The atomistic structures of MgO/SrTiO3(001) and BaO/SrTiO3(001) using simulated amorphization and recrystallization

Large-scale atomistic simulations of oxide interfaces have been performed where the thin film is forced to undergo a controlled amorphous transition prior to recrystallizing. The MO/SrTiO3(001) (M = Ba or Mg) systems explored using this simulation technique demonstrate markedly different structural characteristics owing to the difference in lattice parameter associated with each system. In particular regions of SrTiO3(001) (TiO2 terminated) supported MgO undergo a transformation into a pseudohexagonal type structure, reducing the lattice misfit from +7.4% to ca. -0.5 to -4%, whereas the +34% lattice misfit associated with the BaO/SrTiO3 system is reduced to -0.3% via a 45° rotation of the BaO with respect to the underlying SrTiO3. Moreover, the plane exposed by the SrTiO3(001) support (either SrO or TiO2) exacts a critical influence on the structure of the thin film. In particular, BaO, when supported on a TiO2 terminated SrTiO3, comprises a high concentration of dislocations. Conversely, for the analogous SrO terminated system no dislocations are present within the thin film.