Optical metamaterials with different metals
  We investigate the influence of different metals on the electromagnetic response of fishnet metamaterials in the optical regime.We found, instead of using a Drude model, metals with a dielectric function from experimentally measured data should be applied to correctly predict the behavior of optical metamaterials. Through comparison of the performance for fishnet metamaterials made with different metals (i.e., gold, copper, and silver), we found silver is the best choice for the metallic parts compared to other metals, because silver allows for the strongest negative-permeability resonance and, hence, for optical fishnet metamaterials with a high figure-of-merit. Our study offers a valuable reference in the designs for optical metamaterials with optimized properties. 
Nian-Hai Shen, Thomas Koschny, Maria Kafesaki, and Costas M. Soukoulis
physics.optics