材料期刊网

The EPR g factors for the tetragonal NdBa2CU3O7-delta high-T-c superconductor are theoretically investigated on the basis of the perturbation formulae of the g factors for a 4f(3) ion in tetragonal symmetry. The contributions to the g factors arising from the second-order perturbation terms, the admixture of various states and the covalency effect are included in these formulae. The relevant crystal-field parameters are determined from the superposition model and the local structural data of the tetragonal Nd3+ site in NdBa2CU3O7-delta. The calculated g factors are in reasonable agreement with the observed values. The validity of the results is discussed.