Development of NanoCAP technology for high-density recording

For high-density recording tape, NanoCAP was developed using co-precipitation and nitridation treatment in an NH/sub 3/ gas atmosphere. Each particle has a spherical shape with a diameter of about 17 nm and a core-shell structure. The core and shell mainly consist of the Fe/sub 16/N/sub 2/ and oxides containing Al and Y, respectively. The saturation magnetization and the coercive force are 85.5 A/spl middot/m/sup 2//kg (85.5emu/g) and 227 kA/m (2850 Oe), respectively. The coercive force is a higher value that of the needle-shaped particles currently used and is stable from room temperature to 323 K. The higher coercive force originates from an uniaxial magnetic anisotropy of the Fe/sub 16/N/sub 2/.