Berlin 2015 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 7: Focused Session on Ferroic Domain Walls II (DF with MA)
DF 7.6: Vortrag
Dienstag, 17. März 2015, 11:50–12:10, EB 107
Ab initio investigation of ferroelectric domain walls in barium fluorides — •Maribel Núñez Valdez and Nicola Spaldin — Materials Theory, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland
We present results of first-principles calculations of the ferroelectric domain walls in the layered perovskite-related barium fluorides, BaMF4 (M = Mg, Zn).
The ferroelectricity in the barium fluorides is driven by the softening of a single polar phonon mode consisting of both rotations of the MF6 octahedra and polar displacements of Ba cations. This so-called “geometric ferroelectricity” is a strikingly different mechanism from that in conventional ferroelectrics [C. Ederer and N.A. Spaldin Phys. Rev. B 74, 024102,2006].
Using density functional theory (DFT) within the general gradient approximation (GGA) we perform detailed structural relaxations of neutral domain walls (parallel to the polar c axis) and calculate the corresponding energies.
Based on comparisons of the total energies, we determine which domain wall orientations and configurations are most likely to form, and we compare their structural and electronic properties to those of domain walls in conventional ferroelectrics.
Finally we explore the strain dependence of the ferroelectric polarization, again comparing to that of conventional ferroelectrics.