PHASE-TRANSITIONS IN A DRIVEN LATTICE-GAS AT 2 TEMPERATURES

By suitably combining the uniformly driven lattice gas and the two-temperature kinetic Ising model, we obtain a generalized model that allows us to probe a Variety of nonequilibrium phase transitions, including a type not previously observed. This new type of transition involves ''longitudinally ordered'' steady states, which are phase-segragated states with interface normals parallel to the drive. Using computer simulations on a two-dimensional lattice gas, we map out the structure of the phase diagram, and the nature of the transitions, in the three-dimensional space of the drive and the two temperatures. While recovering anticipated results in most cases, we find one surprise, namely, that the transition from disorder to longitudinal order is continuous. Unless it turns out to be very weakly first order, this result is inconsistent with the expectation of field-theoretic renormalization group calculations.