RESUMO
The electronic structure and magnetic properties of Co-doped CeO(2) are theoretically investigated by first principles calculations based on the density functional theory + U (DFT+U) methods, using the WIEN2k package. With the presence of oxygen vacancies (V(O)) in CeO(2), d and f orbits of Ce are obviously pulled closer to the Fermi level, but without spin polarization. On the other hand, in Co-doped CeO(2), V(O) defects can lead to strong ferromagnetic coupling between the nearest neighboring Co ions. Such ferromagnetic exchange coupling is mainly attributed to spin splitting of Co 3d states, via electrons trapped in V(O). The results provide direct evidence for the F-center mediated exchange interaction in oxide-based magnetic semiconductors.