Nanomaterials with tunable electronic structure exploit the large specific surface area of metal nanostructures along with the strategy of tuning the surface properties through the controlled introduction of space-charge regions for creating materials with tunable macroscopic properties. Photonic metamaterials provide an unconventional optical response in the extreme, negative refractive indices – by lithographically structured elements such as arrays of split-ring resonators (SRR). It is tempting to combine these two materials design strategies into a photonic metamaterial in which the space-charge at the surface of each SRR is controlled via an applied potential. Since the space charge couples into the electric resistivity, the resonance frequency of the metamaterials as well as the damping would be reversibly hifted. Our research indeed confirms that concept, exemplifying the new opportunities for designing functional nanomaterials which exploit nanoscale structure along with interfacial processes at electrode surfaces.

This work is performed in close cooperation with the Institut für Angewandte Physik at Karlsruhe Institute of Technology (KIT). Funding by the Center for Functional Nanostructures at KIT is acknowledged.