While an ideal antiparallel ferroelectric wall is considered a unit cell in width (~0.5nm), we show using phase field modeling that the threshold field for moving this wall dramatically drops by 2-3 orders of magnitude if the wall were diffuse by only ~2-3nm. Since antiparallel domain walls are symmetry allowed in all ferroelectrics, and since domain wall broadening on nanometer scale is widely reported in literature, this mechanism is generally applicable to all ferroelectrics.
@article{arxiv.0806.1510,
title = {Threshold fields for antiparallel ferroelectric domain wall motion},
author = {Samrat Choudhury and Yulan Li and Nozomi Odagawa and Aravind Vasudevarao and L. Tian and Pavel Capek and Volkmar Dierolf and Anna N. Morozovska and Eugene A. Eliseev and Long-qing Chen and Yasuo Cho and Sergei Kalinin and Venkatraman Gopalan},
journal= {arXiv preprint arXiv:0806.1510},
year = {2008}
}