RANDOM DECORATED ANTIFERROMAGNETIC ISING-MODEL WITH MIXED SPINS

A new approach to studying random quenched decorated models is introdu ced, which after an approximation on the decoration transformation equ ation makes use of the exact solution of the partition function of the host lattice. The method is applied to study the phase diagram of an antiferromagnetic Ising square lattice randomly decorated with spins S 1 = +/-1;0 with probability p or S2 = +/- 1 with probability 1 - p, in the isotropic case, in which all the bonds are decorated. Several pha se diagrams are obtained spanning the various parameter spaces of the model.