Soft magnetic properties of Co-Fe-Zr-B-Al-O films

We have investigated magnetic and electrical properties of amorphous Co-Fe-Zr-B alloy films with Al and O additions, deposited on rotating Si substrates by dc magnetron sputtering. Microstructural characterization carried out on these films shows the amorphous nature of films. The Co-Fe-Zr-B-Al-O films do not exhibit any uniaxial anisotropy in magnetization behavior in the as-deposited condition. However, a strong uniaxial anisotropy is introduced in the film plane by annealing at 200°C for 2 h and in an applied field of ∼150 Oe. The observed in-plane uniaxial anisotropy field (H _k) is as high as ∼38 Oe and the easy-axis coercivity is less than 1.5 Oe for the Co-Fe-Zr-B-Al-O film with 7 at.% Al. The ferromagnetic resonance frequency reaches a high value of ∼2.05 GHz, as a result of this large anisotropy field. It is also found that the soft magnetic properties of amorphous films have a strong dependence on the film composition. This is attributed to the change in the microstructure of films, which is closely related to the film composition.