Magnetic trilayers with bilinear and biquadratic exchange couplings: Criteria for the measurement of and

Abstract

We have analytically calculated phase boundaries of magnetic trilayers with bilinear and biquadradic exchange couplings in order to investigate possible phase transitions in these systems as the external magnetic field, applied either along an easy or a hard magnetization axis, is varied. A simple scheme is obtained for both antiferromagnetic and ferromagnetic couplings that is shown to be consistent with magnetization curves previously measured in different systems. In addition, experimental data regarding static and dynamic responses in sputtered (100) (Formula presented) Å) are reported for the Cr thickness in the range 15 Å< (Formula presented) Å. As a result, our model calculations indicate that the bilinear and biquadratic exchange coupling constants, (Formula presented) and (Formula presented), cannot be accurately determined from a fit to the experimental data when the ratio (Formula presented) and if only the main magnetization axes are considered. © 1998 The American Physical Society.