We investigate the phase diagram of a mixed spin-$\frac{1}{2}$–spin-1 Ising system in the presence of quenched disordered anisotropy. We carry out a mean-field and a standard self-consistent Bethe-Peierls calculation. Depending on the amount of disorder, there appear additional transition lines and multicritical points. Also, we report some connections with a percolation problem and an exact result in one dimension.

• Received 24 November 2000

DOI:https://doi.org/10.1103/PhysRevB.63.184415