Fabrication and characterization of micropillar-type multiferroic composite thin films by non-aqueous sol-gel method using ferroelectric pillars

CoFe2O4 (CFO) thin films were deposited on (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) micropillar films by a non-aqueous sol-gel method. The pitch size of 2-5 µm in the micropillar films used as ferroelectric pillars, and 5 and 15 CFO deposition cycles were examined for high density of CFO nanoparticles. All the CFO films formed by five deposition cycles on BNEuT micropillar films with a pitch size of 2-5 µm were composed of mostly single-phase CFO with a cubic inverse-spinel structure. All the CFO films deposited on the four BNEuT micropillar films were highly dense and had excellent surface flatness, based on surface FE-SEM observations. Based on the structural, magnetic and ferroelectric characteristics, the optimal pitch size for achieving a high density of CFO nanoparticles was 5 µm, and the optimal number of CFO deposition cycles was five.