Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 46: Poster II
MA 46.86: Poster
Donnerstag, 21. März 2024, 15:00–18:00, Poster C
Anomalous Nernst effect in Ge-substituted iron nitride thin films — •Jakub Vit1, Petr Levinsky1, Kyo-Hoon Ahn1, Marketa Jarosova1, Imants Dirba2, and Karel Knizek1 — 1Institute of Physics, Czech Academy of Sciences, Prague, Czechia — 2TU Darmstadt, Germany
Iron nitrides – composed of abundant elements – have Curie temperatures (TC) well above the room temperature, below which they exhibit the anomalous Nernst effect (ANE) larger than pure iron. [1] Our recent DFT calculations suggested that the ANE may be further increased by substitution of other elements for iron. [2] Nevertheless, synthesis of such theoretically predicted compounds may be complicated. One of few successful syntheses of substituted iron nitrides is the case of Fe4−xGexN (x=0 – 1) antiperovskites, which were characterized in a form of powder. [3] We investigated the same compounds grown as epitaxial thin films, which provides convenient geometry for thermoelectric applications. Upon Ge-doping, TC expectedly decreases and the cubic structure becomes tetragonal. We measured magnetic properties, resistivity and the Nernst effect, the latter changing sign upon varying Ge content with comparable magnitude to Fe4N. This was reproduced in our DFT calculations when selecting the on-site Coulomb repulsion parameter U=1 eV, showing that finite U is necessary to use despite broad bands, typical for nitrides.
[1] S. Isogami et al., Appl. Phys. Express, 10, 073005 (2017)
[2] K.-H. Ahn et al., Phys. Rev. B, 108, 075123 (2023)
[3] T. Scholz and R. Dronskowski, J. Mater. Chem. C, 5, 166 (2017)
Keywords: anomalous Nernst effect; iron nitrides; thermoelectrics; thin films