材料期刊网

High-order perturbation formulas for the electron paramagnetic resonance g factor for a 3d(7) ion in cubic tetrahedral MX4 clusters are established from a cluster approach. In the formulas, not only the conventional contribution from the crystal-field (CF) mechanism, but also the contribution from charge-transfer (CT) (which is often omitted) are considered. Based on the formulas, the g-shifts Deltag (=g-g(s), where g(s)=2.0023) of Co2+ ions in III-V semiconductors GaP, InP, and GaAs are reasonably explained. It is found that the relative importance of the CT mechanism (characterized by Deltag(CT)/Deltag(CF)) increases with increasing covalency and hence with increasing atomic number of the ligand. Therefore, for 3d(n) ions in a strongly covalent crystal, the contributions to the g factor from both CF and CT mechanisms should be taken into account. (C) 2004 American Institute of Physics.