  The electronic structure of the cubic and (high pressure) hexagonal phases of
Eu2O3 have been investigated by mean of full potential linearized augmented
plane wave calculations, within the LDA+U method. For the cubic phase, the
comparison between ferromagnetic and antiferromag- netic calculations shows
that the exchange interaction is very weak and is therefore expected to have a
negligible effect on the magnetic susceptibility. This is consistent with the
experimental behavior of the susceptibility of solid solutions of Eu2O3 into
A2O3 (A=Y, Lu, Sc). The calcu- lations performed for the high pressure
hexagonal phase, on the other hand, show that there is an antiferromagnetic
exchange interaction between nearest neighbor Eu ions, which should have a
sizeable effect on the susceptibility. Our results allow us to discuss the
existing theories.
