All Electrical Access to Topological Transport Features in Mn_1.8PtSn Films

Abstract

The presence of nontrivial magnetic topology can give rise to nonvanishing scalar spin chirality and consequently a topological Hall or Nernst effect. In turn, topological transport signals can serve as indicators for topological spin structures. This is particularly important in thin films or nanopatterned materials where the spin structure is not readily accessible. Conventionally, the topological response is determined by combining magnetotransport data with an independent magnetometry experiment. This approach is prone to introduce measurement artifacts. In this study, we report the observation of large topological Hall and Nernst effects in micropatterned thin films of Mn_1.8PtSn below the spin reorientation temperature T_SR ≈ 190 K. The magnitude of the topological Hall effect ρ_xy^T = 8 nΩm is close to the value reported in bulk Mn2PtSn, and the topological Nernst effect S_xy^T= 115 nV K^-1 measured in the same microstructure has a similar magnitude as reported for bulk MnGe ( S_xy^T ∼ 150 nV K^-1), the only other material where a topological Nernst was reported. We use our data as a model system to introduce a topological quantity, which allows one to detect the presence of topological transport effects without the need for independent magnetometry data. Our approach thus enables the study of topological transport also in nanopatterned materials without detrimental magnetization related limitations.