Realizing a high magnetic moment in Gd/Cr/FeCo: The role of the rare earth

The search for materials or systems exhibiting a high magnetic saturation has been of longstanding importance. It has been suggested that increased saturation could be achieved by coupling a transition metal via a spacer to a rare earth. We report Gd/Cr/Fe70Co30 multilayer stacks and find reduced yet modulating magnetic moment as a function of Cr thickness. Through a micro structural analysis, the lowered moment is indicated by the nucleation of the ultrathin Gd films into a face-centered cubic (fcc) phase. We discuss the possible solution in terms of quasi-perfect lattice match seed material to promote growth of hcp Gd.