Anomalous Hall effect in nickel and nickel-rich nickel-copper alloys

Hall-effect measurements on nickel and its alloys containing 9.38, 18.77, 28.32, and 38.13 at.% of copper were performed from 77° K to their ferromagnetic Curie temperatures in fields up to 15 kOe. An appraisal of the theories proposed to understand the anomalous Hall effect (AHE) in ferromagnetic compounds in the light of the present experimental data showed that (i) one (or more) of the scattering processes (impurity, phonon, and spin-disorder scattering) dominantly contributes to the AHE in different temperature ranges which, in turn, are different for different samples, (ii) spin-disorder scattering surpasses the contribution to the AHE arising from all other scattering processes for temperatures in the vicinity of the ferromagnetic Curie temperature for all the specimens, and (iii) $d$-spin—$s$-orbit interaction plays a vital role so for as the AHE in pure nickel is concerned, whereas the intrinsic spin-orbit interaction is important for understanding the AHE behavior in nickel-copper alloys.