Spin-lattice coupling of Mn²⁺ions in calcite

Abstract

It is found theoretically that the spin-lattice coupling constant GA1 is proportional to the axial zero-field splitting parameter D for a 6S-state ion in D3d symmetry. A study of the ratio GA/sup //1D provides an effective way of deciding the relative importance of the various mechanisms which contribute to the zero-field splitting. For Mn2+ in calcite (CaCO3) the spin-orbit coupling mechanism accounts for the parameters D, GA1 and GA2 and the ratio GA1/D very well; either the point-charge model or the superposition model of a crystal field is adopted. In contrast, no other mechanism fits the ratio. This indicates that the spin-orbit coupling mechanism is the most important. In addition, the superposition model of the spin Hamiltonian is found to interpret the parameters D, GA1 and GA2 very well.