  Ferroelectric switching and nanoscale domain dynamics were investigated using
atomic force microscopy on monocrystalline Pb(Zr0.2Ti0.8)O3 thin films.
Measurements of domain size versus writing time reveal a two-step domain growth
mechanism, in which initial nucleation is followed by radial domain wall motion
perpendicular to the polarization direction. The electric field dependence of
the domain wall velocity demonstrates that domain wall motion in ferroelectric
thin films is a creep process, with the critical exponent mu close to 1. The
dimensionality of the films suggests that disorder is at the origin of the
observed creep behavior.
