Correlated electronic structure of Pb10-xCux(PO4)6O

Recently, above-room-temperature superconductivity was reported in the Cu-doped lead apatite Pb10-xCux(PO4)6O, dubbed LK-99. By relaxing the structure with Cu substitution, we derive a four-band low -energy model with two 3/4 filled bands of predominantly Cu-dxz,yz character and two filled O-px,y bands. This model is further downfolded to a two-band Cu-dxz/yzmodel. Using ab initio derived interaction parameters, we perform dynamical mean-field theory calculations to determine the correlated electronic structure in the normal state. These calculations yield a Mott insulator at x = 1 and a strongly correlated non-Fermi-liquid metal upon doping. The very large interaction versus bandwidth ratio U/W approximate to 30-50 and the local moment paramagnetic behavior in the relevant filling regime are hard to reconcile with diamagnetism and high-temperature superconductivity. Our calculations suggest that this behavior comes from a component with a different stoichiometry.