Domain walls of ferroelectric BaTiO3 within the Ginzburg-Landau-Devonshire phenomenological model

TL;DR

This study systematically investigates domain walls in BaTiO3 ferroelectric phases using the Ginzburg-Landau-Devonshire model, providing detailed polarization, strain profiles, and energy estimates across temperature ranges.

Contribution

It offers a comprehensive analysis of mechanically compatible and electrically neutral domain walls in BaTiO3, including new insights into their thickness, energy, and structure in various ferroelectric phases.

Findings

Lowest energy walls identified for each phase.

Most domain walls have thickness below 1 nm.

Some walls resemble Bloch-like magnetic walls.

Abstract

Mechanically compatible and electrically neutral domain walls in tetragonal, orthorhombic and rhombohedral ferroelectric phases of BaTiO3 are systematically investigated in the framework of the phenomenological Ginzburg-Landau-Devonshire (GLD) model with parameters of Ref. [Hlinka and Marton, Phys. Rev. 74, 104104 (2006)]. Polarization and strain profiles within domain walls are calculated numerically and within an approximation leading to the quasi-one-dimensional analytic solutions applied previously to the ferroelectric walls of the tetragonal phase [W. Cao and L.E. Cross, Phys. Rev. 44, 5 (1991)]. Domain wall thicknesses and energy densities are estimated for all mechanically compatible and electrically neutral domain wall species in the entire temperature range of ferroelectric phases. The model suggests that the lowest energy walls in the orthorhombic phase of BaTiO3 are the 90-degree and 60-degree walls. In the rhombohedral phase, the lowest energy walls are the 71-degree and 109-degree walls. All these ferroelastic walls have thickness below 1 nm except for the 90-degree wall in the tetragonal phase and the 60-degree S-wall in the orthorhombic phase, for which the larger thickness of the order of 5 nm was found. The antiparallel walls of the rhombohedral phase have largest energy and thus they are unlikely to occur. The calculation indicates that the lowest energy structure of the 109-degree wall and few other domain walls in the orthorhombic and rhombohedral phases resemble Bloch-like walls known from magnetism.