Modulating Superconductivity with Metamaterial Plasmonic Structures - Experiment

In 1972, Kirzhnits et al. reformulated the BCS superconductivity theory in terms of a dielectric response function, concluding that the strength of Cooper pairing can be controlled by the dielectric environment. A demonstration of this effect was recently given in a metamaterial composite made of Al nanoparticles, designed to have suppressed dielectric function at the Eliashberg function maximum, leading to threefold increase of superconductivity critical temperature. We report fabrication and experimental measurements of thin film Babinet metamaterials made of Pb, designed to have the Cooper pairing strength systematically controlled (enhanced or suppressed). This work is coupled to a parallel effort to determine these effects theoretically.