Berry curvature origin of the thickness-dependent anomalous Hall effect in a ferromagnetic Weyl semimetal

Magnetic Weyl semimetals with spontaneously broken time-reversal symmetry exhibit a large intrinsic anomalous Hall effect originating from the Berry curvature. To employ this large Hall current for room temperature topo-spintronics applications, it is necessary to fabricate these materials as thin or ultrathin films. Here, we experimentally demonstrate that Weyl semimetal Co2MnGa thin films (20-50 nm) show a large anomalous Hall angle similar to 11.4% at low temperature and similar to 9.7% at room temperature, which can be ascribed to the non-trivial topology of the band structure with large intrinsic Berry curvature. However, the anomalous Hall angle decreases significantly with thicknesses below 20 nm, which band structure calculations confirm is due to the reduction of the majority spin contribution to the Berry curvature. Our results suggest that Co2MnGa is an excellent material to realize room temperature topo-spintronics applications; however, the significant thickness dependence of the Berry curvature has important implications for thin-film device design.

Automated summary

In this study, thin films of Weyl semimetal Co2MnGa are demonstrated to exhibit a large anomalous Hall angle at both low temperature and room temperature, making them promising for room temperature topo-spintronics applications. However, a significant decrease in the anomalous Hall angle is observed with decreasing thickness.