Fate of doped carriers in silver fluoride cuprate analogs

Abstract

${\mathrm{AgF}}_{2}$ is a correlated charge-transfer insulator with properties remarkably similar to insulating cuprates, which have raised hope that it may lead to a new family of unconventional superconductors upon doping. We use ab initio computations to study doping strategies leading to metallization. Because the upper Hubbard band is very narrow electron doping leads to undesired strongly self-trapped states (polarons). For the hole-doped case, the polaron tendency is stronger than for cuprates but still moderate enough to expect that heavily doped compounds may become metallic. Since the strong electron lattice coupling originates in the strong buckling we study also an hypothetically flat allotrope and show that it has excellent prospect to become metallic. We compare the ${\mathrm{AgF}}_{2}$ behavior with that for the hole-doped conventional cuprate ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ and electron-doped ${\mathrm{Nd}}_{2}{\mathrm{CuO}}_{4}$. Our results show a clear path to achieve high-temperature superconductivity in silver fluorides.