Linear Electric Field Effect in Paramagnetic Resonance for CdS:Mn2+

We have measured the electric field shifts for ${\mathrm{Mn}}^{2+}$ in the wurtzite form of CdS. The three coefficients appearing in the linear-electric-effect Hamiltonian ${\mathcal{H}}_E=E_i{R}_{\mathrm{ijk}}{S}_j{S}_k$ are as follows: $R_{111}=\pm 40$, $R_{113}=1.2\mathrm{}$, $R_{311}=-7.5\mathrm{}$, where the units are MHz per ${10}^6$V/cm applied field. Theoretical calculations aimed at interpreting these results consist of two steps. The crystal field potentials $a_k^q{C}_k^q$ induced when the laboratory field is applied to the sample are calculated first; then these induced fields are used in conjunction with the normal crystal field potentials $A_K^Q{C}_K^Q$ to find the appropriate linear-electric-effect terms in the ${\mathrm{Mn}}^{2+}$ spin Hamiltonian. A pointdipole model has been used to calculate the $a_k^q{C}_k^q$ up to the fourth degree. The even $a_k^q{C}_k^q$ can be used in conjunction with the even $A_K^Q{C}_K^Q$ to derive the electric shifts. The odd $a_k^q{C}_k^q$ are first combined with odd $A_K^Q{C}_K^Q$ to give equivalent even-field potentials $a_k^q\mathrm{}\left(E\right)\mathrm{}{C}_k^q$, and these are then treated in the same way as the even $a_k^q{C}_k^q$. Three mechanisms have been considered in relating the crystal fields to the electric effects, and the experimental $R_{\mathrm{ijk}}$ have been fitted with three parameters representing the relative importance of each mechanism. The resulting fit has been tested by using it to predict the $D$ value. From this it appears that in CdS: ${\mathrm{Mn}}^{2+}$ the largest contribution arises from the second-degree induced potentials acting in conjunction with the second-degree potentials in the normal crystal field. Calculations also suggest that the even harmonics in the induced field play a more important part than the odd harmonics, and that the mixing of states between the