2009/03/24 by K. Koch, Katrin Koch, R. O. Kuzian +6 · 8 citations
Chemistry · Materials Science · Mathematics · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Electric field #Electric field gradient #Electronic and Structural Properties of Oxides #Electronic structure #Hamiltonian (control theory) #Lattice (music) #Magnetic and transport properties of perovskites and related materials #Materials science #Mathematics #Physics #Quantum mechanics #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.80.125113
published in Physical Review B 80(12) (American Physical Society) · 10 pages, 4 figures
arxiv created 2009/03/24 · openalex publication_date 2009/09/16 · arxiv updated 2010/07/06 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze recent measurements [R. Blinc, V. V. Laguta, B. Zalar, M. Itoh, and H. Krakauer, J. Phys.: Condens. Matter 20, 085204 (2008)] of the electric field gradient on the oxygen site in the perovskites SrTiO3 and BaTiO3, which revealed, in agreement with calculations, a large difference in the electric field gradient (EFG) for these two compounds. In order to analyze the origin of this difference, we have performed density functional electronic-structure calculations within the local-orbital scheme FPLO. Our analysis reveals the counter-intuitive behavior that the EFG increases upon lattice expansion. Application of the standard model for perovskites, the effective two-level p\text\ensuremath-d Hamiltonian, cannot explain the experimentally observed and theoretically predicted behavior. In order to describe the EFG dependence correctly, a model beyond the usually sufficient p\text\ensuremath-d Hamiltonian is needed. We demonstrate that the counter-intuitive increase in the EFG upon lattice expansion can be explained by an s\text\ensuremath-p\text\ensuremath-d model containing the contribution of the oxygen 2s states to the crystal field on the Ti site. The proposed model extension is of general relevance for all related transition-metal oxides with similar crystal structure.