Possibilities for enhanced electron-phonon interactions and high-T_c superconductivity in engineered bimetallic nanostructured superlattices

We theoretically investigate the properties of engineered bimetallic nanostructured superlattices, wherein arrays of nanoclusters composed of a simple (single-band) metal are periodically embedded within another simple metal that possesses a different work function. This analysis is conducted using a simplified tight-binding model incorporating Coulomb interactions, alongside density functional theory calculations. As a representative case, we consider arrays of fixed-sized, unrelaxed "Ag" clusters periodically embedded within an "Au" matrix. Our findings reveal a significant enhancement of electron-phonon interactions, suggesting potential for high-temperature superconductivity. This enhancement arises from a robust coupling, mediated by Coulomb interactions, between the dipolar charge distribution at the Au-Ag interfaces and the vibrational modes, such as breathing modes, of the lighter Ag atoms within the heavier Au matrix. These interfacial dipoles result from the mismatch between the local potentials experienced by conduction electrons in Wannier orbitals at the Ag and Au sites (with Ag sites being slightly repulsive compared to Au), coupled with long-range Coulomb repulsion between electrons in these orbitals. We also provide insights into DC transport properties in these systems.