Ferromagnetism and Morphology of Annealed Fe₂O₃/Co_XO_Y/ZnO Thin Films

Abstract

We have studied thermal solid‐state reactions in the Fe2O3/CoXOY/ZnO thin film systems grown using the atomic layer deposition technique. The compound produced after annealing at 700 °C is found to be a complex mixture of three different spinel phases: ZnCo2O4, CoFe2O4, and ZnFe2O4. The magnetic properties of the compound strongly depend on the atomic ratio of Fe3+ and Co2+ atoms, which can be set by choosing the corresponding thicknesses of the Fe2O3 and CoXOY films. In addition, we also find a formation of 100 nm voids at the interface between Fe–Co–Zn–O compound and remaining ZnO film after 1h annealing at 700 °C in argon atmosphere. The formation of these voids shows indirectly the preferential outward diffusion of Zn2+ ions from ZnO into the Fe2CoO4 phase layer what we prove via our magnetic measurements.