The magnetic properties of the mixed spin-12 and spin-1 Ising ferromagnetic system with a crystal–field interaction in the absence and presence of an external magnetic field are studied by using the cluster variation method. Thermal variations of order parameters are investigated and the...

We investigate the temperature dependence of the order parameters of the Blume–Capel model for zero magnetic field in the lowest approximation of the cluster variation method which is identical to the mean-field approximation. Besides the stable branches of the order parameters, we establish...