Depth-resolved magnetic characterization of Fe films on NiO(001)

We used nuclear hyperfine spectroscopies and a 57Fe probe layer approach to study the depth-dependentmagnetic properties of ultrathin Fe films on NiO(0 0 1), a system exhibiting exchange bias. Conversionelectron Msbauer spectroscopy and nuclear resonance scattering of synchrotron radiation wereemployed. The samples were two Fe films with a thickness (8–10 ML) slightly above the critical thicknessfor the onset of ferromagnetism at room temperature, in which a 2 ML-thick probe layer, enriched in the57Fe Msbauer isotope, was embedded at different depths from the Fe/NiO interface. Both techniquesindicate that inside the film Fe has a metallic character, while at the interface with NiO different Fephases are present. The main conclusion is that already a few monolayers from the interface with NiOthe magnetic properties of Fe are bulk-like.