Interlayer exchange coupling in perpendicularly magnetized synthetic ferrimagnet structure using CoCrPt and CoFeB

Interlayer exchange coupling in synthetic ferrimagnet structures consisting of perpendicularly magnetized CoCrPt and in-plane magnetized CoFeB layers, which are coupled by a Ru thin spacer, were investigated. The magnetization of the CoFeB layer turned perpendicular to the film plane after annealing at 300°C because of the appearance of interlayer coupling from the CoCrPt layer. The coupling varied between antiferromagnetic and ferromagnetic depending on the Ru spacer thickness. The sign and strength of the coupling were also observed through analyses of magnetization curves and ferromagnetic resonance spectra.