Electrical transport in FIB-microstructures of single-crystalline Mn_1.4PtSn

Mn_1.4PtSn is a half-Heusler compound with tetragonal crystal structure that hosts a D2d symmetry and strong Dzyaloshinskii-Moriya interactions. These are key-ingredients for the possible presence of Antiskyrmion phases. Recently, Antiskyrmions were observed well above room temperature by Lorentz transmission microscopy (LTEM) in polycrystalline nanoscaled ingots of the material [1]. Such a magnetic texture may cause a topological Hall effect (THE) leading to a significant deviation from the expected anomalous Hall effect. Indeed, a topological component of high magnitude was revealed by Hall measurements, conducted on bulk single crystals [2]. It however, only was observed below the spinreorientation transition at T_SR = 160 K associated with the formation of a non-coplanar spin structure. We investigate transport devices fabricated by the application of focused ion beams (FIB) from high-quality single crystals. Assisted by FIB we are able to conduct experiments on devices with sub-micron feature sizes. Our study of the temperature, field, and thickness dependent transport reveals clear signatures of THE originating from both, the non-coplanar spin structure as well as Antikyrmions, with apparent differences.
[1] Nayak et al., Nature 548 (2017) [2] Vir et al., PRB 99 (2019)