FMR and Magnetization Study of ZnFe2O4 Nanoparticles in 0.40Fe2O3/0.60ZnO Nanocomposite

Zinc oxide (ZnO) nanocrystals containing Fe₂O₃ have been synthesized by the calcination method. Ferromagnetic resonance (FMR) and dc magnetization measurements of 0.40(Fe₂O₃)/0.60(ZnO) nanocomposite have been carried out in the 4-300 K range to study the magnetic properties of agglomerated magnetic zinc ferrite ZnFe₂O₄ (ZFO) nanoparticles with an average crystallite size of 12 nm. Temperature dependence of the resonance field, linewidth, and the integrated intensity calculated from FMR spectra have been determined to obtain the value of the uniaxial anisotropy field and to establish the ranges of different relaxation types. Magnetization measurements in ZFC and FC modes as well as the study of hysteresis loops allowed calculating different magnetic characteristics - blocking/freezing temperature, magnetic moment, anisotropy constant, and anisotropy field. The observed magnetic properties of 0.40(Fe₂O₃)/0.60(ZnO) nanocomposite were explained based on the core-shell model of ZFO nanoparticles. From comparison of FMR and dc magnetization measurements, the temperature ranges of magnetic phases existing in ZFO nanoparticles in 0.40Fe₂O₃/0.60ZnO nanocomposite are proposed.