Flexoelectricity and the polarity of complex ferroelastic twin patterns
Physical Review B
American Physical Society
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Salje, E., Li, S., Stengel, M., Gumbsch, P., & Ding, X. (2016). Flexoelectricity and the polarity of complex ferroelastic twin patterns. Physical Review B, 94 (2)https://doi.org/10.1103/PhysRevB.94.024114
We study, by means of an atomistic toy model, the interplay of ferroelastic twin patterns and electrical polarization. Our molecular dynamics simulations reproduce polarity in straight twin walls as observed experimentally. We show, by making contact with continuum theory, that the effect is governed by linear flexoelectricity. Complex twin patterns, with very high densities of kinks and/or junctions, produce winding structures in the dipolar field, which are reminiscent of polarization vortices. By means of a “cold shearing” technique, we produce patches with high vortex densities; these unexpectedly show a net macroscopic polarization even if neither the original sample nor the applied mechanical perturbation breaks inversion symmetry by itself. These results may explain some puzzling experimental observations of “parasitic” polarity in the paraelectric phase of BaTiO3 and LaAlO3.
EKHS is grateful to EPSRC for financial support (EP/K009702/1). SL and PG appreciate the support by Helmholtz Programme Science and Technology of Nanosystems (STN) (Vorhabensnumber 43.22.01). MS acknowledges support by MINECO-Spain through Grants No. FIS2013-48668-C2-2-P and No. SEV-2015-0496, and by Generalitat de Catalunya (2014 SGR301). X.D. appreciates the support of NSFC (51171140, 51231008, 51320105014, 51321003), the 973 Programs of China (2012CB619402), and 111 project (B06025).
External DOI: https://doi.org/10.1103/PhysRevB.94.024114
This record's URL: https://www.repository.cam.ac.uk/handle/1810/255819