KNIGHT-SHIFTS AND NUCLEAR-SPIN-RELAXATION RATES FOR 2-DIMENSIONAL MODELS OF CUO2

Using spin-wave and random-phase-approximation expressions for the dynamic spin susceptibility of a two-dimensional CuO2 lattice, we have calculated the NMR Knight shifts K and spin-relaxation rates T1-1 at various nuclear sites for the insulating and metallic phases. Our results suggest that the observed differences in the NMR data taken on different sites are qualitatively consistent with a model that has strongly hybridized Cu(3d)-O(2p) orbitals. Within this picture, local antiferromagnetic correlations produced by on-site Coulomb interactions enhance the large-momentum part of the spin susceptibility. These correlations are then spatially filtered by the hyperfine form factors leading to different local-site behavior. © 1990 The American Physical Society.