Theory of Confined High Tc Superconductivity in Monovalent Metals
Abstract
Monovalent non-transition metals are robust Fermi liquids. They defy superconductivity even at lowest temperatures (Li is a minor exception:Tc ≈ 0.4 mK). However, Thapa and Pandey ThapaPandey have recently reported signals for ambient temperature granular superconductivity in Ag nanoparticle embedded in Au matrix. We develop a theory, where competing superconducing, CDW and SDW orders lose and get confined (go off-shell). They leave behind a robust Fermi liquid on-shell. A single half filled band crossing the Fermi level provides a number of special k-space regions for singlet stabilizing umklapp pair scattering and superconductivity stabilizing repulsive pair scattering. Carefully designed perturbations could deconfine a confined superconductivity. We suggest that electron transfer (doping) from Ag nanoparticles to Au matrix (with a higher electronegativity), quasi 2d structural reconstructions (e.g., 9R structure) at Ag-Au interfaces etc., bring out confined superconductivity. Beneath a calm Fermi sea, strong supercurrents may exist in several metals.