Theoretical analysis based on the Landau-Ginzburg-Devonshire theory is used to show that the joint action of flexoelectric effect and rotostriction leads to a large spontaneous in-plane polarization (∼1-5 C/cm 2) and pyroelectric coefficient (∼10 -3 C/m 2K) in the vicinity of surfaces of otherwise non-ferroelectric ferroelastics, such as SrTiO 3, with static octahedral rotations. The origin of the improper polarization and pyroelectricity is an electric field we name flexo-roto field whose strength is proportional to the convolution of the flexoelectric and rotostriction tensors with octahedral tilts and their gradients. Flexo-roto field should exist at surfaces and interfaces in all structures with static octahedral rotations, and thus, it can induce surface polar states and pyroelectricity in a large class of otherwise nonpolar materials.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)