous into two distinct strip-like ordered phases. Which of the latter is selected depends on the admixture of the second species. A first order line separates the two ordered states at lower temperatures, emerging from the continuous line at a non-equilibrium bicritical point. For intermediate fraction of the second species, all three phases can be observed.