Anomalous Hall effect of facing-target sputtered ferrimagnetic Mn₄N epitaxial films with perpendicular magnetic anisotropy

Epitaxial Mn4N films with different thicknesses were fabricated by facing-target reactive sputtering and their anomalous Hall effect (AHE) is investigated systematically. The Hall resistivity shows a reversed magnetic hysteresis loop with the magnetic field. The magnitude of the anomalous Hall resistivity sharply decreases with decreasing temperature from 300 K to 150 K. The AHE scaling law in Mn4N films is influenced by the temperature-dependent magnetization, carrier concentration and interfacial scattering. Different scaling laws are used to distinguish the various contributions of AHE mechanisms. The scaling exponent γ < 2 for the conventional scaling in Mn4N films could be attributed to the residual resistivity ρxx0. The longitudinal conductivity σxx falls into the dirty regime. The scaling of ρAH = αρxx0 + bρ n xx is used to separate out the temperature-independent ρxx0 from extrinsic contribution. Moreover, the relationship between ρAH and ρxx is fitted by the proper scaling to clarify the contributions from extrinsic and intrinsic mechanisms of AHE, which demonstrates that the dominant mechanism of AHE in the Mn4N films can be ascribed to the competition between skew scattering, side jump and the intrinsic mechanisms.