Peculiarity of Topological Hall Effect in Mn2Sb0.9Bi0.1 Ferrimagnet

The substituted Mn2Sb-based ferrimagnetic (FIM) alloys by other elements have attracted much attention recently due to excellent magneto-functional properties. However, almost all investigations have been concentrated on the first-order phase transition between antiferromagnetic and FIM state. In this work, a large topological Hall effect (THE) associated with the spin reorientation transition is observed in the Mn2Sb0.9Bi0.1 alloy. Strikingly, the sign reversal of topological Hall resistivity (ρxyT) is found before and after the SRT temperature TSR ∼260 K. Above the TSR, a positive ρxyT is observed, e.g., ∼0.52 μΩ cm at 320 K. By reducing temperature to 275 K, the ρxyT value decreases to ∼0.42 μΩ cm. It is interesting that, however, the negative ρxyT value is found below the TSR, e.g., ∼−0.66 μΩ cm at 175 K. The physical mechanism about this peculiar THE is discussed in Bi-doped Mn2Sb-based alloys.