Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 14: Multiferroics II (jointly with DF, DS, KR, MA)

TT 14.1: 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 Buschbeck^1,3, 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.