Anomalous Hall effect in polycrystalline Ni films

We systematically studied the anomalous Hall effect in a series of polycrystalline Ni films with thickness ranging from 4 to 200 nm. It is found that both the longitudinal and anomalous Hall resistivity increased greatly as film thickness decreased. This enhancement should be related to the surface scattering. In the ultrathin films (4–6 nm thick), weak localization corrections to anomalous Hall conductivity were studied. The granular model, taking into account the dominated intergranular tunneling, has been employed to explain this phenomenon, which can explain the weak dependence of anomalous Hall resistivity on longitudinal resistivity as well.

► Weak localization corrections to AH conductivity in the ultrathin Ni films with a thickness of 4–6 nm.
► Observed weak dependence of anomalous Hall resistivity on longitudinal resistivity in the ultrathin films.
► The results could be understood by the granular model taking into account the dominated tunneling resistance.