Magnetic profile of Ni/Fe/Ni trilayers

The magnetic structure of Ni(1 1 1)/Fe/Ni trilayer was studied by Moessbauer spectroscopy. Two kinds of samples were studied differing each other in the substrate preparation, in the evaporation method of 57Fe and in vacuum condition. Fabrication by thermal evaporation in HV on a Ni buffer layer grown on mica and by electron beam bombardment in UHV on cleaned Ni(1 1 1) single crystal was used. The Ni substrate morphology was characterised by STM. Similar magnetic structure was found for the two systems, consisting of two well-defined features of the hyperfine field occurring at high value (∼28 T) and low one (<8 T). The high-field component was assigned to Fe atoms close to Fe-Ni interface with high-spin ferromagnetic state, and the low-field component to Fe atoms inside the Fe layer with low-spin antiferromagnetic state