The effect of octahedral tilting of the ASnO3 (A = Ca, Sr, Ba) parent compound and bicolor ASnO3/A′SnO3 superlattice (A, A′ = Ca, Sr, Ba) is predicted from density-functional theory. In the ASnO3 parent compound, the structural phase transition as a function of the A-site cation size is correlated with the magnitude of the two octahedral tilting modes (a -a-c0 tilting and a0a0c+ tilting). The magnitude of octahedral tilting modes in the superlattices is analyzed quantitatively and is associated with that of constituent parent materials. ASnO3/A′SnO3 superlattices show the hybrid improper ferroelectricity resulting from the coupling of two octahedral tilting modes (a-a-c0 tilting and a0a0c+ tilting), which are also responsible for the structural phase transition from the tetragonal phase to the orthorhombic phase. Ferroelectricity due to A-site mirror symmetry breaking is a secondary order parameter for the orthorhombic phase transition in the bicolor superlattice and is related to the Γ5- symmetry mode. The coupling between tilting modes and the ferroelectric mode in the bicolor superlattice of ASnO3/A ′SnO3 is analyzed by group theory and symmetry mode analysis.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jul 8 2013|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics