Investigations of the spin-Hamiltonian parameters and tetragonal compression due to the static Jahn-Teller effect for Cr5+ center in cubic SrTiO3 crystal

By using the distortion model that the tetragonal site symmetry of Cr5+ in cubic phase of SrTiO3 originates from the static Jahn-Teller effect, the spin-Hamiltonian parameters (g factors g||, g⊥ and hyperfine structure constants A||, A⊥) of this tetragonally compressed Cr5+ center in SrTiO3 are calculated from the high-order perturbation formulas based on a two-mechanism model. In the model, not only the contribution to spin-Hamiltonian parameters due to the crystal-field mechanism, but also that due to the charge-transfer mechanism (which is omitted in the extensively used crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. The tetragonal compression (characterized by ΔR=R⊥−R||, where R⊥ and R|| denote the metal-ligand distances perpendicular to and parallel with the C4 axis) of Cr5+ center is also obtained from the calculation. The results (including the tetragonal compression and the relative importance of the charge-transfer mechanism) are discussed.