Magnetic properties and reliabilities of FeXN (X=Ti,Al,Hf,CoHf,CrHf) nanocrystalline thin film head materials

A series of FeN and FeXN (X=Ti,Al,Hf,CoHf,CrHf) films were prepared by reactive RF magnetron sputtering. These FeXN films exhibit good soft magnetic properties with low coercivity (<2 Oe) and high moment (15-20 kG). To investigate the reliability of these films, we performed the thermal stability and electrochemical corrosion test for pure Fe, Permalloy, FeN and FeXN films. The results show that the direction of the magnetic anisotropy of FeTiN, FeCoHfN and FeCrHfN is not nearly changed by the DC magnetic field of 100 Oe perpendicular to the easy axis at 150°C, for up to 3 hrs. The electrochemical corrosion tests were performed in 0.5 M NaCl electrolyte. Permalloy shows the best corrosion resistance in the films but the addition of Cr to FeHfN films significantly improves the corrosion resistance, to be nearly as good as Permalloy. This improvement results from the formation of a negative oxide layer