57Fe Mossbauer Study of Localization and Valence Sate of Iron Ions in Granular Nanocomposites (FeCoZr)x(Al2O3)100-x for Spintronic Applications

The influence of composition of the composite films, containing distributed fragmented components of amorphous metallic alloy CoFeZr and amorphous alumina with particles dimensions of 6 - 10 nm, on the Mossbauer spectra and hyperfine parameters was investigated. Mossbauer spectroscopy of the (Co0.45Fe0.45Zr0.10)X(Al2O3)1-X studied films with 30 at. % < X < 65 at. % has revealed that the structure of Fe ions coexisted in two valence states - Fe2+ and Fe3+, the pronounced tendency for increasing Fe3+ fraction with the X increment, disappearance of the singlet connected with the Fe - containing nanoparticles for the samples with X > 55 %, and lack of the ferromagnetic state in the metallic nanoparticles.