Magnetothermal and Magnetoelectric Transport Experiments in Mn1.8PtSnand Mn3Sn Thin Films

Richard Schlitz

The impact of non-trivial magnetic topology on the magnetoelectric and magnetothermaltransport response is actively studied at the moment. In particular, a large anomalous Halland Nernst effect can be observed in non-collinear antiferromagnets despite their vanishingnet magnetization [1,2]. Additionally, topological transport signals like the topological Hall andtopological Nernst effect can arise in the presence of non-trivial magnetic topology [3]. Suchtransport signatures allow accessing the microscopic properties of topological materials andwill be essential for exploiting the full potential of topological and antiferromagneticspintronics.I will first report on the observation of a large topological Hall and Nernst effect inmicropatterned thin films of Mn1.8PtSn below the spin reorientation temperature TSR ≈ 190 K.Our data can be used as a model system, allowing to calculate a so-called topologicalquantity. With this topological quantity, the detection of topological transport effects withoutthe need for independent magnetometry data is possible. Our approach opens the door forstudies of topological transport effects also in nanopatterned materials [4].In the second half of my talk, I will demonstrate the access to the local magnetic structure inthin films of the non-collinear antiferromagnet Mn3Sn by scanning thermal gradientmicroscopy (STGM). This technique is based on scanning a focused laser spot over thesample's surface and recording the ensuing thermo-voltage [5]. In addition to imaging theantiferromagnetic domain structure, STGM can also be used to prepare a definedantiferromagnetic magnetic domain state using a heat-assisted magnetic recording scheme,where local laser heating an magnetic fields are combined. Finally, I will address the impact ofthe hexagonal crystal symmetry of Mn3Sn on the STGM images of the local anomalousNernst effect.

[1] Nakatsuji et al., Nature 527, 212-215 (2015)
[2] Ikhlas et al., Nature Physics13, 1085-1090 (2017)
[3] Nagaosa et al., Reviews of Modern Physics 82, 1539 (2010)
[4] Schlitz et al., Nano Letters 19, 4, 2366-2370 (2019)
[5] Reichlova et al., Nature Communications 10, 5459 (2019)