Interfacial structure and chemistry of epitaxial CoFe2O4 thin films on SrTiO3 and MgO substrates
Abstract
Interfacial structure and chemistry of epitaxial CoFe2O4 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 CoFe2O4/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.
- Publication:
-
Applied Physics Letters
- Pub Date:
- November 2008
- DOI:
- Bibcode:
- 2008ApPhL..93r1901X
- Keywords:
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- 68.35.Ct;
- 82.65.+r;
- 75.50.Dd;
- 75.70.Ak;
- 79.20.Uv;
- 61.72.Ff;
- Interface structure and roughness;
- Surface and interface chemistry;
- heterogeneous catalysis at surfaces;
- Nonmetallic ferromagnetic materials;
- Magnetic properties of monolayers and thin films;
- Electron energy loss spectroscopy;
- Direct observation of dislocations and other defects