Theoretical studies of the g factors and local structure for the tetragonal Nd3+ center in SrTiO3.

The anisotropic g factors g(//) and g(perpendicular) and the local structure for the tetragonal Nd(3+) center in SrTiO(3) are theoretically studied using the perturbation formulas of the g factors for a 4f(3) ion in tetragonal symmetry. This center is attributed to the impurity Nd(3+) occupying the dodecahedral Sr(2+) site in SrTiO(3), associated with one nearest neighbour interstitial oxygen O(I) along [001] (or C(4)) axis. The impurity Nd(3+) is found to suffer the large displacement (approximately 1.1A) towards the O(I) along the C(4) axis due to their strong interaction. The calculated g factors based on the above impurity axial displacement show reasonable agreement with the experimental results.