On the spin – S random field Ising model

Abstract General Spin-S Ising model under the effect of the random field has been investigated within the effective field approximation. Effect of the bimodal distribution as a discrete, and Gaussian distribution as a continuous random field distribution, on the phase diagrams and order parameter of the system, have been determined. Detailed investigations display many interesting phenomena such as reentrant behavior and small ordered phase which can survive any degree of randomness. Underlying physical mechanisms have been given for the effect of the random field distributions. Especially role of the crystal field has been clarified.