Magnetooptics of opal crystals modified by cobalt nanoparticles

Abstract

Optical and magnetooptical properties of opal photonic crystals modified by Co nanoparticles have been investigated by modulation spectroscopy technique in the visible spectral range from 400 to 800 nm. The Co nanoparticles of 1 to 8 nm in size were formed by means of chemical reduction reaction inside synthetic opal crystals composed of regularly close-packed SiO2 spheres of diameter 250–300 nm. As it was estimated from the spectral shift of the stop band of photonic crystals, Co nanoparticles occupied up to several percent of void volume in opal crystal lattice. In the Faraday configuration, external magnetic field induced the change in optical transmission normalized to sample thickness 1 cm and magnetic field 1 T equal to 0.10–0.35 for Co-modified opal crystals in the spectral range under consideration. The fabricated hybrid structures can be considered as a possible prototype of magnetophotonic crystals. Keywords: magnetophotonic crystals, modulation spectroscopy