Interfacial structure and chemistry of epitaxial CoFe2O 4 thin films on (001)_SrTiO3 and (001)_MgO substrates were investigated using high-angle-annular-dark-field imaging combined with electron-energy-loss-spectra (EELSs) analyses at a subnanometer scale. The results show that CoFe2O4 / SrTiO3 interface is semicoherent with requisite dislocation density to accommodate ∼7% lattice mismatch, while the small (∼0.3%) lattice mismatch renders CoFe 2O4 /MgO interface coherent. EELS indicates that Fe valence is nominally +3, with no measurable change across the interfaces. Structural characterization corroborates with observed lower saturation magnetization of CoFe2O4 on MgO, which is a consequence of tensile stress built up in the 〈 100 〉 -direction negative magnetostrictive CoFe2O4.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)