SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 42: Caloric Effects in Ferromagnetic Materials
MA 42.7: Vortrag
Donnerstag, 30. März 2023, 16:45–17:00, HSZ 04
The local magnetic and geometric structure in Mn-doped La(Fe,Si)13 — •Benedikt Eggert1, Johanna Lill1, Konstantin Skokov2, Cynthia Pillich1, Alexandra Terwey1, Fabrice Wilhelm3, Mauro Rovezzi3, Andrei Rogalev3, Katharina Ollefs1, Markus E. Gruner1, Oliver Gutfleisch2, and Heiko Wende1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen — 2Functional Materials, TU Darmstadt — 3European Synchrotron Radiation Facility
Magnetic cooling has the potential to replace conventional gas compression refrigeration. Materials such as La(Fe,Si)13 exhibit a sizeable first-order magnetocaloric effect. For Mn-H doped La(Fe,Si)13, it is possible to tailor the phase transition towards room temperature while maintaining first-order character. In this contribution, we discuss the effects of Mn-doping in La(Fe,Si)13 on the magnetic moments and the local environment by means of X-ray magnetic circular dichroism and extended X-ray absorption spectroscopy in the hard X-ray regime. Spectroscopic results indicate a reduction of the Fe magnetic moment and an increased structural disorder around the La site, which is not identified for the Fe sites. Furthermore, first-principles calculations reveal energetically unfavourable Mn-Si bonds that lead to a broad distribution of La-Si bond lengths that explain the experimentally observed structural disorder. We acknowledge the financial support through the Deutsche Forschungsgemeinschaft within the framework of the CRC/TRR 270 HoMMage and thank the ESRF for allocating beamtimes at ID12 and BM30.