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MM: Fachverband Metall- und Materialphysik

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

MM 53.4: Vortrag

Donnerstag, 29. März 2012, 15:45–16:00, H 0112

Element-specific temperature dependence of the Ni and Mn magnetization in Ni_51.6Mn_32.9Sn_15.5 — •Bernhard Krumme¹, Alexander Auge², David Klar¹, Frank Stromberg¹, Andreas Hütten², and Heiko Wende¹ — ¹Faculty of Physics and CeNIDE, University of Duisburg-Essen, D-47048 Duisburg, Germany — ²Thin Films and Nanostructures, Department of Physics, University of Bielefeld, D-44801 Bielefeld, Germany

Off-stochiometric compositions of the Heusler compound Ni₂MnSn with an increased content of Mn are known to be ferromagnetic shape memory alloys (FSMA). This class of materials shows a structural phase transition influencing the magnetization as well as the electric resistivity. Therefore, such materials are of interest for applications, e.g. as actuators. We investigated the influence of the structural phase transition on the element-specific magnetization and electronic structure of Ni and Mn in Ni_51.6Mn_32.9Sn_15.5 by means of X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). Due to the element-specificity we were able to reveal a different temperature dependence of the ratio of orbital to spin magnetic moment of Mn compared to Ni. In parallel a change of the electronic structure of Mn is observed, whereas for Ni almost no modifications occur. By applying a magnetic field of 3T in the martensite phase it is possible to reduce the ratio of orbital to spin magnetic moments indicating a field induced reverse martensitic transition (FIRMT).

– Supported by DFG (SFB 491) and SOLEIL, Paris.