Potential influence of extrinsic skew scattering on the anomalous Hall effect in L 21-ordered Co2MnGa films

Magnetic Weyl semimetals such as Co2MnGa are famous for exhibiting large anomalous Hall effect (AHE) due to intrinsic Berry curvature in their unique electronic band structure. However, because the AHE is also known to originate from extrinsic mechanism such as skew scattering and side-jump, it is important to clarify the role of extrinsic contribution to the AHE. In this study, we investigate the thickness dependence of the extrinsic contribution to the AHE in L21-ordered Co2MnGa single-crystal films from 8 to 90 nm epitaxially grown on MgO(001) substrates. A conventional scaling equation successfully reproduces the AHE of the 90 nm-thick film. The extrinsic contribution ratio reaches around 50%. In contrast, for the lower thicknesses especially below 24 nm, the AHE results are deviated significantly from the conventional scaling. We find that the AHE results are reproduced well using a modified scaling equation including additional extrinsic skew scattering. Our results indicate significant influence of extrinsic contribution on the AHE of the Weyl semimetal Co2MnGa films.