Investigation of ferromagnetic resonance and damping properties of CoFeB

In this study, the influences of thin film thickness and post-annealing process on the magnetic properties of CoFeB thin films were investigated. The angular dependency and linewidth of the ferromagnetic resonance signal were used to explore the magnetic behavior of sputtered single-layer and trilayer thin film stacks of CoFeB. A micromagnetic simulation model was employed based on the metropolis algorithm comprising the demagnetizing field and in-plane induced uniaxial anisotropy terms with all relevant contributions. Our results reveal that the direction of magnetization changes from in-plane to out-of-plane as a result of the annealing process and induces a perpendicular magnetic anisotropy in the 1-nm thick CoFeB thin film. The ferromagnetic resonance (FMR) linewidth can be defined well by the intrinsic Gilbert damping effect and the magnetic inhomogeneity contribution in both as-grown and annealed samples. The difference between the linewidths of the single and trilayer film is mainly caused by the spin pumping effect on damping which is associated with the interface layers. •The effect of CoFeB layer thickness on magnetization and linewidth were reported by using FMR technique.•Micromagnetic simulation model was used for finding of magnetic parameters of the samples.•The magnetic anisotropy and line width changed as a result of the interlayer diffusion with the annealing treatment.•After the post annealing process, Gilbert field dragging became the dominant contribution to linewidth.•The difference between the linewidths of the single and trilayer systems was observed by the spin pumping effect on damping.