Electromechanical properties of the 180{\deg} domain wall in PbTiO3

Abstract

We analyze the electromechanical response of the 180 degree ferroelectric domain wall in tetragonal PbTiO3 by combining first-principles calculations with a Landau-Ginzburg-Devonshire (LGD) description. Using regular multidomain structures with varying domain-wall density, we extract polarization profiles and lattice distortions and map them onto the continuum model to determine conventional (homogeneous) and gradient (inhomogeneous) electrostriction. Conventional electrostriction yields only a small negative length change of the sample, whereas gradient electrostriction--arising from the coupling between strain and polarization gradients--produces a positive contribution nearly an order of magnitude larger and localized at the wall core. Our results demonstrate that gradient electrostriction dominates the electromechanical response of 180 degree walls in PbTiO3, supporting its inclusion in LGD models that stabilize Bloch-type domain wall structures.