Topological Hall Effect in (Mn_1-xFe_x)_3.25Ge (x=0.4) Hexagonal Magnet

Topologically protected nontrivial spin structures attract significant interest in condensed matter physics for their utilization in low-power-consumption spintronics devices, memory devices, etc. The topological Hall effect (THE) is an additional Hall resistivity in the system arising from real-space Berry curvature picked up by conduction electron passing through the nontrivial spin texture. Compared to expensive neutron diffraction measurements, THE is often used as a cost-effective tool to investigate nontrivial spin texture in the materials. In the present manuscript, THE in the (Mn1-xFex)(3.25)Ge (x = 0.4) alloy is studied using magneto-transport measurements. Maximum THE is found in the system about 0.65 & mu;& omega; cm at 150 K, which is in contrast to the pristine Mn3Ge that has zero THE. The strong temperature variation of THE suggests that the noncoplanar spin structure due to competition among the magneto-crystalline anisotropy, antiferromagnetic coupling, and ferromagnetic exchange interaction is the main source of THE in the present system. Herein, it is shown that chemical doping can be an effective way to induce THE in the material with vanishing THE in its parent phase.