Abstract:

It has been customary to compute the effect of spin-orbit coupling on the magnetic properties of transition metal ions in crystals with the expression taken over from atomic spectroscopy, although this expression is valid only in a spherically symmetric field. In the present work, we show how the use of a spin-orbit interaction Hamiltonian derived from the Bethe-Salpeter approximation to the relativistic Breit equation for a partly covalent complex leads to a dependence of the gyromagnetic factor on the spin-orbit coupling parameter of the ligand atoms. We develop an expression of g for a d8-ion in a cubic field and apply it to the case of KNiF3. The calculated g values agree very well with experimental results. Other differences between our expression and those found by other authors are discussed.