Phase identification of cobalt ferrite/metal composite thin films using convergent beam electron diffraction

Cobalt ferrite/metal composite thin films with a saturation magnetization (M_s) of ∼0.729 Weber m^-2 were prepared by a reactive sputtering method. The M_s of the thin films increased with increasing substrate temperature. The microstructures of the thin films were identified by a convergent beam electron diffraction method. For the thin films deposited at high substrate temperatures (> 300 °C), Co_xFe_1-x (x ≈ 0.62) metal alloys were separated from the cobalt ferrite matrix. A cobalt ferrite phase was determined as CoFe₂O₄ with a cubic structure (a₀=0.839 nm) and a space group of Fd3m, while a metal phase Co_xFe_1-x (x ≈ 0.62) with a b.c.c. structure (a ₀=0.289 nm) and a space group of Im3m.