Preparation and characterization of thin films of M-type barium ferrite on microcrystalline carbon substrates with diffusion barrier sublayers

Hexagonal barium ferrite films have been grown on microcrystalline carbon substrates for the first time and thermally oxidized SiO2/Si wafers using dc facing targets sputtering. Si3N4 and SiO2/Cr underlayers were effective in preventing carbon diffusion into the barium ferrite films during deposition at high temperatures (550–600 °C). X-ray diffraction spectra showed that the c axis of the crystals are perpendicular to the film surface. The dispersion of the c axis (Δθ50) was 2.5°. The perpendicular coercivity varied from 860 to 1200 Oe and the saturation magnetization (Ms) was about 300 emu/cm3. The delta M curves were negative in the in-plane direction and positive in perpendicular directions.