Magnetic permeability, losses and ferromagnetic resonance in ferrites under magnetic field bias from DC to the microwave regime

Fluxmetric and transmission line methods have been combined to achieve accurate determination of energy loss and complex permeability in soft ferrites from DC to microwave frequencies. Superposition of the results in the MHz frequency range proves instrumental to obtain reproducible data and traceability to the appropriate standards. Permeability curves are strongly affected by ferromagnetic resonance, which can be frequency shifted using a bias field applied transverse to the AC exciting field. The permeability behavior can be correctly predicted by physical modeling, allowing one to separate domain wall and rotational processes, respectively associated with pure relaxation effects and bias field dependent damped resonant behavior.