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arXiv · 2304.03065

Local magnetic and geometric structure in Mn-doped La(Fe,Si)13

Benedikt Eggert·Johanna Lill·Damian Günzing·Cynthia Pillich·Alexandra Terwey·Ilyia A. Radulov·Fabrice Wilhelm·Andrei Rogalev·Mauro Rovezzi·Konstantin Skokov·Katharina Ollefs·Oliver Gutfleisch·Markus E. Gruner·Heiko Wende
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Abstract

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, and it is possible to tailor the phase transition towards room temperature by Mn-H-doping, resulting in a large temperature range for operation. Within this work, we discuss variations of the electronic and lattice structure in La(Fe,Si)$_{13}$ with increasing Mn content utilizing X-ray magnetic circular dichroism (XMCD) and extended X-ray absorption fine structure spectroscopy (EXAFS). While XMCD shows a decrease of the magnetic polarization at the Fe K edge, low-temperature EXAFS measurements indicate increased positional disorder in the La environment that is otherwise absent for Fe and Mn. First-principles calculations link the positional disorder to an enlarged Mn-Si distance -- explaining the increased positional disorder in the La surrounding.

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Benedikt Eggert, Johanna Lill, Damian Günzing, Cynthia Pillich, Alexandra Terwey, Ilyia A. Radulov, Fabrice Wilhelm, Andrei Rogalev, Mauro Rovezzi, Konstantin Skokov, Katharina Ollefs, Oliver Gutfleisch, Markus E. Gruner, Heiko Wende. 2023-04-06. Local magnetic and geometric structure in Mn-doped La(Fe,Si)13. https://arxiv.org/abs/2304.03065

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