Dresden 2009 – scientific programme
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MA: Fachverband Magnetismus
MA 21: Magnetic Shape Memory Alloys I
MA 21.6: Talk
Wednesday, March 25, 2009, 11:30–11:45, HSZ 103
Magnetic control of twinning structure in thin Ni2MnGa films — •Tobias Eichhorn1, Catherine Anne Jenkins2, Michael Kallmayer1, Hans-Joachim Elmers1, Gerhard Jakob1, and Michael Huth3 — 1Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany — 2Department of Materials Science and Engineering, University of California, Berkeley, 94720, USA — 3Physikalisches Institut, Goethe-Universität Frankfurt, 60438 Frankfurt/Main, Germany
We report on the preparation and investigation of thin epitaxial films of the ferromagnetic shape memory alloy Ni2MnGa. Sample preparation is done by dc-magnetron sputtering from different NiMnGa targets onto heated substrates. The orientation of the film can be tailored by selecting different substrates. The complex crystal structure is studied by temperature-dependent x-ray diffraction in 4-circle geometry. Magnetometry measurements reveal the martenistic transformation that is crucial for the appearance of magnetically induced shape changes. To get insight on microscopic magnetism and electronic structure x-ray absorption spectroscopy and magnetic circular dichroism measurements have been performed at the German synchrotron light source BESSY II (Berlin). Free-standing films that will be needed for technical applications have been prepared using water-soluble NaCl substrates. Another approach is the fabrication of free-standing cantilevers that allow the observation of magnetically induced changes in the microstructure. This work is part of the priority program SPP 1239 and founded by the DFG.