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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.