Perpendicular magnetic anisotropy in Pd/Co and Pt/Co thin-film layered structures

Abstract

rf sputtered Pd/Co and Pt/Co thin-film layered structures (LS) have perpendicular magnetic anisotropy, when the Co layer is ultrathin (<8 Å in Pd/Co and <14 Å in Pt/Co). The Co thickness (T) dependence of the anisotropy energy (Ku∼T) and the effective anisotropy field (HK∼1/T) in Pd/Co LS support an interfacial anisotropy as the source of the perpendicular magnetic easy axis. In contrast, the anisotropy is independent of Co thickness for thin Co layers in Pt/Co LS, and thus the mechanism for the perpendicular easy axis is thought to be different. We describe magnetization, resistivity, and x-ray diffraction data that consistently support sharper interfaces in Pd/Co LS than in Pt/Co LS.