Enhancing superconductivity with resonant anti-shielding and topological plasmon-polarons

Abstract

By employing ab initio Migdal-Eliashberg calculations, we predict a 4-fold enhancement of the superconducting critical temperature of MgB$_{2}$ when proximity-coupled to the topological crystal Bi$_{2}$Se$_{3}$. We support this result with calculations using the general Leavens scaling method. We show that this effect is a result of dynamic resonant anti-shielding of Cooper pairs by plasmon polarons of Dirac electrons in the topological crystal. Our calculations show that such superconductivity enhancement varies strongly with Coulomb coupling between plasmon polarons and Cooper pairs, with a pronounced maximum of $\textit{T}_{c}$ at a critical value of the coupling parameter. This feature is universal, and so can occur in other superconductor-topological crystal combinations, including with non-phonon mediated superconductors. We discuss methods to experimentally optimize the key coupling parameter.