Extraordinary Hall effect in Co-Pd bilayers

This work is devoted to the study of the extraordinary Hall effect (EHE) in ferromagnet/normal-metal bilayers with a particular focus on surface and interface scattering. Systems selected are Co monolayers and series of Co-Pd bilayers, differing in the order of the materials deposition and the total and relative thicknesses. The extraordinary Hall coefficient was calculated using two models which we named “black box” and “two channels,” and compared them with Co monolayers. The EHE coefficient of bilayers with uniform Co layers was found to be independent of Pd thickness. Furthermore, contribution of Co-Pd interfaces to the effect is significantly weaker than Co-vacuum interface. In bilayers, as in monolayers, we find a linear correlation between the surface scattering contributions to resistivity and the EHE, which indicates that the skew scattering mechanism is the dominant source of the effect in these films.