Effects of biaxial crystal-field on a ferrimagnetic bilayer system

By applying the differential operator technology, magnetic properties (phase transition, tricritical points and magnetization) of a ferrimagnetic bilayer system with biaxial crystal-field are studied within the framework of the effective-field theory with correlations. The effects of the biaxial crystal-field constants on the magnetic properties of the ferrimagnetic bilayer system consisting of two ferromagnetically coupled monolayers (A and B) with different spins (12 and 1, 32, 2) are discussed in detail for the case of simple cubic Ising-type structures. We find interesting phenomena in the system, such as two tricritical points exist on the curve in the system with a half integer spin (S=32), while there is only one tricritical point in the system with an integer spin (S=1,2) at certain values of the biaxial crystal-field. The ferrimagnetic system can exhibit compensation behavior, depending on the competition between the interlayer interaction and the biaxial crystal-field when the intralayer interactions J2 and J1 are fixed. The results obtained may be related to experimental work on rare-earth/transition-metal multilayer films.