Magnetic Anisotropy of Epitaxially Grown Fe/Mn/Co Trilayers

This paper reports a study of cubic magnetic anisotropies of bcc-Fe and bcc-Co structures in Fe/Mn/Co trilayers grown by molecular beam epitaxy onto MgO(001) substrates. Parallel ferromagnetic resonance experiments, at microwave frequency of 33.9 GHz, reveal the presence of a large fourfold magnetic anisotropy in all studied films. Two uniform resonance modes, with fourfold magnetic anisotropy in both bcc-Fe and Co layers, are excited by the microwave field in samples with Mn thicknesses of 0.83 and 0.99 nm. Films with thick Mn layer (1.16-2.20 nm) do not exhibit independent Fe and Co uniform modes, a result associated with an enhancement of the roughness at the Mn/Co interface (Fe/Mn interface roughness was estimated by ⁵⁷Fe Mössbauer spectroscopy to be nearly constant for all films) at the Fe/Mn and Mn/Co interfaces. Magnetic anisotropy constants of bcc-Fe and bcc-Co layers of sample with 0.99 nm thick Mn layer were determined, respectively, as 4.5×10⁵ and 6.4×10⁵ erg/cm³.