Temperature dependence of the EFG at Cd-doped Lu_2O_3: How ab initio calculations can complement PAC experiments

摘要

We report an ab initio study of the temperature dependence of the electric-field gradient (EFG) tensor at Cd impurities replacing cations in Lu_2O_3. Calculations were performed with the Full-Potential Linearized-Augmented Plane Wave method that allows us to treat the electronic structure and the processes induced by the impurity in the host-lattice without the use of external parameters. In this new insight, the EFG thermal dependence arises from the ionization of an impurity acceptor level introduced in the band-gap of Lu_2O_3 by Cd impurities, in good agreement with a previously proposed two state model.