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MM: Fachverband Metall- und Materialphysik
MM 63: Computational Materials Modelling - Phase Stability IV
MM 63.5: Talk
Thursday, March 14, 2013, 18:15–18:30, H24
Inverse magnetocaloric effect of epitaxial Ni-Mn-based films — •Anett Diestel1, Robert Niemann1,2, Maximilian Uhlmann1,2, Ludwig Schultz1,2, and Sebastian Fähler1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden, Germany — 2Dresden University of Technology, Institute of Materials Science, 01062 Dresden, Germany
The Heusler alloys Ni-Mn-X (X = Ga, In, Sn, Sb) have been identified as versatile functional materials. Due to the diffusionless phase transformation from austenite to martensite, which can be induced by magnetic field, the materials show the (inverse) magnetocaloric effect (MCE). They are promising materials for magnetocaloric cooling devices at room temperature application. Due to the high surface-to-volume ratio of thin films a fast heat exchange and a higher cycle frequency is possible. Therefore higher cooling efficiency can be achieved using less material compared to bulk. We prepared epitaxial Ni-Co-Mn-In [1] and Ni-Mn-Ga-Co films by magnetron sputter deposition on single crystalline MgO(100). For both materials we proved epitaxial growth and the reversible transformation from ferromagnetic austenite to modulated, non-ferromagnetic martensite. For Ni-Co-Mn-In an inverse MCE with an entropy change of 8.8 J/(kgK) at 9 T near room temperature was achieved.[1] By adding Co the martensitic transformation and the Curie temperatures can be shifted to maximize the inverse MCE at room temperature. The results show that epitaxial Ni-Mn-based films are promising materials for efficient magnetocaloric cooling devices. [1] R. Niemann et al. Appl. Phys. Lett. 97, 2010