Model of isotropic resonant magnetism in the visible range based on core-shell clusters

The idea of isotropic resonant magnetism in the visible range of frequencies known from precedent publications was developed having in mind achievements of modern chemistry. Plasmonic colloidal nanoparticles covering a silica core form a cluster with resonant and isotropic magnetic responses. Two approximate models giving a good mutual agreement were used to evaluate the magnetic polarizability of the cluster and the permeability of the magnetic composite medium. The possibility of obtaining isotropic doubly-negative media in this way was also studied and the corresponding design was proposed.