Robust topological Hall effect in a reentrant spin glass system Mn 1.89 Pt 0.98 Ga 1.12

A Mn-vacancy polycrystalline tetragonal Heusler sample Mn 1.89 Pt 0.98 Ga 1.12 is fabricated in this work. The magnetic and AC-susceptibility measurements validate the existence of reentrant spin glass (RSG) state with the freezing temperature, T f  = 123 K in the alloy. Spontaneous exchange bias is also obtained with the maximum of ∼47 mT, which should be associated with the coexistence of ferrimagnetic matrix and spin-glass orderings. What's more, a robust and low field topological Hall effect (THE) is achieved in Mn 1.89 Pt 0.98 Ga 1.12, which is revealed by the hump-like anomaly in the field-dependent Hall resistivity curves. The maximum value of topological Hall resistivity is about 0.366 μΩ·cm at 5 K. This indicates that there may exist a non-coplanar spin configuration such as anti-skyrmion nucleating and annihilating with applying field, which contributes a non-zero scalar spin chirality. The mutual interplay among possible existence of anti-skyrmion, THE, and RSG in the alloy is discussed.