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Coupling of Micromagnetic and Structural Properties Across the Martensite and Curie Temperatures in Miniaturized Ni-Mn-Ga Ferromagnetic Shape Memory Alloys

Authors

  • A. M. Jakob,

    1. Leibniz Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig, Germany
    2. Translationszentrum für Regenerative Medizin, Universität Leipzig, 04103 Leipzig Germany
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  • M. Hennes,

    1. Leibniz Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig, Germany
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  • M. Müller,

    1. Leibniz Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig, Germany
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  • D. Spemann,

    1. Nukleare Festkörperphysik, Fakultät für Physik und Geowissenschaften, Universität Leipzig, 04103 Leipzig, Germany
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  • S. G. Mayr

    Corresponding author
    1. Leibniz Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig, Germany
    2. Translationszentrum für Regenerative Medizin, Universität Leipzig, 04103 Leipzig Germany
    3. Fakultät für Physik und Geowissenschaften, Universität Leipzig, 04103 Leipzig, Germany
    • Leibniz Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig, Germany.
    Search for more papers by this author

Abstract

Micromagnetic structure evolution in Ni-Mn-Ga ferromagnetic shape memory thin films is investigated by means of temperature dependent magnetic force microscopy (TD-MFM). The center of interest is the magnetic properties of epitaxial Ni-Mn-Ga thin films on MgO substrates across thermally induced phase transitions. Experimental results are discussed within the framework of competing magnetic interactions arising in stressed thin ferromagnetic films. Measurements on 14M martensite specimens are supplemented by three-dimensional micromagnetic simulations. Corresponding calculated MFM micrographs are compared to experimental data. The influence of twin variant dimension and orientation on micromagnetic domain formation and wall structure is depicted from a theoretical point of view. A micromagnetic model system of partial flux closure is proposed and calculated analytically to estimate a stress induced magneto crystalline anisotropy constant in austenite Ni-Mn-Ga.

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