Abstract
Ferroelectric and ferroelastic domain walls play important roles in ferroelectric properties. However their couplings with flexoelectricity have been less understood. In this work we applied phase-field simulation to investigate the flexoelectric coupling with ferroelectric a/c twin structures in lead ziconate titanate (PZT) thin films. Local stress gradients were found to exist near twin walls that created both lateral and vertical electric fields through the flexoelectric effect, resulting in polarization inclinations from either horizontal or normal orientation, polarization rotation angles deviated from 90° and consequently highly asymmetric a/c twin walls. By tuning the flexoelectric strengths in a reasonable range from first-principle calculations, we found that the transverse flexoelectric coefficient has a larger influence on the polarization rotation than longitudinal and shear coefficients. As polar rotations that commonly occur at compositional morphotropic phase boundaries contribute to the piezoelectric enhancement, this work calls for further exploration of alternative strain-engineered polar rotations via flexoelectricity in ferroelectric thin films.
