Peculiarity of topological Hall effect in Mn₂Sb_0.9Bi_0.1 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 ([Formula: see text]) is found before and after the SRT temperature TSR ∼260 K. Above the TSR, a positive [Formula: see text] is observed, e.g., ∼0.52 μΩ cm at 320 K. By reducing temperature to 275 K, the [Formula: see text] value decreases to ∼0.42 μΩ cm. It is interesting that, however, the negative [Formula: see text] 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.