Magnetic properties and high-frequency characteristics of FeCoAlO gradient composition thin films

5 25 mm FeCoAlO gradient composition thin film was prepared with composite target by using RF magnetron sputtering. The Al-O composition gradient along the length direction of the film was introduced by Al O chips asymmetrically arrayed on a Fe Co target disk. The film was divided into five equal segments. All samples showed a low coercive force H of 4 - 8 Oe. The saturation magnetization 4M increased continuously from 17.3 kGs for sample 1 (has more Al-O content) to 19.7 kGs for sample 5 and it was consistent with the increasing of Fe-Co composition. Meanwhile, these samples showed different anisotropy behaviors relating with Al-O composition. The sample 1 exhibited the same magnetization curve along the directions of G and G (G and G are parallel and perpendicular to the direction of the Al-O composition gradient, respectively). In both of G G directions, the sample 1 showed a resonance frequency (f ) of around 2.6 - 3.0 GHz, while, in G direction, it showed a high value of real permeability μ′. The sample 5 exhibited a distinct in-plane uniaxial anisotropy and a good high-frequency response of 3.0 GHz resonance frequency. So these films having gradient composition exhibit are suggested for the use in integrated magnetic devices working in the GHz frequency range. © 2012 American Institute of Physics.