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MA: Fachverband Magnetismus
MA 15: Multiferroics II: Strain and Composites (jointly with DF, DS, KR, TT)
MA 15.1: Talk
Monday, March 14, 2011, 17:00–17:15, HSZ 04
Tuning magnetism by epitaxial strain in biferroic Fe70Pd30 films — •Sandra Weiss1, Markus Ernst Gruner2, Jörg Buschbeck1,3, Ludwig Schultz1, and Sebastian Fähler1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden — 2University of Duisburg-Essen, Theoretical Physics, Lotharstraße 1, D-47048 Duisburg — 3ECE Department, University of California, Santa Barbara
Due to combination of ferromagnetic and ferroelastic properties magnetic shape memory alloys can be considered as multiferrorics. For the magnetic shape memory alloy Fe-Pd we could demonstrate recently, that strained epitaxial film growth allows a variation of the tetragonal distortion by 27 % [J. Buschbeck et al., PRL 103, 2009, 216101]. Density functional calculations revealed a flat energy landscape along the Bain path, explaining this soft behaviour of Fe70Pd30. Here we show that tetragonal distortions up to 43 % are possible. This exceeds the Bain transformation path connecting bcc and fcc structure. Fe70Pd30 films are produced by coherent epitaxial growth on MgO substrates covered by different metallic buffer layers. By adjusting the tetragonal distortion intrinsic magnetic properties like Curie temperature, saturation magnetisation and magnetocrystalline anisotropy can be controlled. The relevance of two mechanisms for relaxation of epitaxial strain - misfit dislocations and adaptive martensite - is discussed.