Heterogeneity of microwave electromagnetic field inside of artificial magnetic crystal

Abstract The nanocomposite artificial crystals with embedded magnetic nanoparticles are obtained from opal matrices composed of the submicron SiO2 spheres. The introduced particles are sized from 5 to 60 nm. These artificial crystals contain metallic cobalt, nickel and iron particles, nickel-zinc ferrite and silver particles. The complex refractive coefficients at frequencies of centimeter and millimeter waveband are obtained as a function of magnetic field. A parameter, characterizing the heterogeneity of electromagnetic fields at different distances from a magnetic particle, has been calculated. The complex refraction coefficient can be expressed via the effective dielectric permittivity and magnetic permeability. Analysis of the space distribution of the heterogeneity parameter for the artificial crystal with metallic cobalt particles at 14 GHz in external magnetic field shows that very strong variations of the nonuniformity parameter are observed near ferromagnetic resonance (FMR), and much smaller variations for the fields exceeding FMR. In all cases the averaging over the distance in 2 – 3 times exceeding the lattice parameter of the artificial opal crystal leads to damping of strong oscillations.