Nonbonding oxygen holes and spinless scenario of magnetic response in doped cuprates

Both theoretical considerations and experimental data point to a more complicated nature of the valence hole states in doped cuprates than it is predicted by Zhang – Rice model. Actually, we deal with a competition of conventional hybrid Cu $3d$-O $2p$ $b_{1g}\propto d_{x^2 -y^2}$ state and purely oxygen nonbonding state with $e_{u}x,y \propto p_{x,y}$ symmetry. The latter reveals a non-quenched Ising-like orbital moment that gives rise to a novel spinless purely oxygen scenario of the magnetic response in doped cuprates with the oxygen localized orbital magnetic moments of the order of tenths of Bohr magneton. We consider the mechanism of ${}^{63,65}$Cu-O $2p$ transferred orbital hyperfine interactions due to the mixing of the oxygen O $2p$ orbitals with Cu $3p$ semicore orbitals. Quantitative estimates point to a large magnitude of the respective contributions both to local field and electric field gradient, and their correlated character.