Elektrický a tepelný magnetotransport v antiferomagnetických systémech

Martins Godinho, João Pedro

Title: Electro and thermal magnetotransport in antiferromagnetic systems Author: João Pedro Martins Godinho Abstract: How to electrically identify the Néel vector reversal in PT symmetric systems? The detection of magnetic order reversal has been one open problem in antifer- romagnetic spintronics. More so, in systems like the tetragonal CuMnAs which preserve the combined PT symmetry, since the combined PT symmetry renders odd magnetore- sistance effects such as the anomalous Hall effect to be zero. This thesis focuses on trying to provide an answer to the question above. We present the measurement of second- order magnetotransport effects as a mechanism to identify the reversal of the Néel order. We show it in two different systems, firstly on an out-of-plane synthetic antiferromagnet and later in the tetragonal CuMnAs. We also introduce a scanning thermal gradient microscopy which allows us to exploit different thermoelectric effects depending on the symmetries of the chosen material. For instance, in the collinear CuMnAs we take advan- tage of the magneto-Seebeck effect to image changes in the magnetic structure due to the application of electrical current pulses. In the case of the noncollinear antiferromagnetic Mn3Sn, the anomalous Nernst response is used to map the magnetic order. Keywords:...

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