SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 42: Caloric Effects in Ferromagnetic Materials

MA 42.2: Vortrag

Donnerstag, 30. März 2023, 15:15–15:30, HSZ 04

Lattice contribution to entropy change at first-order phase transition in Laves phase DyCo₂ — •Johanna Lill¹, Benedikt Eggert¹, Jiyong Zhao², Benedikt Beckmann³, Barbara Lavina², Michael Hu², Konstantin Skokov³, Tom Toellner², Esen E. Alp², Katharina Ollefs¹, Oliver Gutfleisch³, and Heiko Wende¹ — ¹Faculty of Physics and CENIDE, University of Duisburg-Essen, Duisburg, Germany — ²APS, Lemont, Illinois - US — ³TU Darmstadt, Darmstadt, Germany

Laves phases are promising candidates for facilitating liquefaction, applying the magnetocaloric effect. The Laves phase of DyCo₂ undergoes a first-order phase transition around 140 K from a ferromagnetic (at low temperatures) to a disordered magnetic phase (at higher temperatures). The magnetic phase transition accompanies a structural change from cubic to tetragonal symmetry also resulting in a volume discontinuity. The magnetocaloric effect is a change in entropy along a phase transition, which in an adiabatically performed cooling cycle can lead to the desired cooling effect. This effect can be characterized by the amount of entropy change at the first-order phase transition. For magnetocaloric applications and improvement of reversible magnetocaloric effect it is therefore essential to understand the contributions of different subsystems to the overall entropy change. In this presentation, we show experimental data that resolves the Dy-partial lattice entropy of the DyCo₂ Laves phase along the first-order phase transition utilizing nuclear resonant inelastic x-ray scattering. We acknowledge financial support from DFG through TRR270 HoMMage.