Berlin 2005 – scientific programme

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M: Metallphysik

M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)

M 32.14: Poster

Monday, March 7, 2005, 14:30–16:30, Poster TU B

Ferroic multilayers with highly mobile interface charges — •Sibylle Gemming and Gotthard Seifert — Institut für Physikalische Chemie, TU Dresden, D-01062 Dresden.

The multilayered system SrTiO₃(001)|LaAlO₃(001) was investigated by density-functional band-structure calculations. For layers of equal and low thickness the optimised lattice constant equals the average of the ones of the two constituents. The system contains two different interface terminations with differing physical properties. For SrO(001)|AlO₂ (I) the interface spacing amounts to 1.90 Å, for TiO₂(001)|LaO (II) the spacing is reduced to 1.86 Å. A model system with equal amounts of both terminations, is electronically neutral with an indirect band gap of about 2 eV and a direct one of 2.5 eV at the local-density level. Model systems with only termination I exhibit holes, localised in the O-based valence band; for systems with pure termination II the additional electrons occupy a Ti-based conduction band with stronger dispersion. Projections of the electron density show that both types of charge carrier are confined to the heterophase boundary region, and that the valence band holes are spatially more strongly localised than the additional conduction band electrons.