Observation of plasmon-phonons in a metamaterial superconductor using inelastic neutron scattering (Conference Presentation)

A metamaterial approach is capable of drastically increasing the critical temperature, ${T}_{\mathrm{c}}$, of composite metal-dielectric superconductors as demonstrated by the tripling of ${T}_{c}$ that was observed in bulk Al-${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ core-shell metamaterials. A theoretical model based on the Maxwell-Garnett approximation provides a microscopic explanation of this effect in terms of electron-electron pairing mediated by a hybrid plasmon-phonon excitation. We report an observation of this excitation in Al-${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ core-shell metamaterials using inelastic neutron scattering. This result provides support for this mechanism of superconductivity in metamaterials.