  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 very large anomalous Hall angle
~11.4% at low temperature and ~9.7% at room temperature, which can be ascribed
to the nontrivial 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
