Investigations of surface spin canting in Ni-Zn nanoferrite and its development as magnetic core for microwave applications

Abstract

• Achieved high saturation magnetization of 80.3 emu/gm for a crystallite size of 42 nm. • Low surface spin canting angle observed is the cause for such high magnetization. • Initial permeability dispersion shows that the material would be suitable as magnetic core up to 18 GHz. Nanoparticles of nickel zinc ferrite Ni 0.65 Zn 0.35 Fe 2 O 4 having an average crystallite size of 42 nm, synthesized by sol–gel method were found to exhibit the highest value of saturation magnetization along with high dc resistivity. The observed variations in saturation magnetization and crystallite size as a function of annealing temperature were elucidated considering the core surface magnetic interactions and the particle shape of the nanoferrite using low temperature in-field Mössbauer measurements and the high-resolution transmission electron micrographs. With the attainment of valuable magnetization and resistivity, the usefulness of the material as magnetic core for high frequency applications has been investigated by studying the frequency dependence of initial permeability. Interestingly, the results support that the material would be suitable as magnetic core up to 18 GHz.