Sputtered hexagonal Ba-ferrite films for high-density magnetic recording media

Ba-ferrite (BaM) thin films were prepared by both a facing targets sputtering (FTS) system and dc magnetron sputtering (DCMS) at room temperature. They were successively annealed to crystallize. The films prepared by FTS system were crystallized at 650 °C, while those prepared by DCMS system were crystallized at 700 °C. Saturation magnetization, coercivity, and squareness ratio of the films prepared by FTS are 210 emu/cc, 3.3 kOe, and 0.7 in perpendicular direction, respectively, after the annealing at 650 °C. It was found that oxidized Fe is partially reduced to metallic Fe by high-temperature annealing.