Theoretical studies on the spin Hamiltonian parameters of Er3+ in ErxY1−xBa2Cu3O6

The spin Hamiltonian (SH) parameters anisotropic g factors g∥, g⊥ and the hyperfine structure constants A∥, A⊥ of Er3+ in ErxY1−xBa2Cu3O6 (x=0.6, 0.2 and 0.05) are theoretically studied from the perturbation formulas of these parameters for a 4f11 ion in tetragonal symmetry. In these formulas, the contributions to the SH parameters from the second-order perturbation terms and the admixtures of various excited states are taken into account. The related crystal-field parameters are determined from the superposition model. The theoretical results show reasonable agreement with the observed values.