Ab initio study of samarium doped barium titanate

We used the density functional theory with spin polarization to investigate multifunctional properties of the Sm-doped BaTiO3 system (Ba1- (x) Sm (x) TiO3). The self-consistent calculation results were used to analyze the ferromagnetic and dielectric properties. The spontaneous electric polarization was estimated from the King-Smith and Vanderbilt theory and 1s core-hole absorbing atom was used to calculate the oxygen K-edge XANES spectra. The Hubbard correction has been considered over the rare-earth f-electrons. Results for x = 0.125 revealed a narrow band-gap energy, showing an enhanced ferroelectric character, with a spontaneous polarization higher than the reported for the pure tetragonal BaTiO3. On the other hand, the magnetic properties have been also confirmed, with a total magnetization value around 5.90 & mu;(B)/cell, which have been mainly ascribed to the inclusion of the Sm cation into the BT crystalline structure.