Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 51: Magnetic Shape Memory Alloys (Joint Session with MM)
MA 51.10: Talk
Friday, March 20, 2015, 11:45–12:00, H 0112
Structure and Giant Inverse Magnetocaloric Effect of Epitaxial Ni-Co-Mn-Al Films — •Niclas Teichert1, Daniel Kucza1, Oguz Yildirim2,3, Ilker Dincer4, Anna Behler5, Lars Helmich1, Alexander Boehnke1, Anja Waske5, Yalcin Elerman4, and Andreas Hütten1 — 1Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Germany — 2Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf e.V., Germany — 3Dresden University of Technology, Germany — 4Ankara University, Department of Engineering Physics, Faculty of Engineering, Turkey — 5IFW Dresden, Institute for Complex Materials, Germany
The structural, magnetic, and magnetocaloric properties of epitaxial Ni-Co-Mn-Al thin films with different compositions have been studied. The films were deposited on MgO(001) substrates by co-sputtering on heated substrates. All films show a martensitic transition where the transition temperatures are strongly dependent on the composition. The structure of the martensite phase is shown to be 14M. The metamagnetic martensitic transition occurs from a strong ferromagnetic austenite to a weak magnetic martensite. The structural properties of the films were investigated by atomic force microscopy and temperature dependent X-ray diffraction. Magnetic and magnetocaloric properties were analyzed using temperature dependent and isothermal magnetization measurements. We find that Ni41Co10.4Mn34.8Al13.8 films show giant inverse magnetocaloric effects with magnetic entropy change of 5.8 J kg−1K−1 for µ0 Δ H=1 T.