Magnetic properties, microstructures, and corrosion resistance of high-saturation FeMoN and FeRhN films for recording heads

We have investigated high-saturation FeMoN and FeRhN films, deposited by radio frequency-diode reactive sputtering on alumina-TiC substrates, for inductive head applications. A minimum coercivity of ~1.2 Oe is obtained in (Fe_97.8Mo_2.2)N films at a N ₂/Ar flow ratio of ~6.2%. A minimum coercivity of ~1.6 Oe is obtained in (Fe_96.9Rh_3.1)N films at a N₂/Ar flow ratio of ~4.6%. The films mainly consist of α-Fe phase and γ´-Fe₄N phase; The magnetic properties of these films are stable under easy axis field annealing up to 350°C. Addition of Rh or Mo to FeN has resulted in a significant improvement in corrosion resistance over that of FeN. The localized corrosion resistance of FeRhN and FeMoN can be comparable to that of Permalloy. In contrast, their intrinsic corrosion resistance is inferior to that of Permalloy, but it can be adjusted and controlled by pH level