  Various Co2 based Heusler compounds are predicted to be Weyl materials. These
systems with broken symmetry possess a large Berry curvature, and introduce
exotic transport properties. The present study on epitaxially grown Co2TiSn
films is an initial approach to understand and explore this possibility. The
anomalous Hall effect in the well-ordered Co2TiSn films has been investigated
both experimentally and theoretically. The measured Hall conductivity is in
good agreement to the calculated Berry curvature. Small deviations between them
are due to the influence of skew scattering on the Hall effect. From
theoretical point of view, the main contribution to the anomalous Hall effect
originates from slightly gapped nodal lines, due to a symmetry reduction
induced by the magnetization. It has been found that only part of the nodal
lines contributed near to the anomalous Hall conductivity at a fixed Fermi
energy which can be explained from a magnetic symmetry analysis. Furthermore,
from hard x-ray photoelectron spectroscopy measurements, we establish the
electronic structure in the film that is comparable to the theoretical density
of states calculations. The present results provide deeper insight into the
spintronics from the prospect of topology.
