  The direct liquid injection chemical vapor deposition (DLI-CVD) technique has
been used for the growth of cobalt ferrite (CFO) films on (100)-oriented
MgAl$_2$O$_4$ (MAO) substrates. Smooth and highly epitaxial cobalt ferrite thin
films, with the epitaxial relationship $\mathrm{MAO} (100)\:[001] \parallel
\mathrm{CFO} (100)\:[001]$, are obtained under optimized deposition conditions.
The films exhibit bulk-like structural and magnetic properties with an
out-of-plane lattice constant of $8.370\;\mathrm{\AA}$ and a saturation
magnetization of $420\;\mathrm{kA/m}$ at room temperature. The Raman spectra of
films on MgAl$_2$O$_4$ support the fact that the Fe$^{3+}$- and the
Co$^{2+}$-ions are distributed in an ordered fashion on the B-site of the
inverse spinel structure. The DLI-CVD technique has been extended for the
growth of smooth and highly oriented cobalt ferrite thin films on a variety of
other substrates, including MgO, and piezoelectric lead magnesium niobate-lead
titanate and lead zinc niobate-lead titanate substrates.
