Influence of local anisotropy fluctuation on soft magnetic properties of the sputtered Fe-Si-Al alloy films

Effective permeability, μ_eff, uniaxial anisotropy field, H_k, and local anisotropy fluctuation represented as magnetic ripple, SA^-5/8 (S is the structure constant and A^-5/8 is a coefficient equal to the power of the exchanges stiffness constant), were systematically studied as a function of composition and film thickness for Fe-Si-Al ternary alloy films. The influence of H_k and SA^-5/8 on μ_eff is discussed in connection with the film structure. The magnitude of μ_eff was found to depend strongly on the magnitude of microscopic local anisotropy fluctuation. A decrease of the film thickness caused a marked increment in SA^-5/8 due to the change of the preferred grain orientation from (110) to (110)+(100) texture. To realize high μ_eff for Fe-Si-Al films in the high-frequency region, it is concluded that a homogeneous preferred grain orientation is important