Broad Band Mott Localization is all you need for Hot Superconductivity: Atom Mott Insulator Theory for Cu-Pb Apatite

Abstract

A hypothetical non-dimerized Cu chain in equilibrium is a spin-\half atom Mott insulator (AMI), eventhough its band width is high ~ 10 eV. This RVB reservoir has a large exchange coupling J ~ 2 eV. This idea of, \textit{broad band Mott localization} was used by us in our earlier works, including prediction of high Tc superconductivity in doped graphene, silicene and a theory for hot superconductivity reported in Ag-Au nanostructures (TP 2008). In the present work we identify possible random AMI subsystems in Cu-Pb Apatite and develop a model for reported hot superconductivity (LKK 2023). In apatite structure, network of interstitial columnar spaces run parallel to c-axis and ab-plane. They accomodate excess copper, as neutral Cu atom clusters, chains and planar segments. They are our emergent AMI's. Electron transfer from AMI's to insulating host, generates strong local superconducting correlation, via phyics of doped Mott insulator. Josephson coupling between doped AMI's, establishes hot superconductivity. A major Challenge to superconducting order in real material is competing insulating phases - valence bond solid (spin-Peirels)-lattice distortions etc. AMI theory points to ways of making the \textit{elusive superconductivity} palpable. We recommend exploration of hot superconductivity in the rich world of minerals and insulators, via metal atom inclusion.