Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 25: Poster Session

MM 25.28: Poster

Mittwoch, 29. März 2006, 15:30–17:30, P4

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

The multilayered system SrTiO3(001)∣LaAlO3(001) was investigated by density-functional band-structure calculations. The system contains two interface terminations with differing physical properties. For SrO(001)∣AlO2 (I) the interface spacing amounts to 190 pm, for TiO2(001)∣LaO (II) the spacing is reduced to 186 pm. 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. Due to the complex strain state the dielectric properties of the system exhibit a pronounced asymmetry, which is enhanced by the presence of the interfaces.