Dresden 2017 – scientific programme
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MA: Fachverband Magnetismus
MA 67: Poster 4
MA 67.30: Poster
Friday, March 24, 2017, 09:30–13:00, P2-OG3
Structural characterization of multicaloric, epitaxial Ni-Mn-Ga-Co thin films on piezoelectric substrates — •Stefan Schwabe1,2, Benjamin Schleicher1, Robert Niemann1, Anja Waske1, Ruben Hühne1, Kornelius Nielsch1,2, and Sebastian Fähler1 — 1IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany. — 2TU Dresden, Institute of Materials Science, D-01069 Dresden, Germany.
Heusler alloys of the type Ni-Mn-Co-X (with X = Ga, In, Sb, Sn) are a promising material class for solid state cooling applications. They undergo a phase transition between the austenite at high and the martensite at lower temperatures accompanied by a reduction of crystal symmetry and the occurrence of an inverse magnetocaloric effect. This transformation can be influenced by the temperature, an applied magnetic field, but also mechanical stress. An epitaxial growth of thin films offers a well-defined orientation relation making it possible to model the structure of the twinned, low symmetry phase. Therefore, thin films were prepared on piezoelectric substrates and mechanically stressed by the application of an electric field. We present an investigation of Ni-Mn-Ga-Co thin films on piezoelectric PMN-PT substrates, which were grown epitaxially via sputter deposition. The structure of the martensite was probed with different X-ray diffraction methods, including 2D synchrotron XRD-measurements. The diffraction patterns are compared to calculated ones using the phenomenological martensite theory to examine the martensitic structure and influence of the stress. This work is supported by DFG through SPP 1599, www.FerroicCooling.de.