Spin-spin and spin-other-orbit effects of optical spectra and the spin-Hamiltonian parameters for Cr3+ ions in MgO crystals

An extended complete diagonalization method/microscopic spin-Hamiltonian (CDM/MSH) program has been developed, which is applicable for d3 ions at sites of tetragonal symmetry type I (C4v, D2d, D4, D4h) and trigonal symmetry type I (C3v, D3, D3d). The Hamiltonian includes the spin-spin (SS) and spin-other-orbit (SOO) magnetic interactions besides the spin-orbit (SO) magnetic interaction usually taken into account. Utilizing the extended CDM/MSH program, the optical spectra, the spin-Hamiltonian (SH) parameters of the ground state 4B1, and the splitting δ(2E) of the first excited 2E state for Cr3+ (3d3) ions at C4v symmetry sites in MgO crystals have been successfully investigated. It is found that although the SO magnetic interaction is the most important one, the contributions to the SH parameters and the optical spectra from the SS and SOO magnetic interactions for Cr3+:MgO crystals are appreciable and should not be omitted, especially reaching 27.8% for the zero field splitting parameter D.