Inferface Magnetization Phenomena in Epitaxial Thin Fe3O4/CoxFe3-xO4 Bilayers

In this work, we present a study about the chemical and magnetic properties of thin magnetite/cobalt ferrite bilayers deposited on MgO(001). Two series of samples with different CoxFe3-xO4 stoichiometries (x = 1 and x = 0.5) in combination with Fe3O4 layers of varying thickness were prepared by reactive molecular beam epitaxy. The quality of the respective films were controlled by means of in situ X-ray photelectron spectroscopy and low energy electron diffraction. Stoichiometry and electronic structure were carried out by hard X-ray photoelectron spectroscopy. To determine the cationic distribution and magnetic moments, X-ray magnetic circular dichroism measurements were performed and charge transfer multiplet and sum rule calculations were applied. Here we find an enhanced interface magnetization for the bilayers. Additionally, superconducting quantum interference device measurements showed characteristic exchange-spring behavior.