Optically isotropic negative permeability in the visible range and optically isotropic negative refraction index in the interband range

So-called magnetic nanoclusters -- the raspberry nanostructure composed by a spherical metamaterial shell of a submicron dielectric core. The metashell is formed by mutually touching plasmonic nanospheres adsorbed on the common core of diameter 35-70 nm. Nanospheres of diameter 20-40 nm are ohmically isolated from one another by a 2-3 nm thick dielectric covering or by an encapsulation.

Core-shell metal-semiconductor nanoparticles with metal core and Si or Ge shell. This work was targeted to the creation of a novel class of optical metamaterials (with isotropic artificial magnetism and with isotropic negative refractive index in the visible and near infrared). It was supported by the FP7 METACHEM project.