Microwave properties of granular amorphous carbon films with cobalt nanoparticles

Abstract

We have studied losses of microwave electromagnetic radiation in granular amorphous hydrogenated carbon films a-C:H(Co) containing cobalt nanoparticles at cobalt concentrations below the percolation threshold and in the percolation threshold region. The difference between the experimental values of the losses in granular structures sputtered on corundum-based substrates and those on aramide tissues is observed. It is found that this is determined by the difference in localization sizes of cluster electron states in a-C:H(Co) films. We have found that losses grow with increasing concentration of cobalt nanoparticles and with increasing frequency. The frequency dependence of losses is determined by the fast spin relaxation of nanoparticles. The anisotropy of losses in a-C:H(Co) covers on aramide tissues is observed.