Theoretical investigations on the spin Hamiltonian parameters and local structures for the trigonal Ni2+ centers in CsMgX3 (X=Cl, Br, I)

Abstract

The spin Hamiltonian parameters (zero-field splitting and the anisotropic g factors) and the local structures for the trigonal Ni2+ centers in CsMgX3 (X=Cl, Br, I) are theoretically investigated from the perturbation formulas of these parameters for a 3d8 ion in trigonally distorted octahedra, by including the ligand s-orbital contributions. Based on the studies, the local impurity-ligand bond angles β related to the C 3 axis in the Ni2+ centers are found to be about 2° larger than the corresponding angles, βH, in the hosts, due to the size mismatching substitution of Mg2+ by Ni2+. The theoretical results based on the inclusion of the ligand s-orbital contributions show an improvement when compared with those in the absence of the above contributions, especially for the ligand I−.