Determination of the Spin–Orbit and Trigonal-Field Splittings of the 5E State of Fe2+ in ZnO, ZnS, CdS, ZnSe, CdSe, ZnTe, and CdTe Crystals by Magnetic Susceptibilities

The magnetic susceptibilities of the Fe²⁺:ZnSe, Fe²⁺:CdSe, Fe²⁺:ZnTe, Fe²⁺:CdTe, Fe²⁺:ZnS, Fe²⁺:CdS, and Fe²⁺:ZnO crystals have been measured over the temperature range of 2–300°K in order to determine the spin–orbit and trigonal‐field (for CdS and ZnO) splittings of the ground orbital state ${}^{5}E$ of Fe²⁺ in the crystal lattice. The first five crystals are magnetically isotropic with no detectable trigonal‐field effects, and their susceptibilities tend toward constant values at very low temperature. From the temperature dependence of the susceptibility, we obtain the spacings of the $A_1$ and $T_1$ component of the ${}^{5}E$ group of the first five crystals as 12, 12, 16, 18, and 15 cm⁻¹, respectively. These results give spin–orbit coupling constants $\text{|\hspace{0.17em}λ\hspace{0.17em}|\hspace{0.17em}=\hspace{0.17em}85, 81, 96, 99}$ , and 99 cm⁻¹, respectively, when used in conjunction with the optical data of the ${}^5{\mathrm{E-}}^5{T}_2$ transitions. The Fe²⁺:CdS crystals show a small magnetic anisotropy but otherwise similar susceptibility data which yield 16 cm⁻¹ for the $A_1{\mathrm{-T}}_1$ spacing, 1 cm⁻¹ for the trigonal‐field splitting of $T_1,\mathrm{and}\text{|\hspace{0.17em}λ\hspace{0.17em}|\hspace{0.17em}=\hspace{0.17em}97}{\mathrm{cm}}^{\text{−1}}$ . For the case of Fe²⁺:ZnO, the magnetic anisotropy is much larger, and the $T_1$ levels split into two components $A_2$ and $E$ which are 8 and 18 cm⁻¹, respectively, above the $A_1$ ground state as determined from the magnetic data.