A simple method of complex ferrimagnetic properties description of AB(1)AB(2)-superlattice structures with a strong perpendicular anisotropy contribution (Blume-Capel model)

We have studied the ferrimagnetic spin-1 AB(1)AB(2) superlattice in the pre sence of perpendicular single-ion anisotropy (Blume-Capel model) to have a direct evidence of the existence of multicompensation and tricritical effec ts. We present the theory based on the use of the exact solution for spin-1 Ising linear chain in external magnetic field. The free energy is calculat ed from the Bogolyubov's variational principle in frame of the transfer mat rix method. Then, we obtain the description of the second as well as first- order phase transition, together with the layered and total magnetization c urves. Our results (phase diagrams) indicate the possible existence of 1-3- compensation point effects for particular values of magnetic structure para meters. Mainly, the contribution of the perpendicular single-ion anisotropy is verified. (C) 2001 Elsevier Science B.V. All rights reserved.