Structure and properties of the Mn doped CeO2 thin film grown on LaAlO3 (0 0 1) via a modified sol-gel spin-coating technique

Abstract

Here we report Mn doped cerium oxide films prepared on the LaAlO3 (0 0 1) substrate via an ethylene glycol modified sol-gel spin coating technique and evaluation of their properties as diluted magnetic semiconductors. Cerium oxide was selected because of its high dielectric constant and fluorite cubic structure, matching the silicon and lanthanum aluminate based electronic devices. The concentration of the Mn ions was varied from 1 to 13 at.% and the influence of this concentration on the structure, surface morphology, optical and magnetic properties of these films was studied using scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, ellipsometric spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and magnetic measurements. The incorporation of 7 at.% of Mn ions was found to provide formation of exceptionally smooth films, demonstrating the highest saturation magnetization of 1.75 μB/Mn and the coercive field of 487 Gauss. These properties are assigned to the conversion of Ce4+ to Ce3+ upon incorporation of Mn ions into the CeO2 structure and the oxidation of Mn2+ to Mn4+, creating two oxygen vacancies to preserve the cubic structure of cerium oxide and promoting ferromagnetism.