Co-Ni-Fe Underlayer for Double-Layer Perpendicular Media

Co, whose vapour pressure is close to that of Ni and Fe, has been added to Ni-Fe system to get a lower coercive force Hc and a higher initial permeability ¿i for the fabrication process by web coating vacuum evaporation. A Co-Ni-Fe film 0.8 ¿m thick shows in-plane magnetic isotropy for all Co concentrations we investigated, and ¿i is three times as large as that of the binary Ni-Fe film when 15 to 30 wt% Co is added. These results show that the Co-Ni-Fe film in 0.8 ¿m thick prepared by the web coater vacuum evaporation system is appropriate for the underlayer of a double-layer perpendicular recording disk.