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 5E 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 A1 and T1 component of the 5E group of the first five crystals as 12, 12, 16, 18, and 15 cm−1, respectively. These results give spin–orbit coupling constants | λ | = 85, 81, 96, 99, and 99 cm−1, respectively, when used in conjunction with the optical data of the 5E−5T2 transitions. The Fe2+:CdS crystals show a small magnetic anisotropy but otherwise similar susceptibility data which yield 16 cm−1 for the A1−T1 spacing, 1 cm−1 for the trigonal-field splitting of T1, and | λ | = 97 cm−1. For the case of Fe2+:ZnO, the magnetic anisotropy is much larger, and the T1 levels split into two components A2 and E which are 8 and 18 cm−1, respectively, above the A1 ground state as determined from the magnetic data.