Ferroelectric domain walls (FDWs) are usually considered to be of Ising type, but there have been suggestions in recent years that Bloch-type FDWs are also possible in some cases, e.g., in the rhombohedral phase of BaTiO 3. The mechanically compatible and electrically neutral FDWs in rhombohedral BaTiO 3 are of 71 a, 109 a, and 180 a type. We have investigated these FDWs based both on first-principles calculations and on a Ginzburg-Landau-Devonshire (GLD) model. The results from both approaches confirm the Ising nature of the 71 a FDW and the Bloch nature of the 180 a FDW, and predict both Ising-type and Bloch-type FDWs are possible for the 109 a case. Considering the relatively small rhombohedral strain in BaTiO 3, the competition between the energies of Bloch and Ising FDWs can be discussed in terms of a picture in which a Bloch wall is regarded as being composed of a pair of smaller-angle Ising ones. A reduction by 40% in the parameters describing the gradient term in the GLD model brings it into better agreement with the first-principles results for detailed properties such as the energies and widths of the FDWs.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 22 2012|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics