Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 35: Caloric effects in ferromagnetic materials
MA 35.2: Vortrag
Mittwoch, 3. April 2019, 15:15–15:30, H52
Unraveling the role of hydrogen on the vibrational and magnetic properties of LaFe13−xSixHy — •Markus E. Gruner1, Alexandra Terwey1, Joachim Landers1, Soma Salamon1, Werner Keune1, Katharina Ollefs1, Valentin Brabänder2, Iliya Radulov2, Konstantin Skokov2, Jiyong Zhao3, Michael Y. Hu3, Thomas S. Toellner3, Ercan E. Alp3, Oliver Gutfleisch2, and Heiko Wende1 — 1Universität Duisburg-Essen — 2TU Darmstadt — 3Argonne National Laboratory
LaFe13−xSix is one of the most promising candidates for magnetic
refrigeration applications. Its favorable first-order magnetic transition is connected to the itinerant electron
metamagnetism of Fe, while loading with hydrogen allows to shift TC to ambient conditions.
To avoid decomposition into low- and high-TC regions, full loading is mandatory, which occupies only a part of the (24d) interstitial sites.
Our density functional theory (DFT) calculations reveal that hydrogen strongly disfavors the presence of Si close to the interstitial sites.
By combining DFT and nuclear resonant inelastic X-ray scattering (NRIXS), we identify
adiabatic electron-phonon coupling as the microscopic mechanism causing the beneficial cooperative interplay
between electronic, magnetic and vibrational degrees of freedom in LaFe13−xSixHy.
In addition, we discuss the impact of interstitial hydrogen on the magnetic interactions between the different Fe sites
and give an oulook on the impact of a partial substitution of Fe with other transition metals
on the vibrational properties.
Funding by the DFG within SPP 1599 is gratefully acknowledged.