Abstract
The anomalous Hall effect (AHE) in the reactively sputtered epitaxial and polycrystalline gamma'-Fe4N films is investigated systematically. The Hall resistivity is positive over the entire temperature range. The magnetization, carrier density and grain boundary scattering have a major impact on the AHE scaling law. The scaling exponent gamma in the conventional scaling of rho(AH) proportional to rho(gamma)(xx) is larger than 2 in both the epitaxial and polycrystalline gamma'-Fe4N films. Although gamma > 2 has been found in heterogeneous systems due to the effects of the surface and interface scattering on AHE, gamma > 2 is not expected in homogenous epitaxial systems. We demonstrated that gamma > 2 results from residual resistivity (rho(xx0)) in gamma'-Fe4N films. Furthermore, the side-jump and intrinsic mechanisms are dominant in both epitaxial and polycrystalline samples according to the proper scaling relation.