CR2+-CAO JAHN-TELLER SYSTEM

Acoustic paramagnetic resonance from Cr2+ ions in CaO has been observed at frequencies close to 9 GHz and detailed results have been obtained with the magnetic field H directed along the (111) direction. With this direction for H, the peaks in the APR spectrum are expected to arise from those Cr2+ ions occupying zero-strain sites as the Hamiltonian displays C3i symmetry. An analysis of the data obtained is given and it is shown that the results can be fitted to a multimode Jahn-Teller model. Values for the basic crystal-field parameters and an energy-level diagram for zero-strain sites are obtained.