Large topological Hall effect in Ti-doped Mn2-xTixSb (0 < x ≤ 0.2) ferrimagnets

Very recently, large and novel topological Hall effect (THE) has been reported near spin reorientation transition (SRT) in Mn₂Sb-based ferrimagnets, which are in general believed as a category of multiple magnetic functional materials. In this work, the structure, microstructure, and electrical transport properties are investigated in Ti-doped Mn_2-xTi_xSb (0 < x ≤ 0.2) polycrystalline alloys. Firstly, it is amazing to find that the inevitable MnSb impurity takes on many nearly straight, long and narrow bands, which wraps around the perimeter of Mn₂Sb main phase. With increasing Ti-substitution, the MnSb impurity is becoming less and less. For all the samples, secondly, the antiferromagnetic (AFM) state and accordingly the first-order AFM-ferrimagnetic (FIM) transition is not discovered. Evidently, nevertheless, the spin reorientation transition (SRT) temperature T_SR declines. What is more important, a large positive topological Hall resistivity (${\rho }_{\mathrm{xy}}^T$) ∼0.84 μΩ cm is gained at 1.8 mT and 260 K in Mn_1.88Ti_0.12Sb alloy. At the same time, a sign switching of ${\rho }_{\mathrm{xy}}^T$ is strikingly observed before and after the SRT. With ascending Ti-content from 0.12 to 0.20, furthermore, it is found that the positive value of ${\rho }_{\mathrm{xy}}^T$ increases firstly and then diminishes around SRT. The physical mechanism behind these phenomena is discussed in polycrystalline Mn_2-xTi_xSb (0 < x ≤ 0.2) alloys.