Abstract
We report on theoretical and experimental investigation of -site-driven ferroelectricity in ferromagnetic thin films grown on substrates. Structural analysis and density-functional theory calculations show that epitaxial strain stretches the rhombohedral crystal lattice along the direction, triggering a displacement of the -site La ions in the double-perovskite lattice. The lattice distortion and the -site displacements stabilize a ferroelectric polar state in ferromagnetic crystals. The ferroelectric state only appears in the rhombohedral phase, where and octahedral tilting is inhibited by the threefold crystal symmetry. Electron localization mapping showed that covalent bonding with oxygen and orbital lone-pair formation are negligible in this material.
3 More- Received 17 December 2014
- Revised 29 January 2015
DOI:https://doi.org/10.1103/PhysRevB.91.134107
©2015 American Physical Society