Dresden 2014 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 59: Computational Materials Modelling IX - Ferroelectrics

MM 59.3: Vortrag

Donnerstag, 3. April 2014, 16:15–16:30, IFW D

Polarization rotation at the ferroelectric domain walls of PbTiO₃ and PZT — •Anand Chandrasekaran^1,2, Dragan Damjanovic², Nava Setter², and Nicola Marzari¹ — ¹Theory and Simulation of Materials,École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland — ²Ceramics Laboratory, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

Polarization rotation and domain wall mobility are two key factors driving the development of state-of-the-art piezoelectric and ferroelectric devices. Ferroelectric domain walls in PbTiO₃ (PT) are thought to be predominantly of the ’Ising type’, where the polarization does not rotate but diminishes in magnitude close to the domain wall. However, our first-principles calculations show how tensile strains drastically increase polarization rotation in the vicinity of domain walls, that thus acquire both Néel and Bloch character. Large-scale calculations on PT and ordered lead zirconate titanate (PZT) show that the Bloch and Néel components of the polarization are long ranged, while the Ising component is short ranged and decays over 2-3 unit cells. Our analysis points to the possibility of tuning domain wall thickness through strain engineering. Such rotations enhance domain mobility through a reduction in the barrier energy for polarization reversal. Interestingly, the addition of Zr to PT delivers the required tensile strains, thus leading to the enhanced properties observed at the morphotropic phase boundary in PZT.