Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: Poster I (Bio- and Molecular Magnetism/ Magnetic Particles and Clusters/ Micro- and Nanostructured Magnetic Materials/ Magnetic Materials/ Multiferroics/ Magnetic Shape Memory Alloys/ Electron Theory of Magntism/ Spincaloric Transport/ Magnetic Coupling and Exchange Bias/ Magnetization Dynamics/ Micromagnetism and Computational Magnetics)

MA 19.69: Poster

Dienstag, 15. März 2011, 10:45–13:00, P2

Designing Heusler systems with martensitic transformations — •Ivan Titov, Mehmet Acet, and Eberhard Wassermann — Experimetalphysik, Universität Duisburg-Essen, 47048 Duisburg

The search for magnetic shape memory alloys as alternatives to the prototype Ni-Mn-Ga alloys system has provided further understanding of magnetic-field-induced effects in a variety of Ni-Mn-based martensitic Heusler alloys. Such alloys exhibit substantial antiferromagnetic exchange just below the martensitic transformation temperature, and this is thought to affect twin-boundary motion adversely since it can lead to pinning effects. We aim to find new Heusler materials that undergo martensitic transformations and, at the same time, are essentially free of antiferromagnetic exchange, or the exchange is sufficiently weak, so that twin-boundary motion is not hindered. These conditions primarily demand the alloy compositions to be Mn-free. Mn is the source of antiferromagnetic exchange, particularly at Mn-rich off-stoichiometric compositions. We present studies on the structural and magnetic properties of Co-Cr-Ga, Ni-(FeCr)-Ga, and Co-Ni-Fe-Ga and present an overview of their phase diagrams in relation to martensitic transformations.