Non-collinear antiferromagnets (NC-AFMs), new materials with non-collinear spin structure, offer a significant potential for spintronic applications [1]. They have vanishingly small magnetization and ultrafast spin dynamics. In addition, they allow for important counterparts to the effects considered to be exclusive to materials with net magnetization, such as the anomalous Hall effect (AHE) [2], magneto-optical Kerr effect [3] or anomalous Nernst effect (ANE) [4].

In this contribution, we will show our progress on both magneto-optical and magneto-transport in these systems. Particularly, we will discuss two types of materials: kagome-lattice antiferromagnet Mn3NiN , and a multi-sublattice antiferromagnet Mn5Si3. Both the systems share certain similarities in relatively weak spin orbit coupling, where the transport phenomena originate in Berry phase curvature of the band structure. However, while Mn3NiN is non-collinear in its low temperature AFM phase and ferrimagnetic above its Neel temperature [5]. Mn5Si changes its spin structure from the NC-AFM at low temperatures to collinear AFM at temperatures above roughly 90 K. The latter material belongs to the newly emerging class of “alter-magnets”, which display strong spontaneous Hall response, resulting solely from the Zeeman splitting [6,7].

We will present the results obtained using laser-scanning based experimental methods. The thermo transport response of the non-collinear antiferromagnets was investigated using scanning thermal gradient microscopy [4]. A laser beam incident on a micro-patterned device induces local thermal gradients. In materials with the thermo-electric response (such as Nernst or magneto-Seebeck effect), the thermal gradient translates into a transverse voltage, which enables to reveal domain structure of the particular material. Similarly, the domain structure can be explored using magneto-optical effects. We will show preliminary results on the study of the magneto-optical effects that are available in the non-collinear antiferromagnets.

[1] J. Železný, Y. Zhang, C. Felser, and B. Yan, Phys. Rev. Lett. 119, 187204 (2017).
[2] Nakatsuji, S., Kiyohara, N. & Higo, Nature 527, 212–215 (2015).
[3] T. Higo, et al. Nature Photon. 12, 73–78 (2018).
[4] H. Reichlová et al., Nat. Commun. 10, 5459 (2019).
[5] D. Boldrin et al., Phys. Rev. Materials 3, 094409 (2019).
[6] L. Šmejkal, J. Sinova, and T. Jungwirth: arXiv:2105.05820, 2021.
[7] H. Reichlova et al.: arXiv:2012.15651, 2020