The electric hyperfine interaction observable in atomic spectroscopy for O and Cu ions in various configurations is used to analyze the quadrupole splitting of O and Cu nuclear magnetic resonance (NMR) in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$ and ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+y}$ and to determine the hole densities at both sites as a function of doping. It is found that in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$ all doped holes (x) reside in the Cu-O plane, but almost exclusively at O. For ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+y}$ and $y<\mathrm{}0.6\mathrm{}$ doped holes are found at planar Cu as well as O. For $y>\mathrm{}0.6\mathrm{}$ further doping increases the hole content only for planar O. The phase diagram based on NMR data is presented. Further implications from the Cu A and B sites in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$ and the two planar O sites in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+y}$ and consequences for the phase diagram are discussed.

• Received 3 July 2003

DOI:https://doi.org/10.1103/PhysRevB.69.094504