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 $d=2\mathrm{}$ and solving a mean-spherical approximation in general $d$. 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, $\varphi$, which we find to be equal to the susceptibility exponent, $\gamma$, of the Ising model.