The role played by interdiffusion in the molecular beam epitaxy of the binary Heusler alloy system Fe1-xSix/GaAs(001) was studied by using various complementary techniques that together provided some quantitative insight into the dynamics of the processes involved. The main properties of the investigated Fe0.84Si0.16 and Fe0.76Si0.24 films (growth, epitaxy, crystallographic order, interface quality, saturation magnetization, coercive field, magnetic anisotropy) were in perfect agreement with the literature. In addition, the results revealed strong interdiffusion of Fe and Si into the GaAs substrate as well as of As and Ga into the Fe1-xSix films, creating intermixed layers of 2 to 3nm in thickness in both film and substrate. Interdiffusion was dominant already at moderate growth temperatures required for crystallographic ordering, thus demanding new concepts including appropriate diffusion barriers for the development of ferromagnet/semiconductor hybrid systems.

Interdiffusion in Heusler Film Epitaxy on GaAs(001). C.Gusenbauer, T.Ashraf, J.Stangl, G.Hesser, T.Plach, A.Meingast, G.Kothleitner, R.Koch: Physical Review B, 2011, 83[3], 035319