Estimation of the On-Site Coulomb Potential and Covalent State in La2CuO4 by Muon Spin Rotation and Density Functional Theory Calculations

The on-site Coulomb potential, U, and the covalent state of electronic orbitals play key roles for the Cooper pair symmetry and exotic electromagnetic properties of high-T-c superconducting cuprates. In this paper, we demonstrate a way to determine the value of U and present the whole picture of the covalent state of Cu spins in the mother system of the La-based high-T-c superconducting cuprate, La2CuO4, by combining the muon spin rotation (mu SR) and the density functional theory (DFT) calculation. We reveal local deformations of the CuO6 octahedron followed by changes in Cu-spin distributions caused by the injected muon. Adjusting the DFT and mu SR results, U and the minimum charge-transfer energy between the upper Hubbard band and the O 2p band were optimized to be 4.87(4) and 1.24(1) eV, respectively.