THEORETICAL-STUDY OF THE RANDOM MIXED BOND SPIN 3 2 ISING-MODEL/

The phase diagrams of a random mixed bond spin 3/2 Ising model is stud ied using a new technique in effective field theory that employs a pro bability distribution within the framework of single-site cluster theo ry based on the use of exact Ising spin identities. A model is adopted in which the nearest neighbour exchange coupling are independent rand om variables distributed according to the law P(J((ij))=p delta(J(ij)- J)+(1-p)delta(J(ij)-alpha J). General formulae applicable to structure s with arbitrary coordination number N are given. In a certain range o f negative values of alpha, we found re-entrant phase diagrams and the threshold p at which the critical temperature goes to zero depends o n (alpha.