Electron spin resonance properties of semiconductor/granular film heterostructures with cobalt nanoparticles in millimeter waveband

Ferromagnetic resonance spectra (FMR) on heterostructures of amorphous silicon dioxide films containing cobalt nanoparticles, (SiO2)100−xCox, grown on GaAs and Si substrates have been investigated over a frequency range of 37–41 GHz at room temperature. The FMR linewidth and saturation magnetization dependencies on the cobalt concentration have been analyzed. The impact of the semiconductor type on the FMR linewidth ΔH and a sharp increase in ΔH with a decreasing concentration of cobalt nanoparticles have been noted. The effect of considerable FMR linewidth broadening has been accounted for by the spin-polarized relaxation mechanism.