Investigations of the spin-Hamiltonian parameters and defect structures for Gd3+ ions in YMO4 (M=V, P, As) crystals

A 56×56 energy matrix containing the ground multiplet 8S7/2 and the excited multiplets 6L7/2 (where L=P, D, F, G, H, I) for 4f7 ion Gd3+ at a tetragonal crystal field and under an external magnetic field is constructed. By diagonalizing the energy matrix, the spin-Hamiltonian parameters (g factors g‖, g⊥ and zero-field splittings b20, b40, b44, b60, b64) for Gd3+ ion at the tetragonal Y3+ site of YMO4 (M=V, P, As) crystals are calculated. The calculated results are in reasonable agreement with the experimental values. The defect structures of Gd3+ centers in YMO4 crystals are estimated from the calculation. The results are discussed.