High moment FeTiN thin films for high density recording heads

High moment, soft FeTiN thin films were prepared by sputtering and the effects of film thickness, nitrogen concentration and annealing were investigated. It was found that a heated substrate helped to achieve a high moment and soft magnetic properties. Films thicker than 1500 Å deposited with no substrate heating always exhibited stripe domains, resulting in high values of the coercivity and the anisotropy field. Films deposited at elevated substrate temperatures did not have stripe domains for thickness up to 2000 Å. Films with high nitrogen concentration exhibited γ´-(Fe,Ti)₄N and ε-(Fe,Ti)_3-xN phases, resulting in low magnetization and higher coercivity. The annealing of films with low nitrogen concentration increased the magnetization, but the annealing of films with high nitrogen concentration induced a gradual phase change from the γ´-(Fe,Ti)₄N phase to the ε-(Fe,Ti)_3-xN phase, resulting in lower magnetization. Our experiments confirm the stabilization of the α´´-Fe₁₆ N₂ phase by incorporation of Ti, but we did not achieve the 24000 Gauss magnetization reported. Films with 5 at% nitrogen showed the highest moment (20000 Gauss) and best soft (H_C=3 Oe, H _K=7 Oe) properties. Annealing of (Fe₉₂Ti₈ )_1-xN_x (x=7.8 and 8.7) films deposited on glass at 130°C indicated that the anisotropy direction is not stable when annealed at 200°C for 2 h in a transverse magnetic field of 150 Oc