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

• DOI: 10.48550/arxiv.2304.03065
• Publication Date: 2023-01-01
• Authors: Eggert, Benedikt; Lill, Johanna; Günzing, Damian; Pillich, Cynthia; Terwey, Alexandra; Radulov, Ilyia A.; Wilhelm, Fabrice; Rogalev, Andrei; Rovezzi, Mauro; Skokov, Konstantin; Ollefs, Katharina; Gutfleisch, Oliver; Gruner, Markus E.; Wende, Heiko
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences

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.<br/>23 pages<br/>