Broadband Permeability Extraction of Soft Magnetically Tunable Fe–Co Nanoparticles

Radio frequency (RF) extraction of soft magnetic iron-cobalt (Fe-Co) nanoparticles is reported with high magnetization moment and low coercivity characteristics. Composite substrate containing magnetic Fe-Co nanoparticles and FR4 dielectric is presented. A broadband transmission line (TL) model has been developed to extract the permeability properties of 30-nm cubic nanoparticles. Broadband extraction procedure of the effective permeability is based on a combination of both: analytical perturbation and numerical curve fitting techniques using electromagnetic (EM) field simulator. The initial estimation of the EM properties is based on the perturbation theory for both baseline FR4 and composite substrates. Further optimization of the extracted values of permeability is performed by curve fitting the finite-element method simulated to measured scattering (S)-parameters for the composite TL.