Zeeman interaction and Jahn-Teller effect in the Gamma(8) multiplet

Abstract

We present a thorough analysis of the interplay of magnetic moment and the Jahn-Teller effect in the Γ8 cubic multiplet. We find that in the presence of the dynamical Jahn-Teller effect, the Zeeman interaction remains isotropic, whereas the g and G factors can change their signs. The static Jahn-Teller distortion also can change the sign of these g factors as well as the nature of the magnetic anisotropy. Combining the theory with state-of-the-art ab initio calculations, we analyzed the magnetic properties of Np4+ and Ir4+ impurity ions in a cubic environment. The calculated g factors of the Np4+ impurity agree well with experimental data. The ab initio calculation predicts a strong Jahn-Teller effect in Ir4+ ion in the cubic environment and the strong vibronic reduction of g and G factors.