Inferface Magnetization Phenomena in Epitaxial Thin Fe₃O₄/Co_xFe_3–xO₄ Bilayers

Abstract

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 Co x Fe 3−x O 4 stoichiometries (x = 1 and x = 0.5) in combination with Fe 3 O 4 layers of varying thickness were prepared by reactive molecular beam epitaxy. The quality of the respective films were controlled by means of in situ Xray 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.

Development of in situ characterization techniques in molecular beam epitaxy

“…By directing lower energy electrons onto a surface and measuring their diffraction pattern on a fluorescent screen, LEED can determine the surface structure of the sample and characterize crystallinity, surface relaxation, and the reconstruction of adsorbate-covered surfaces [84, 98−101] . Researchers, such as Zhang et al, have combined LEED patterns with density functional theory calculation to study the relationship between structural transitions and substrate temperature for depositing coronene monolayers on Cu(110) surfaces [102] . By calculating the temperature dependence of free energy, they explained the irreversible transition and the stable state determined by the LEED patterns shown in Fig.…”