Interlayer diffusion studies of a Laves phase exchange spring superlattice

Rare earth Laves phase (RFe₂) superlattice structures grown at different temperatures are studied using x-ray reflectivity (XRR), x-ray diffraction, and transmission electron microscopy. The optimized molecular beam epitaxy growth condition is matched with the XRR simulation, showing minimum diffusion/roughness at the interfaces. Electron microscopy characterization reveals that the epitaxial growth develops from initial 3D islands to a high quality superlattice structure. Under this optimum growth condition, chemical analysis by electron energy loss spectroscopy with high spatial resolution is used to study the interface. The analysis shows that the interface roughness is between 0.6 and 0.8nm and there is no significant interlayer diffusion. The locally sharp interface found in this work explains the success of simple structural models in predicting the magnetic reversal behavior of Laves exchange spring superlattices.