Abstract:
The $g$ factors and the hyperfine structure constants of the Cr$^{4+}$ and Mn$^{5+}$ centers in silicon are theoretically investigated using the perturbation formulas of these parameters for 3$d^2$ ions in tetrahedra. In the calculations, both the contributions from the crystal-field and charge transfer mechanisms are taken into account based on the cluster approach. The calculated results show agreement with the observed values. It is found that the relative importance of the charge transfer contributions to the $g$-shift $\Delta_g=g-g_s$ (where $g_s$ = 2.0023 is the spin-only value) increases significantly with increasing the valence state of the impurity ion.