PHASE-DIAGRAMS OF A QUENCHED DECORATED ISING-MODEL WITH COMPETING INTERACTIONS

We study a quenched bond-decorated Ising model, on a square lattice, in which the nodal spins interact antiferromagnetically (J < 0) with its nearest neighbors and ferromagnetically (K > 0) with a decorated spin on the bond between them, which is randomly distributed over the lattice. We discuss, within the effective-field approach with correlation, the phase diagrams in both T-p and T-alpha spaces, where p is the decorated bond concentration and alpha the competing parameter alpha = \J\/K. It is pointed out that the present results may possibly have some relevance to elucidate the experimentally observed magnetic phase diagram of the planar superconducting material La2-xBaxCuO4 in the insulating phase.