SKM 2021 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Posters Magnetism IV
MA 15.16: Poster
Donnerstag, 30. September 2021, 13:30–16:30, P
The local magnetic moment and vibrational properties of Sn in NiMnSn-Heusler alloys during magnetostructural phase transition — •Benedikt Eggert1, Benedikt Beckmann2, Johanna Lill1, Tobias Lojewski1, Simon Rauls1, Franziska Scheibel2, Andreas Taubel2, Olga Miroshkina1, Katharina Ollefs1, Richard Brand1, Michael Hu3, Markus Gruner1, Oliver Gutfleisch2, and Heiko Wende1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen — 2Functional Materials, TU Darmstadt — 3Argonne National Laboratory, USA
Materials with first-order magnetostructural phase transition exhibit a large magnetocaloric effect and may lead to environmentally friendly and more energy efficient alternative to conventional vapor compression refrigeration. The investigated NiMnSn Heusler alloy exhibits a first order phase transition from low temperature ferrimagnetic martensite to high temperature ferromagnetic austenite phase. We performed 119Sn nuclear resonant inelastic X-ray scattering (NRIXS) and 119Sn Mössbauer spectroscopy along the phase transition to track the evolution of lattice dynamics and the local magnetic moment, respectively, during this transition. Sn-NRIXS indicates variations in the phonon density of states that lead to a reduction of the Sn-selective vibrational entropy and a softening of the lattice in the austenite phase. On the other side, Sn-Mössbauer spectroscopy indicates an increase of the induced Sn-moment, showing that the magnetic structure changes. We acknowledge the financial support through the DFG (CRC/TRR270) and the U.S. DOE.