Zeeman Effect of Cr3+ in ZnAl2O4

Abstract

The Zeeman effect for Cr³⁺ in the trigonally distorted octahedral site of ZnAl₂O₄ has been measured for applied fields up to 32 kOe. The lines whose splittings were observed correspond to the transitions ${}^2\mathrm{E(Ē)}$ and ${}^2{\text{E(2Ā)→}}^4{A}_2\mathrm{(Ē)}$ and ${}^4{A}_2\text{(2Ā)}$ (the $R$ lines) in fluorescence. For $H$ applied along the crystal [001] axis all four sites in the unit cell are equivalent and one of the upper‐state $g$ values is zero. Under these circumstances some of the observed lines correspond to a direct observation of the ground‐state splittings in the nonlinear region of level crossing. The anisotropy of the upper and lower state $g$ factors was determined from experiments in which the sample was rotated around a [110] direction with the magnetic field applied perpendicular to the rotation direction. The $g$ values determined from the spectra are compared with calculated values from crystal‐field theory given in the literature.