Magnetic resonance and antiresonance in 3D nanocomposites based on opal matrices

In recent years, the infrared and microwave properties of opal matrices have been intensively studied [1]. It is thought that the opal matrices containing nanoparticles of magnetic materials in the intersphere voids may form a most promising class of materials used in centimeter- and millimeter-wave devices [2, 3]. Nickel-zinc, cobalt-zinc, and other ferrites seem to be proper materials for the filling owing to a lucky combination of such properties as high resistivity, low dielectric loss, high Curie temperature, and chemical stability. Application of microwave methods seems to be effective since these methods enables to estimate the dynamical and relaxation parameters of materials. Microwave properties of opal matrices containing the nanoparticles of different ferrite-spinels in the inter-sphere voids are discussed in this work. Microwave properties are measured at frequencies of millimeter waveband. Variations of a microwave signal passed through the magnetic nanocomposite occur mainly due to variations of the surface impedance under magnetic resonance condition and due to absorption of the wave. At higher frequencies the antiresonance is possible in fields lower than the resonance field. The antiresonance manifests itself as a maximum of transmission and/or reflection coefficients.