Magnetic profile of Ni/Fe/Ni trilayers

The magnetic structure of Ni(1 1 1)/Fe/Ni trilayer was studied by Mossbauer spectroscopy. Two kinds of samples were studied differing each other in the substrate preparation, in the evaporation method of Fe-57 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 (similar to 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.