Magnetic and interface properties of Fe(0.82)Ni(0.18)/Co(001) superlattices.

The thickness dependence of the Fe magnetic hyperfine field and the interfacial intermixing of Fe(0.82)Ni(0.18)/Co superlattices, with the same thickness for FeNi and Co layers, have been investigated. A local concentration model using the magnetic hyperfine field values from the [Fe(0.82)Ni(0.18)](1 - x)Co(x) alloys has been used to interpret the field distribution in the superlattices and the Co concentration profiles over the superlattices. A relationship between the Fe magnetic hyperfine field and the Fe magnetic moment has been determined for the unordered [Fe(0.82)Ni(0.18)](1 - x)Co(x) and Fe(1 - x)Co(x) alloys. The magnetic hyperfine fields have been explained using two Fermi contact terms: (i) the core electron term proportional to the Fe magnetic moment with a proportionality constant of - 13 T/μ(B) and (ii) a valence electron term linearly dependent on the Co concentration. The direction of the magnetic moments is found to be in the sample plane except for the 1/1 superlattice, where an angle of about 45° is found.