  Nonequilibrium behavior and dynamic phase transition properties of a kinetic
Ising model under the influence of periodically oscillating random-fields have
been analyzed within the framework of effective field theory (EFT) based on a
decoupling approximation (DA). Dynamic equation of motion has been solved for a
simple cubic lattice ($q=6$) by utilizing a Glauber type stochastic process.
Amplitude of the sinusoidally oscillating magnetic field is randomly
distributed on the lattice sites according to bimodal and trimodal distribution
functions. For a bimodal type of amplitude distribution, it is found in the
high frequency regime that the dynamic phase diagrams of the system in
temperature versus field amplitude plane resemble the corresponding phase
diagrams of pure kinetic Ising model. Our numerical results indicate that for a
bimodal distribution, both in the low and high frequency regimes, the dynamic
phase diagrams always exhibit a coexistence region in which the stationary
state (ferro or para) of the system is completely dependent on the initial
conditions whereas for a trimodal distribution, coexistence region disappears
depending on the values of system parameters.
