Regensburg 2010 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 3: Poster I: Nano- and microstructured dielectrics, surfaces and interfaces, dielectric composites

DF 3.3: Poster

Montag, 22. März 2010, 15:00–17:30, Poster D1

DFT modelling of SrO(SrTiO₃)_n Ruddlesden-Popper surfaces
— •Matthias Zschornak^1,2, Emanuel Gutmann¹, Torsten Weißbach^1,2, Tilmann Leisegang¹, Dirk C. Meyer^1,3, and Sibylle Gemming² — ¹Nachwuchsgruppe Nanostrukturphysik, Institute of Structural Physics, TU Dresden, Germany — ²Institute of Ion Beam Physics and Materials Research, FZ Dresden-Rossendorf, Germany — ³Institute of Experimental Physics, TU Bergakademie Freiberg, Germany

Strontium titanate (SrTiO₃) is an oxide crystallizing with cubic perovskite-type of structure that exhibits a high tunability of dielectric, electric, mechanical and optical properties by means of defects. Apart from dopants, also intrinsic oxygen vacancies or ordered stacking faults, e.g. Ruddlesden-Popper (RP) phases SrO(SrTiO₃)_n, may influence these properties.
We have investigated the surface energy, relaxation and electronic properties of such RP surfaces up to n = 3 in comparison to ’pure’ SrTiO₃ by means of density-functional theory for ⟨ 001⟩ and ⟨ 100⟩ directions and with all possible perfect crystal terminations. We find a significant influence of the surface-near SrO-OSr stacking fault on surface energies and rumpling. Migrating surface states decrease the band gap of TiO₂ terminations but all terminations show insulating character. A detailed discussion of surface-near relaxations will be presented.