Magnetic properties and corrosion-resistance of sputtered Co-Ni and Co-Ni-M films for longitudinal recording

The magnetic properties and corrosion resistance of sputtered Co-Ni/Cr and Co-Ni-M/Cr (M=Zr,Cr, Mo,Pt) thin films are investigated. Although pitting corrosion occurs on Co-Ni, Co-Ni-Mo, Co-Ni-Cr, and Co-Ni-Pt films for 1 mol/l NaCl spray tests, Co-Ni-Zr film exhibits almost no pitting because of total surface passivation. Furthermore, Co-Ni-Zr/Cr films show relatively high magnetization, high coercive force, and high squareness, which are suitable for longitudinal recording.