Investigation of FeCo-Ti-O nanogranular films with tunable permeability spectrum

A series of soft magnetic nanogranular FeCo-Ti-O films with different Ti contents were fabricated on Si substrates by co-sputtering. By adjusting the Ti content, it appears that the imaginary part of the permeability spectra of FeCo-Ti-O films changes from a single peak to double peaks then to a single peak. Frequency conversion ferromagnetic resonance (FMR) analysis evidences that double FMR peaks can be found in all three films, which were attributed to local anisotropy or two magnetic phases embedded in amorphous TiOx matrix. Structural and temperature dependent resistivity analysis support such three component microstructure. The overlapping double FMR peaks provide a wide absorption frequency band over 3 GHz, which is critical for the design of electromagnetic interference suppressor.