Mott insulator to high T_c superconductor via pressure: resonating valence bond theory and prediction of new systems

Abstract

Mott insulator superconductor transition, via pressure and no external doping, is studied in orbitally nondegenerate spin-½ systems. It is presented as another resonating valence bond route to high T_c superconductivity. We propose a "strong coupling"hypothesis that views long range Coulomb force driven first order Mott transition as a self-doping process that also preserves superexchange on the metal side. We present a two-species t-J model where conserved N0 doubly occupied (e^-) sites and N₀ empty sites (e+) hop in the background of N-2N₀ singly occupied (neutral) sites in a lattice of N sites. An equivalence to the regular t-J model is made. Some old and new systems are predicted to be candidates for pressure-induced high T_c superconductivity.