High moment soft magnetic FeTiN thin films for recording head materials

Abstract

Soft magnetic properties and thermal stability of Fe–Ti–N alloys films have been investigated. Thin films with composition in the range of 8–10 at. % Ti, 10.5–14 at. % N, and balance Fe were prepared by reactive sputtering method. The films exhibit good soft magnetic properties in the as-deposited condition without any post heat treatment, e.g., low coercivity $H_c\text{∼1.5\hspace{0.05em}}\mathrm{Oe},$ high permeability $\text{μ∼3200}$ at 1 MHz and very high saturation magnetization ${\text{4πM}}_s\text{∼24\hspace{0.05em}}\mathrm{kG}.$ The thermal stability of these films was also found to be good, e.g., $H_c$ was less than 2 Oe, and ${\text{4πM}}_s$ was higher than 23 kG for the films annealed up to 500 °C. The high electrical resistivity $\text{ρ∼100\hspace{0.05em}μ\hspace{0.05em}Ω\hspace{0.05em}}\mathrm{cm}$ of the films can minimize the eddy current loss in the high frequency applications. The combination of high ${\text{4πM}}_s$ and relatively high anisotropy field $H_a\text{∼10\hspace{0.05em}}\mathrm{Oe}$ in the film is conductive to the suppression of the undesirable ferromagnetic resonance interfere up to the GHz frequency range.