Large topological Hall effect in a non-coplanar ferromagnet Cr_0.9TeB_0.1

The Berry phase understanding of electronic properties has attracted special interest in condensed matter physics, leading to phenomena such as anomalous Hall effect (AHE) and topological Hall effect (THE). A non-zero Berry phase, induced by band structure in momentum space or non-coplanar spin structure is the origin of both effects. Here, we report a sign change in AHE and the origin of THE in Cr_0.9TeB_0.1 single crystal, due to a non-coplanar canted magnetic structure and the momentum space Berry curvature. At high temperatures, the moments are aligning ferromagnetically along the c axis, while non-coplanar canted magnetic structure is found below 140 K. The cone angle subtended by the spins depends on the temperature. This spin-reorientation leads to the change of Berry curvature, which influences both AHE and THE in the presence of an applied magnetic field and current. Our study provides a deep understanding of the relation between spin structure and Hall signal.