TEXTURED GROWTH OF STRONTIUM FERRITE THIN-FILMS BY SPUTTERING

Study of M-type hexagonal ferrite films (BaFe12O19 and SrFe12O19) is d rawing a lot of interest due to their potential applications. Ba ferri te films with perpendicular anisotropy have been studied due to their projected use in perpendicular recording media, magneto-optic recordin g media and in microwave/millimeter wave devices. The current interest in depositing these films with in plane anisotropy is for use in high density longitudinal recording media. There have been attempts to dep osit these materials, mostly on crystalline substrates though without complete control over the orientation. We have for the first time depo sited the sputtered strontium ferrite films and could vary the texture of the film to obtain both perpendicular and in plane anisotropy. It was found that the films prepared at lower rf power when annealed at t emperatures greater than or equal to 800 degrees C showed perpendicula r anisotropy while the films prepared with higher rf power after simil ar annealing showed in plane anisotropy. These films had been prepared without substrate heating during sputter deposition and the as deposi ted films were X-ray amorphous and were nonmagnetic. However, these 'a s deposited' films when annealed, showed different textures depending on the deposition conditions, as if these deposition conditions leave some signature in the films, which eventually decides the texture of t hese films. The microstructural studies showed that though the 'as dep osited' films were X-ray amorphous, oriented microcrystallites form du ring deposition, which could be controlling the texture at the time of complete crystallization during annealing.