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

Abstract

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 (Hk) 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.