Resonance variations of microwave reflection coefficient in nanocomposite sample with cobalt and palladium particles

Abstract The influence of microwave resonance phenomena on the transmission and reflection coefficients in a nanocomposite sample based on the opal matrix with embedded cobalt and palladium particles at frequencies from 26 to 38 GHz has been experimentally studied. With changing magnetic field, strong resonant-type variations in the transmission and reflection coefficients have been revealed. These variations have been found to be caused by both high efficiency of interaction of the millimetre-range electromagnetic waves with the nanocomposite, in particular, under the ferromagnetic resonance condition, and fulfilment of the geometric resonance conditions. At that, the geometric resonances are caused by the interference of waves that propagate in the plate towards each other and arise when an integer number of half wavelengths fit within the plate thickness. It has been shown that the half-wave geometric resonance can lead to a large, up to 100%, increase in the reflection coefficient of microwaves under the fulfilment of the ferromagnetic antiresonance condition.