William H. Brumage

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...

Exchange Coupling of Neighboring Mn++ Ions in Mn++:ZnS Crystals

The magnetic susceptibilities have been measured over the temperature range of 20°–800°K for five ZnS crystals doped with Mn++ in varying concentrations from 0.5% to 7.5%. Above 77°K the magnetic data show considerable deviation from Curies law which can be explained by the antiferromagnetic coupling between the Mn++ ions situated at the nearest neighboring cation sites in the ZnS crystal. To account for the experimental results quantitatively, it is assumed that the numbers of clusters of various types are determined by statistics of random distribution and that the exchange operator can be taken as the simple isotropic form −2J (s1·s2). The observed susceptibilities can then be fitted to the theoretical values using J=−9±1 cm−1. Additional terms of the exchange operator such as the next‐nearest neighbor interaction, anisotropic exchange, and the biquadratic coupling term are discussed.

The dynamic Jahn–Teller effect applied to the temperature-dependent paramagnetic susceptibilities of Ti3+:Al2O3

The dynamic Jahn–Teller effect has been used in the analysis of the temperature-dependent paramagnetic susceptibilities of Ti3+:Al2O3. Two important changes have been made from the original analysis: (1) Parameters as determined from the dynamic Jahn–Teller effect are incorporated, and (2) All Van Vleck susceptibilities have been forced to sum to zero as required by quantum theory. The results of the analysis show that χ∥ contains a constant term of the order 1.22×10−8 emu/g that does not arise from Ti3+ singles. The data over the temperature range 18 to 100 K indicate that g∥1=2.54, a value 25% larger than that determined from the infrared Zeeman effect. It is possible to determine the perpendicular Van Vleck susceptibility for the ground state which is governed by the magnetic interaction of the lowest two energy levels with a substantial Jahn–Teller contribution. Finally, the suppression of the susceptibilities below 4.12 K can be modeled by a factor for the removal of singles from the susceptibilities...