CO, Ni_<80>Fe_<20>薄膜における強磁性共鳴の膜厚依存性  [in Japanese] Thickness Dependence of Ferromagnetic Resonance for Co and Ni_<80>Fe_<20> Thin Films  [in Japanese]

Thickness dependence of ferromagnetic resonance (FMR) and magnetic properties were studied for cobalt and Ni_<80>Fe_<20> thin films prepared on glass substrates by magnetron sputtering. Resonance field and linewidth increased with decreasing film thickness, while saturation magnetization and square ratio decreased. Thickness dependence of 4πM_<eff> estimated from resonance field by using Kittel's formula was consistent with 4πM_S from hysteresis loops. Linewidth was assumed to have two components: zero-frequency linewidth, ΔH_0, caused by magnetic inhomogeneities in films and viscous damping. ΔH_0 estimated from the experimental linewidth was, above 40Å thick, nearly constant with film thickness. Below 30Å, however, ΔH_0 for both films rapidly increased. These results were discussed by taking account of the structural inhomogeneity in the thin magnetic layer region.