材料期刊网

The spin Hamiltonian parameters (the anisotropic g factors g(parallel to) and g(perpendicular to) and the hyperfine structure constants) for the Cu(2+) sites in PrBa(2)Cu(3)O(6+x) and Pr(0.5)Er(0.5)Ba(2)Cu(3)O(6+x) are theoretically investigated using the high order perturbation formulas of these parameters for a 3d(9) ion in tetragonally elongated octahedra. In these formulas, the tetragonal field parameters are determined from the superposition model and the local structures of the Cu(2+) The theoretical spin Hamiltonian parameters are ill good agreement with the observed values for both systems, and the results show improvements as compared with those based on various adjustable covalency coefficients in the previous work. The larger hyperfine structure constants for PrBa(2)Cu(3)O(6+x) than those for Pr(0.5)Er(0.5)Ba(2)Cu(3)O(6+x) can be attributed to the weaker covalency clue to the relatively longer Cu(2+)-O(2) bonds in the former.