Ferromagnetic Resonance in Nanocomposite Metal-Dielectric Films with Different Types of the Structure

Based on the theory of magnetic dynamics and in the mean field approximation, expressions for the position and linewidth of the ferromagnetic resonance (FMR) line have been obtained, the values of which were determined through the average demagnetizing coefficient of metallic granules in composite films. The demagnetization coefficient was determined experimentally through the porosity of the composite film. The obtained theoretical concentration dependencies of the position and linewidth of the FMR line were compared with experimental dependencies for two series of composite films with different metallic alloys: (CoFeB+MgO), (CoTaNb+MgO). The observed maximum linewidths of the FMR line in the films are related to the formation of a percolation structure in the films. The developed theoretical model in this work takes into account the different distribution and topology of granules in metal-dielectric composite films through the demagnetizing coefficient. This model explains the differences in amplitudes and positions of the maxima for the two series of films observed in the presence of a percolation structure.