Ferromagnetic resonance spectroscopy of CoFeZr-Al2O3 granular films containing “FeCo core – oxide shell” nanoparticles

• CoFeZr-Al2O3 granular films containing “FeCo core – oxide shell” nanoparticles.
• magnetic anisotropy of (CoFeZr)x(Al2O3)100−x films is of an easy plane type.
• essential difference in dependence of g-factor on metal content in non- and oxidized film.
• non-oxidized samples indicates the reduction of the value of films magnetization.

Ferromagnetic resonance (FMR) spectroscopy is applied for comparative analysis of granular (CoFeZ)x(Al2O3)100−x, (31 at%≤x≤47 at%) films containing pure FeCo-based nanoparticles (NPs) or “FeCo-based core – oxide shell” NPs inside Al2O3 matrix when deposited in oxygen-free or oxygen-containing atmosphere, correspondingly. It is established that g-factor extracted from the FMR spectra of films with core–shell NPs decreases with x below the value g =2.0023 for free electron that is untypical for metallic NPs. This effect is associated with the formation of the interface between ferromagnetic core and antiferromagnetic (ferrimagnetic) oxide shell of NPs.