ANALYSIS OF THE ELECTRIC-FIELD GRADIENTS AND THE KNIGHT-SHIFTS AT ALL CU AND O-NUCLEI IN YBA2CU3O7

Electronic configurations and local susceptibilities at all copper and oxygen sites in YBa2Cu3O7 are determined from the analysis of the electric field gradients (EFG's) and the Knight shifts (shifts). Besides main contributions from 3d holes for Cu sites and 2p(sigma) holes for O sites, it is necessary to consider 4p electrons of Cu and 2p(pi) holes of O for accurate analysis of the EFG's, and 4s electrons of Cu and 2s holes of O for the shifts. Difference in the observed EFG's between Cu(1) and Cu(2) is due to the 4p-electron contributions, and the 3d-electron states are determined to be quite similar. Each site of Cu and O shares almost same amount of holes. The local spin susceptibilities, however, are fairly different in order of magnitude as Cu(2), Cu(1), O(2, 3), O(4), implying a strong correlation in Cu(2).