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MA: Fachverband Magnetismus
MA 18: Topical session: Caloric Effects in ferroic materials I - Magnetocalorics
MA 18.1: Talk
Tuesday, March 8, 2016, 10:15–10:45, H53
The coupling of electronic, magnetic and lattice degrees of freedom in the magnetocaloric system La-Fe-Si — •Markus E. Gruner1,2, Werner Keune1, Beatriz Roldan Cuenya3, Claudia Weis1, Joachim Landers1, Soma Salamon1, Benedikt Eggert1, Sergey I. Makarov1, David Klar1, Michael Y. Hu4, Ercan E. Alp4, Jiyong Zhao4, Maria Krautz5, Oliver Gutfleisch6, and Heiko Wende1 — 1Universität Duisburg-Essen — 2Forschungs-Neutronenquelle FRM II, Garching — 3Ruhr-Universität Bochum — 4Argonne National Laboratory — 5IFW Dresden — 6TU Darmstadt
LaFe13−xSix counts in its hydrogenated form as one of the most promising magnetocaloric materials for application. By combination of nuclear resonant inelastic X-ray scattering and first-principles calculations in the framework of density functional theory, we could recently demonstrate an unexpected phonon softening at the magnetic phase transition of pure La-Fe-Si, which contributes cooperatively with the magnetic degrees of freedom to the large magnetocaloric effect. The softening is traced back to
adiabatic electron phonon coupling which originates from specific changes in the electronic density of states at the Fermi Level due to the itinerant electron metamagnetism of Fe [1]. Within this contribution we will review the signatures of itinerant electron metamagnetism and its implication for the magnetoelastic coupling in pure, Mn-doped and hydrogenated La-Fe-Si. Funding by the DFG (SPP1599, TRR80) is gratefully acknowledged.
[1] M. E. Gruner, W. Keune, B. Roldan Cuenya et al.,
Phys. Rev. Lett. 114, 057202 (2015)