Abstract:From the point of view of application in the microwave band, the theoretic and experimental researches of nanostructural magnetic films were carried out. Micromagnetic structure of the nano-magnetic film was simulated by the finite element method. The typical micromagnetic was obtained. Corresponding experiments were also done aiming at the Co₄₀Fe₄₀B₂₀-SiO₂ nano-granular films. The results show that the characteristics of nano-magnetic film correspond with the micromagnetic ripple theory. The microwave permeability of nano-magnetic films deduces and well fits the Landau-Lifshitz-Gilbert (LLG) equation. The films present large microwave permeability and high resonant frequency (μ′ and μ″ at 2 GHz are about 100 and 40 respectively and the resonant frequency is about 2.8 GHz). The additional peak of μ″ originated from perpendicular anisotropy and micromagnetic ripple structure can be suppressed by the annealing process. Thus, the microwave complex permeability spectra of these nano-magnetic films can be tailored for different applications.

Key words: nano-granular film; random anisotropy model; micromagnetic simulation; ripple structure; microwave permeability