  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.
