Analysis of the Electric Field Gradients and the Knight Shifts at All Cu and O Nuclei in YBa₂Cu₃O₇

抄録

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_σ holes for O sites, it is necessary to consider 4p electrons of Cu and 2p_π 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).