The critical and compensation temperatures for the mixed spin-32 and spin-2 Ising model

The critical and the compensation temperatures of the mixed spin-32 and spin-2 Ising ferrimagnetic system is examined on the Bethe lattice by using the exact recursion equations. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/q|J|DA/q|J|, DB/q|J|DB/q|J|) plane. Then in order to investigate the influences of the sublattice crystal fields at higher temperatures, the phase diagrams on the (kT/|J|,DA/|J|kT/|J|,DA/|J|) and (kT/|J|,DB/|J|kT/|J|,DB/|J|) planes are-calculated for given values of DB/|J|DB/|J| for spin-2 and DA/|J|DA/|J| for spin-32, respectively. Besides the second-order phase transition lines, two types of the first-order lines one ending at a tricritical point and the other at an isolated critical point are found. The model also exhibits up to four compensation temperatures for appropriate values of the system parameters. The calculations are carried out for the coordination number q=3q=3 corresponding to the honeycomb lattice.