Preparation of short-period Fe-N magnetic multilayers using an atomic nitrogen beam

Magnetic multilayers containing Fe-N layers with bilayer periods of between ~15-84 Å and sharp interfaces, are successfully grown using an atomic (free radical) nitrogen beam. The phase composition and microstructure is found to be a function of the initial Fe layer thickness prior to nitrogenation. Generally, higher N content phases are found as the initial Fe layer is reduced. Small grains (~10 nm) are observed in multilayers containing α-Fe and γ-Fe₄N phases. In these films, a perpendicular anisotropy is found for a certain thickness of the Fe layers. A stripe domain structure associated with this anisotropy is observed. The origin of this anisotropy may be induced stress caused by lattice mismatch between layers and/or lattice dilation due to N incorporation