Electronic structure and orbital ordering of SrRu1-xTixO3:: GGA+U investigations

The electronic structures of the titanium-doped perovskite ruthenates SrRu1-xTixO3 with x=0.25, 0.50, and 0.75 are investigated using the generalized gradient approximation (GGA) as well as the GGA plus Hubbard U (GGA+U) scheme. It is found that the Ti substitutions with nearly empty 3d orbitals and relatively smaller atomic sizes significantly affect the orbital ordering patterns on the Ru sublattices. In addition, the observed metal-insulator transition upon change in the Ti dopant concentration is demonstrated to be driven primarily by the on-site Coulomb correlation U. The good agreement between the GGA+U results and the experimental observations reveals that the electron correlation plays an important role in SrRu1-xTixO3.