Spin-3/2 Ising model AFM/AFM two-layer lattice with crystal field

The spin-3/2 Ising model is investigated for the case ofantiferromagnetic (AFM/AFM) interactions on the two-layer Bethelattice by using the exact recursion relations in the pairwiseapproach for given coordination numbers q=3, 4 and 6 when thelayers are under the influences of equal external magnetic and equalcrystal fields. The ground state (GS) phase diagrams are obtained onthe different planes in detail and then the temperature-dependentphase diagrams of the system are calculated accordingly. It isobserved that the system presents both second- and first-order phasetransitions for all q, therefore, tricritical points. It is alsofound that the system exhibits double-critical end points andisolated points. The model also presents two Néel temperatures,T_N, and the existence of which leads to the reentrantbehaviour.