Multicritical behavior of the antiferromagnetic Blume–Emery–Griffiths model

The multicritical behavior of the antiferromagnetic spin- Blume–Emery–Griffiths model in an external magnetic field is studied within the lowest approximation of the cluster variation method. We have investigated the thermal variations of order parameters for different values of interaction parameters and external magnetic field and constructed the resulting phase diagrams. The model exhibits distinct critical regions, including the first-order, second-order tricritical point, double critical point and zero critical point. Comparison of the phase diagrams with closely related systems is made.