Effects of composition on the stability of the magnetic order of ferrimagnetic multilayers

Abstract

We study the field induced instability of the antiferromagnetic phase of magnetic multilayers consisting of a stacking of uniaxial ferromagnetic films, (formula presented) and (formula presented) with thicknesses (formula presented) and (formula presented) coupled through a nonmagnetic (NM) spacer. The external field is along the uniaxial axis, in the plane of the films, and the composition is varied by choosing arbitrary values of the relative thickness (formula presented) We calculate the critical value of the external field (formula presented) and examine the nature of the phase transition. We find that (formula presented) does not change with the multilayer thickness in the case of multilayers with an even number of magnetic layers, (formula presented) n arbitrary). The nature of the phase transition and the critical field depend on the value of (formula presented) and the minimum value of (formula presented) corresponds to (formula presented) For a multilayer with an odd number of magnetic layers we find that the thickness dependence of the critical field is significantly affected by the value of (formula presented). © 2002 The American Physical Society.