Perpendicular interlayer coupling in Ni80Fe20/NiO/Co trilayers -: art. no. 027201

An in-plane perpendicular magnetic coupling between Ni80Fe20 and Co has been found in NiFe/NiO/Co trilayers for a NiO thickness ranging from 4 to 25 nm by magneto-optical Kerr effect and x-ray magnetic circular dichroism measurements. In the easy magnetization direction of the Co layer, the Co coercive field H-C increases when the thickness of the NiO layer t(NiO) increases. Because of the coupling, H-C is always larger than for NiO/Co bilayers with the same thicknesses. The saturation field of the NiFe layer H-S decreases when t(NiO) increases, indicating a weakening of the coupling. Numerical simulations show that the presence of interface roughness combined with a small value of the NiO anisotropy can explain the observed 90degrees coupling.