Bicritical point and crossover in a two-temperature, diffusive kinetic Ising model

The phase diagram of a two-temperature kinetic Ising model which evolves by Kawasaki dynamics is studied using Monte Carlo simulations in dimension [ital d]=2 and solving mean-spherical approximation in general [ital d]. We show that the equal-temperature (equilibrium) Ising critical point is a bicritical point where two nonequilibrium critical lines meet a first-order line separating two distinct ordered phases. The shape of the nonequilibrium critical lines is described by a crossover exponent, [ital cphi], which we find to be equal to the susceptibility exponent, [gamma], of the Ising model.