Ab initio study of the ferroelectric strain dependence and 180${}^{\circ }$ domain walls in the barium metal fluorides BaMgF${}_4$ and BaZnF${}_4$

Abstract

We investigate the strain dependence of the ferroelectric polarization and the structure of the ferroelectric domain walls in the layered perovskite-related barium fluorides, BaMF${}_4$ (M=Mg, Zn). The unusual "geometric ferroelectricity" in these materials is driven by the softening of a single polar phonon mode consisting of rotations of the MF${}_6$ octahedra accompanied by polar displacements of the Ba cations, and in contrast to conventional ferroelectrics involves minimal electronic rehybridization. We therefore anticipate a different strain dependence of the polarization, and alternative domain wall structures compared with those found in conventional ferroelectric materials. Using first-principles calculations based on density functional theory (DFT) within the general gradient approximation (GGA), we calculate the variation of the crystal structure and the ferroelectric polarization under both compressive and tensile strain. We perform structural relaxations of neutral domain walls between oppositely oriented directions of the ferroelectric polarization and calculate their corresponding energies to determine which are most likely to form. We compare our results to literature values for conventional perovskite oxides to provide a source of comparison for understanding the ferroelectric properties of alternative non-oxide materials such as the barium fluorides.

8 pages, 7 figures, 3 tables

References in corpus (4)

• Effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics
• Structural Domain Walls in Polar Hexagonal Manganites
• Origin of ferroelectricity in the multiferroic barium fluorides BaMF4
• Domain walls in a perovskite oxide with two primary structural order parameters: first-principles study of BiFeO${}_3$

Cited by in corpus (5)

• Prediction of a controllable Weyl semi-metallic phase in inversion-asymmetric BiSb
• Direct magnetization-polarization coupling in BaCuF${}_4$ fluoride
• Polarity of domain boundaries in nonpolar materials derived from order parameter and layer group symmetry
• Origin and evolution of ferroelectricity in the layered rare-earth-titanate, $R_2$Ti${}_2$O${}_7$, Lichtenberg phases
• Large geometric polarization and magnetic behavior in the multiferroic quasi-2D SrNiF${}_4$ fluoride