Structure, morphology and magnetic performance of (Fe₆₅Co₃₅)_x@(Ni_0.5Zn_0.5Fe₂O₄)_100–x nanocomposite thin films

Abstract A bi-magnetic phase (Fe 65 Co 35 ) x @(Ni 0.5 Zn 0.5 Fe 2 O 4 ) 100–x nanocomposite thin film was created by combining Fe 65 Co 35 alloy nanoclusters produced through plasma gas condensation with Ni 0.5 Zn 0.5 Fe 2 O 4 thin film prepared via RF magnetron sputtering. The study revealed that the Fe 65 Co 35 alloy nanoclusters, with an average particle size of approximately 6 nm, are surrounded by the amorphous ferrite phase, forming a granular ‘core–shell’ structure. As the proportion of Fe 65 Co 35 alloy nanoclusters increased from 5.9 wt% to 35.4 wt%, the grain size of the nanocomposite thin films decreased from 24 nm to 10.4 nm. Magnetic analysis demonstrated that the nanocomposite thin films displayed soft magnetic properties at room temperature. With an increase in Fe 65 Co 35 content, the saturated magnetization of the nanocomposite thin films escalated from 68 emu cm −3 to 214 emu/cm 3 , significantly surpassing that of the corresponding NiZn ferrite films (∼17 emu/cm 3 ). The fluctuation of coercivity is intricately linked to the grain size of the nanocomposite thin films, and at 24.5 wt% of Fe 65 Co 35 alloy nanoclusters, the coercivity is minimized to 14 Oe. The ferromagnetic resonance spectra of the nanocomposite films exhibited some asymmetric broadening and shift. As the Fe 65 Co 35 content increased, the resonance field initially decreased and then rose, while the resonance linewidth gradually decreased.