An interpretation of the g factors for the tetragonally-compressed Cr ~5 centers in YVO _4 and YPO _4 crystals

摘要

The g factors g ∥ and g ⊥ for the tetragonally-compressed (CrO _4) ~(3-) clusters in YMO _4 (M=V, P) crystals are calculated from the high-order perturbation formulas based on the two-mechanism model for the compressed d ~1 tetrahedra with the ground state |dz ~2〉. From the calculated values and by considering a small admixture of the first excited state |dx ~2-y ~2〉 to the ground state |dz ~2〉 due to the vibrational motion of ligands (which leads a twinkling compressed tetrahedron to become an elongated one), the observed g ∥ and g ⊥ for Cr ~5 centers in YMO _4 crystals are explained reasonably. The difficulty of the large deviations of g ∥ from g _e (≈2.0023) in the two systems is therefore removed and the above dynamic effect may be the cause which results in the large deviation of g ∥ from g _e for some (CrO _4) ~(3-) clusters in crystals.