Two-temperature Ashkin-Teller model

Phase diagram of the two-temperature Ashkin-Teller model with Kawasaki dynamics has been investigated. The system is placed in contact with two heat baths at different temperatures, each of which controls the dynamics of nearest-neighbor exchange in the two perpendicular directions. It was observed that the second order phase transition lines (which separate the paramagnetic, ferromagnetic, and dimer phases) in the equilibrium model (equal temperatures) bifurcate into transition surfaces at nonequilibrium. The equilibrium four-state Potts point where all three orders meet extends into a line in the nonequilibrium case, along which these phases again meet.