Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 17: Magnetic Shape Memory Alloys
MA 17.10: Vortrag
Mittwoch, 28. März 2007, 17:30–17:45, H10
EPITAXIAL FILMS OF THE MAGNETIC SHAPE MEMORY MATERIAL Ni2MnGa — •Tobias Eichhorn, Gerhard Jakob, Michael Kallmayer, and Hans Joachim Elmers — Institute of Physics, Johannes Gutenberg University, 55099 Mainz
By dc-sputtering from a stoichiometric target onto sapphire and MgO substrates we prepared epitaxial films of Ni2MnGa. Using temperature dependend X-ray diffraction, resistivity and magnetization measurements we find the austenite to martensite transition in these films. The characteristic temperatures are shifted with respect to the bulk values. The presence of two different phases at high and low temperature also shows up in a different behavior of the magnetic hysteresis curves measured in the austenitic state and the martensitic state of the sample, respectively.
The element specific magnetic moments for thin film samples have been determined by magnetic circular x-ray dichroism (XMCD) measurements. From these measurements we determine orbital and spin momentum in austenite and martensite phase.
Changing target and film stoichiometry the martensitic transition temperature can be tuned to be above room temperature.