High frequency properties of Fe–Cr–Ta–N soft magnetic films

High frequency magnetic properties of a new, soft magnetic Fe–Cr–Ta–N alloy film have been investigated. Thin films with a composition of Fe-4.6% Cr-0.2% Ta-7.4% N (in atomic %) were prepared by reactive sputtering in a nitrogen-containing atmosphere. The films, most likely nanocrystalline, exhibit excellent soft magnetic properties in the as-deposited condition without any post heat treatment, e.g., $H_c$ as low as 1.2 Oe (95.3 A/m) and ${\text{4πM}}_s\text{∼20}$ kG. The easy-axis $\mathrm{M–H}$ loop is square. The hard-axis loop is linear and closed, with the anisotropy field $H_a\text{=20–100}$ Oe (1.59–7.95 kA/m). By virtue of their high ${\text{4πM}}_s$ and relatively high $H_a,$ these soft magnetic films exhibit high permeability and low loss in the GHz frequency range with the undesirable ferromagnetic resonance interference suppressed to beyond 2 GHz.