Realization of epitaxial barium ferrite films of high crystalline quality with small resonance losses

We report the results of systematic studies of the effect of thin film deposition conditions, such as deposition temperature, oxygen pressure during deposition, etc., on the microstructural, magnetic, and microwave properties of pulsed laser deposited epitaxial thin films of barium ferrite on single crystal sapphire substrates. Ferromagnetic resonance (FMR) linewidths are very sensitive to the presence of defects and inhomogeneities and therefore change markedly with the variation of deposition parameters. After careful optimization of the deposition conditions, relatively narrow resonance lines were realized in these films. For further improvement in the film quality, these films were annealed at elevated temperatures in flowing oxygen. As a result of the high degree of epitaxy, good stoichiometry, and reduced concentration of defects, FMR linewidths as small as 37 Oe were obtained in films deposited at 920°C and subsequently annealed at 1000°C in an oxygen atmosphere.