Structural-order dependence of anomalous Hall effect in Co2MnGa topological semimetal thin films

We report on the large anomalous Hall effect (AHE) and its structural-order dependence for epitaxial Co2MnGa topological semimetal films fabricated by a sputtering method. The structural orders of the films were systematically changed from B2 to L21 upon tuning the film growth temperature. It was found that the AHE was dramatically enhanced when the Co2MnGa films contained the L21-ordered phase. A large anomalous Hall angle of ∼12.6% at 10 K (∼11% at 300 K) was achieved at maximum. The dependence of anomalous Hall conductivity on longitudinal conductivity suggests that the intrinsic contribution plays a major role in the AHE. Thus, the enhanced AHE with the L21 order is attributed to the improvement of topological electronic structures in the L21-ordered Co2MnGa films. This scenario also allows us to explain the structural-order dependence of magnetoresistance.