Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 15: Thin Films and Nanostructures II

DF 15.4: Vortrag

Donnerstag, 26. März 2009, 11:40–12:00, WIL B321

Stabilization of out-of-plane polarization and head-to-head 180 domain walls in ferroelectric materials — •Kourosh Rahmanizadeh, Gustav Bihlmayer, and Stefan Blügel — Institut für Festkörperforschung & Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany

Experimental studies suggest that defects play an important role in ferroelectric materials. Employing density functional theory calculations based on the full-potential linearized augmented planewave method as implemented in the FLEUR code (www.flapw.de), we studied the polarization perpendicular to the surface of thin films of the ferroelectric perovskites BaTiO3 and PbTiO3. Without an electric field that compensates the depolarization field a polarization perpendicular to the surface is not stable, but we can stabilize an out-of-plane polarization with different types of defects at the surface. This mechanism can also be at work at head-to-head and tail-to-tail 180 domain walls, which can occur in these compounds. Although nominally a substantial extra charge is present at these surfaces or interfaces, the electronic properties are found to be very similar to the bulk of the perovskites.

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