Rotation of tensor axes in the EPR of Cr 3+ in monoclinic sites

Abstract

Calculations are reported for the orientation of g and D tensors for Cr 3+ ions in sites of low point symmetry based upon a crystal field model which neglects spin-spin coupling and which also assumes small departures from D 4h symmetry. It is found that upon lowering the point symmetry from D 2h to C 2h, the principal g and D axes are rotated together about the twofold axis by a finite angle (δ/2) which is determined by the low symmetry components of the crystal field. Within the limits of the model, there is no restriction on the magnitude of the rotation.