Biquadratic exchange coupling in an unequal Fe/Cr/Fe(1 0 0) trilayer

Abstract

We have investigated the magnetic properties of a (1 0 0)-oriented unequal trilayer, Fe(45 angstroms)/Cr(30 angstroms)/Fe(15 angstroms), by means of Brillouin light scattering and magnetization measurements. The experimental results show that this sample highlights the effect of biquadratic coupling which aligns the magnetization of the Fe layers at 90 °C to each other. We extracted the bilinear and biquadratic coupling strengths by fitting the experimental results with a theory that treats the static and dynamic responses on an equal footing. Our results confirm that the model describes both the static and dynamic properties even when the magnetization of the layers is aligned at 90°. The coupling strengths, and their temperature dependence, are discussed and compared with other results reported in the literature.