Unified research of the EPR and optical spectral data for Cr3+-doped Lu3Al5O12 crystal

In this article, we apply a complete diagonalization (of energy matrix) method to simultaneously calculate the spin-Hamiltonian (or EPR) parameters (g factors g//, g⊥ and zero-field splitting D) and optical band positions (or crystal field energy levels) of Cr3+-doped Lu3Al5O12 (LuAG) crystal. The method is based on the two-spin-orbit-parameter model where besides the effects of spin-orbit parameter of central dn ion in the common crystal-field theory, those of ligand ions are contained. The calculated results indicate that by using only three adjustable parameters, the eight observed spectroscopic data (three EPR data and five optical bands) are reasonably explained. This suggests that this diagonalization method is effective and applicable in the unified calculation of EPR and optical spectral data for d3 ions in crystals. The local lattice distortion caused by the Cr3+ impurity in LuAG crystal is also estimated. The outcomes are discussed.