Theoretical studies bask solid state physics of the spin Hamiltonian parameters for the tetragonal Co4+ and Ir4+ centers in SrTio(3)

The spin Hamiltonian parameters, g factors and the hyperfine structure constants for Co4+ (3d(5)) and Ir4+ (5d(5)) in SrTiO3 are theoretically studied from the formulas of these parameters for an nd(5) (n = 3 and 5) ion in a tetragonally distorted octahedron with low spin S = 1/2. According to the theoretical analyses, the impurity-ligand bond lengths R-parallel to' parallel to the C-4 axis are found to be larger than the host values R-parallel to based on the phase transition rotation angles phi of the [TiO6](8-) octahedron by the C-4 axis at 4.2 and 77 K, respectively. The elongation of the ligand octahedra in the host may be enhanced in the impurity centers by the Jahn-Teller effect of the nd(5) ions. The theoretical results based on the above local structures show good agreement with the experimental data.