Negative index materials based on metal nanoclusters

We present a negative index metamaterial architecture based on metal nanoclusters. The nanoclusters support magnetic Mie resonances and exhibit negative permeability, which can be combined with negative permittivity to achieve negative refractive index. We demonstrate two designs using silver nanoclusters with either silver films or silver coated nanowires in optical frequency region. Refractive index of −1 and figure of merit of 2 are achieved by sandwiching nanoclusters between silver films. Our simulations show the flexibility in constructing negative index materials using metal nanoclusters due to their tunable operating frequencies and the freedom in the choice of the material compositions.