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Magnetooptical and magnetotransport effects in non-collinear antiferromagnets
Baďura, Antonín ; Schmoranzerová, Eva (advisor) ; Janda, Tomáš (referee)
In this thesis, we investigate the magnetic properties of an antiferromagnet Mn5Si3. Mn5Si3 shows two configurations of magnetic moments depending on temperature: the low-temperature phase (below 90 K) is noncollinear and noncoplanar, while the spin configuration is collinear at higher temperatures up to 240 K. Furthermore, the band structure of Mn5Si3 is spin-split in both antiferromagnetic phases via a specific nonrel- ativistic mechanism, referred as altermagnetism. We probed this spin-splitting by two distinct methods: Firstly, we characterized the transport properties of Mn5Si3 by mea- suring electronic and thermoelectric transport phenomena. Particularly, we detected the spontaneous Hall and Nernst responses in Mn5Si3 thin epitaxial films. The key outcome was a detailed analysis of the spontaneous Hall signal together with the observation of the spontaneous Nernst effect. In the second approach, we studied magnetooptical re- sponse of the thin films, where we focused on reflective geometry (the polar Kerr effect and the Voigt effect). We observed a pronounced signal in the Voigt geometry, which is quadratic in magnetization and could correspond to a magnetooptical signal. Further- more, we observed a change in optical response when the thin-film samples were exposed to a thermally-induced mechanical...
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