GLOBAL MEAN-FIELD PHASE-DIAGRAM OF THE SPIN-1 ISING FERROMAGNET IN A RANDOM CRYSTAL-FIELD

We study the phase diagram of the mean-field spin-1 Ising ferromagnet in a uniform magnetic field H and a random crystal field Delta(i), wit h probability distribution P(Delta(i)) = p delta(Delta(i) - Delta) + ( 1 - p)delta(Delta(i)). We analyse the effects of randomness on the fir st-order surfaces of the Delta-T-H phase diagram for different values of the concentration p and show how these surfaces are affected by the dilution of the crystal field.