Confinement effects in ultrathin perovskite films: ab initio calculations

E. Kotomin, D. Gryaznov, E. Blokhin, R.A. Evarestov*

* St. Petersburg University, Russia

Combining group-theoretical analysis and first-principles DFT calculations, we studied theoretically the antiferrodistortive (AFD) phase transition in ultrathin SrTiO₃ (001) films and compared it with the similar transition in the bulk. We have demonstrated that phonons soften at the M point of the surface Brillouin zone and analyzed the change in calculated electronic and phonon properties upon phase transition. We continue this study with calculations of thin films of perfect and defective BaZrO₃ with emphasis on a role of phonon contribution to the Gibbs free energy of defect formation.

The phonon DOS of bulk (top, 80-atom 3D supercell) and surface (bottom, 26-atom primitive 2D cell) before and after AFD phase transition in SrTiO3 (blue and red lines). From Blokhin et al, 2013, submitted — The phonon DOS of bulk (top, 80-atom 3D supercell) and surface (bottom, 26-atom primitive 2D cell) before and after AFD phase transition in SrTiO₃ (blue and red lines). From Blokhin et al, 2013, submitted

The phonon DOS of bulk (top, 80-atom 3D supercell) and surface (bottom, 26-atom primitive 2D cell) before and after AFD phase transition in SrTiO₃ (blue and red lines). From Blokhin et al, 2013, submitted

Publications:

E. Blokhin, E. Kotomin, A. Kuzmin, J. Purans, R. Evarestov, and J. Maier Theoretical modeling of the complexes of iron impurities and oxygen vacancies in SrTiO₃ Applied Physics Letters 102(11), 112913 (1–4) (2013). DOI: 10.1063/1.4796182

E. A. Kotomin, V. Alexandrov, D. Gryaznov, R. A. Evarestov, and J. Maier Confinement effects for ionic carriers in SrTiO₃ ultrathin films: first-principles calculations of oxygen vacancies Phys. Chem. Chem. Phys. 13(3), 923-926 (2011). DOI: 10.1039/c0cp01060j

V. E. Alexandrov, E. A. Kotomin, J. Maier, and R. E. Evarestov First-principles study of bulk and surface oxygen vacancies in SrTiO₃ crystal Eur. Phys. J. B 72(1), 53-57 (2009). DOI: 10.1140/epjb/e2009-00339-4