The Crystal Field Effects On Spin-1 Ising Model With Afm/Afm Interactions On A Two-Layer Bethe Lattice

The crystal field effects and the influences of changing the coordination numbers on the phase diagrams of spin-1 Ising model are investigated for the case of antiferromagnetic (AFM)/AFM interactions on the two-layer Bethe lattice by using the pairwise approach when the layers are linked with the external magnetic fields. The ground state (GS) phase diagrams are calculated on different planes and are used as a guide together with the free energy and order-parameters in obtaining the temperature dependent phase diagrams. It was found that the system gives only one Neel temperature, TN, for q=3, but two TNs and reentrant behavior are observed for q=4 and 6. The first-order phase transitions and tricritical points are also observed for all q with appropriate values of the system parameters. The existence of the crystal field has increased the number of the GS configurations and also let the system to present first-order phase transitions for q=3 in comparison with no crystal field.