MEAN-FIELD SOLUTION OF A NONEQUILIBRIUM RANDOM-EXCHANGE ISING-MODEL SYSTEM

We report first-order mean-field results for nonequilibrium random-exchange lattice systems, namely, Ising-like models whose kinetics involve a simultaneous, random competition between ferromagnetic and antiferromagnetic interactions that generally induces nonequilibrium steady states. We consider the competition between symmetric bonds. +/- J0, symmetric bonds competing with broken ones, +/- J0 and J = 0, nonsymmetric bonds, \J1\ and -\J2\, and some of those systems under an external magnetic field h. The time evolution and steady-state properties, including phase diagrams, are obtained for several lattice coordination numbers, e.g., the case of simple-cubic lattices of dimension d less-than-or-equal-to 3. A comparison is made with existing exact results for d = 1, h = 0, and +/- J0.