Influence of Interlayer Thickness on High-Frequency Magnetic Properties of FeCoSiN/AlO/FeCoSiN Trilayers

In this paper, we investigate the static magnetic properties and high-frequency permeability spectra of as-sputtered FeCoSiN/AlO/FeCoSiN trilayer films and discuss their dependences on the thickness of AlO interlayer, based on the phenomenological Landau-Lifshitz-Gilbert equation. The hysteresis loops show that the interlayer effectively decreases the coercivities of trilayers in the thickness range between 3 and 10 nm. The effective anisotropy field obtained from the fitting of permeability spectra increases with the interlayer thickness to saturation. The dependence of damping factor on the interlayer thickness has a maximum. It is attributed to the Néel couplings at the thicker interlayer range and the strong ferromagnetic couplings at the thinner interlayer range.