Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 53: Joint Session Magnetic Shape Memory Alloys II (jointly with DS, MA)

MM 53.5: Vortrag

Donnerstag, 29. März 2012, 16:00–16:15, H 0112

Effect of the film thickness on the martensitic transformation in Ni-Mn-Sn ultra-thin films — •Niclas Teichert, Alexander Auge, and Andreas Hütten — Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld

Off-stoichiometric Ni-Mn-Sn is a ferromagnetic shape memory alloy (FSMA) in certain Mn-rich compositions. The studied alloy shows a phase transformation during cooling from a cubic high temperature austenite phase to a martensite phase with lower symmetry. Subsequent heating leads to the inverse transformation back to austenite. We have produced highly epitaxial Ni_51.6Mn_32.9Sn_15.5 thin films of thicknesses between 200 nm and 20 nm on MgO substrates via co-sputtering. The dependency of the martensitic transition on the film thickness was determined by conductivity and anomalous Hall effect (AHE) measurements in the temperature range between 20 K and 340 K. These measurements give us information about the transformation characteristics such as transition temperatures, temperature dependent saturation magnetization and the amount of transforming material for the different films. The AHE is used to analyze the scattering mechanisms during the transformation.