Mean-Field Solution of the Mixed Spin-2 and Spin-5/2 Ising Ferrimagnetic System with Different Single-Ion Anisotropies

摘要

The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z｜J｜) for the spin-2 and (DB/z｜J｜) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z｜J｜,DB/z｜J｜) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z｜J｜ and DB/z｜J｜. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.