First principles study of the magnetism driven by cation defects in CeO2： the important role of O2p states

The magnetism driven by cation defects in undoped CeO2 bulk and thin films is studied by the density functional theory corrected for on-site Coulomb interactions （DFT＋U） with U = 5 eV for the Ce4f states and U = 7 eV for the O2p states. It is found that the Ce vacancies can induce a magnetic moment of the -4 gB/supercell, which arises mainly from the 2p hole state of the nearest neighbouring O atom （-1μB on per oxygen） to the Ce vacancy. The effect of the methodology is investigated, indicating that U = 7 eV for the O2p state is necessary to obtain the localized O2p hole state in defective ceria with cation vacancies.