REENTRANT FERROMAGNETISM IN A 2-DIMENSIONAL SPIN-3 2 ISING-MODEL WITHRANDOM NEAREST-NEIGHBOR INTERACTIONS/

The existence of a re-entrant ferromagnetic phase seems to be a genera l characteristic of systems with frustration and disorder even when no spin-glass phase exists. Using an effective field theory based on the use of a probability distribution that correctly accounts for the sin gle site kinematic relations, a two-dimensional nearest-neighbour rand om interaction spin-3/2 Ising model is studied in which the interactio ns are independent random variables distributed according to the follo wing law: P(J(ij) = p delta(J(ij) - J) + (1 - p) delta(J(ij) - alphaJ) , where J > 0. In a certain range of negative values of alpha, re-entr ant phase diagrams are found and the threshold p at which the critica l temperature goes to zero depends on alpha.