Circular Dichroism in Chiral Metamaterials Based on Nanostructured Cobalt Films

The results of experimental studies of chiral film structures based on arrays of cobalt nanohelixes obtained by oblique angle deposition on a transparent substrate are presented. Under electron-beam evaporation conditions, an array of nanohelixes twisted in one direction is formed on a rotating tilted substrate. By varying the substrate rotation speed, the geometric dimensions of the nanohelixes (helix pitch, helix radius) can be altered. The chiral thin-film metamaterials obtained in this manner have been shown to exhibit pronounced circular dichroism, which can be used to create photonic elements, including those controlled by magnetic fields.