Interface and magnetic characterization of FeCoV/NiO/FeCoV trilayers

The interface and magnetic properties of sputter-deposited FeCoV/NiO(t NiO)/FeCoV trilayers were analyzed by X-ray reflectivity, bulk magnetization, and polarized neutron reflectivity measurements. The layer depth profile, interface roughness, interface oxidation, etc. are obtained from specular X-ray reflectivity. The dc magnetization shows a coupled reversal of both FeCoV layers for t NiO < 20 nm, whereas for t NiO ≥ 20 nm, a step appears in the MH loop, which widens until t NiO reaches 40 nm. We investigated the magnetization state of the FeCoV layers during the magnetization reversal process by polarized neutron reflectivity measurements at selected points of the hysteresis loop. We conclude that the exchange coupling between the FM layers is accomplished by a spin twist mediated by the AF.