Molecular beam epitaxial growth and properties of CoFe₂O₄ on MgO(0 0 1)

We have grown single-crystal Co ferrite (CoFe2O4) on MgO(0 0 1) by oxygen-plasma-assisted molecular beam epitaxy (OPA-MBE), and have characterized the composition, structure, surface morphology, and magnetic properties by a number of methods. The as-grown OPA-MBE material forms a perfect inverse spinel, in which all Co is in the 2+ formal oxidation state, and occupies octahedral sites within the cation sublattice. The OPA-MBE film surfaces are very flat, with mean roughnesses of only a few Å, and exhibit large, stable magnetic domains. The measured moment per unit volume is 250 emu/cm3, and the saturation magnetization for films in the 1000 Å film thickness range is ∼60% of that of bulk Co ferrite. The material also exhibits strain-dependent magnetic anisotropy that can be understood by considering the various contributions to the total magnetic energy. The overall quality of epitaxial Co ferrite grown on MgO by OPA-MBE is superior in every respect to that obtained using pulsed laser deposition as the growth method. © 2002 Published by Elsevier Science B.V.