Uniform explanation of the optical and electron paramagnetic resonance spectral data for La3Lu2Ga3O12: Cr3+ crystal

The optical and electron paramagnetic resonance (EPR) spectral data for Cr3+ ion in trigonal Lu3+ octahedral site of La3Lu2Ga3O12 (LLGG) crystal are computed in union from the complete diagonalization (of energy matrix) method based on the two-spin-orbit-parameter model. The model takes account of not only the contributions from the spin-orbit parameter of central dn ion in the conventional crystal-field theory, but also those of ligand ion via covalence effect. From the calculations, the observed three crystal-field energy levels (or optical bands) and three spin-Hamiltonian parameters (g factors g//, g⊥ and zero-field splitting D) are rationally explained in a unified way. The large angular distortion of Cr3+ impurity center in LLGG: Cr3+ crystal due to the great size mismatch is also acquired. The results are discussed.