Resonance frequency above 20 GHz in superparamagnetic NiZn-ferrite

We investigate the frequency dispersion of complex permeability in GHz range superparamagnetic nickel–zinc ferrite thin films with different Ni/Zn ratios using a microstrip probe. The films, comprising crystallites as small 3 nm and deposited by microwave-irradiation-assisted solvothermal method, exhibit coexistence two resonance characteristics—a ferromagnetic peak ([Formula: see text]) at ∼2 above 20 GHz, breaching Snoek's limit. high value [Formula: text] is attributed to surface anisotropy far-from-equilibrium distribution cations lattice, while thermally driven relaxation nanocrystallites films. This work demonstrates feasibility employing so excellent CMOS-integrable magnetic components for high-speed high-frequency electromagnetic device applications.