ENERGY-LEVELS OF CO2+ IN COF2 AND CSCOCL3

Neutron scattering measurements have been made of the high-energy exci tonic excitations of Co2+ ions in CoF2 and CsCoCl3. The measurements w ere performed with the HET direct geometry time-of-flight spectrometer on the ISIS pulsed neutron source at the Rutherford Appleton Laborato ry. In the case of CoF2 the results are consistent with previous estim ates of the crystal-held and spin-orbit parameters, but for CsCoCl3 th ere are marked discrepancies. The results can be fitted by adjusting t he crystal-held parameters, but this has the consequence that the exch ange interactions between the spins in CsCoCl3 are anisotropic.