Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Caloric Effects in Ferromagnetic Materials

MA 10.1: Hauptvortrag

Montag, 20. März 2017, 15:00–15:30, HSZ 04

Magnetoelastic coupling and lattice dynamics in magnetocaloric materials — •Markus Ernst Gruner1, Werner Keune1, Michael Wolloch2, Peter Mohn2, Oliver Gutfleisch3, Heiko Wende1, and Rossitza Pentcheva11University of Duisburg-Essen — 2TU Vienna — 3TU Darmstadt

Solid state cooling concepts based on magnetocaloric materials offer an energy-efficient alternative to the conventional gas-compressor scheme. Large magnetocaloric effects are observed near magnetic first order transitions which involve a simultaneous change in volume or lattice symmetry and are subject to hysteresis losses. In metamagnetic Heusler alloys, lattice vibrations and magnetic order provide competing contributions to the entropy change, which further reduces the performance [1]. In metamagnetic FeRh [2] and conventional magnetocaloric La-Fe-Si-based compounds [3], lattice and magnetic degrees of freedom contribute cooperatively to the free energy. Comparing recent results from first-principles calculations and nuclear resonant inelastic X-ray scattering, we will review the relevant mechanisms for the favorable coupling of magnetism and lattice degrees of freedom in these two systems and discuss strategies to reduce the intrisic causes of hysteresis.
  Contributions from researchers of Argonne National Laboratory, the universities of Bochum, Darmstadt, Duisburg-Essen and Vienna, IFW Dresden, KIT and the SPP 1599 are gratefully acknowledged.
  [1] T. Gottschall et al., Phys. Rev. B 93, 184431(2016)
  [2] M. Wolloch et al., Phys. Rev. B 94, 174435 (2016)
  [3] M. E. Gruner et al. Phys. Rev. Lett. 114, 057202 (2015)

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