Physical constraint and its consequence for hyperferroelectrics
Abstract
Hyperferroelectricity is a new phenomenon discovered recently [Garrity et al., Phys. Rev. Lett. 112, 127601 (2014)]. Based on a fourth-order Ginzburg-Landau energy expansion, we formulate a physical constraint that hyferroelectrics must satisfy. The constraint leads to a nonzero polarization under the open-circuit boundary condition as well as a stable electric state as the minimum of the free energy. The theory further reveals a guide principle on the search for new hyferroelectrics, i.e., they need to have a deep potential well and a small zero-field polarization. In addition, we show that an unstable longitudinal optical phonon is a natural consequence of the constraint. Prototypical ferroelectric BaTiO3, PbTiO3, and KNbO3 do not meet the physical constraint, and are not hyperferroelectrics.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 27, 2014
- Source ID
- 10.1063/1.4900480
Entities
People
- Huaxiang Fu
Organizations
- Office of Naval Research
- University of Arkansas