  The static configuration of ferroelectric domain walls was investigated using
atomic force microscopy on epitaxial PbZr0.2Ti0.8O3 thin films. Measurements of
domain wall roughness reveal a power law growth of the correlation function of
relative displacements B(L) ~ L^(2zeta) with zeta ~ 0.26 at short length scales
L, followed by an apparent saturation at large L. In the same films, the
dynamic exponent mu was found to be ~ 0.6 from independent measurements of
domain wall creep. These results give an effective domain wall dimensionality
of d=2.5, in good agreement with theoretical calculations for a two-dimensional
elastic interface in the presence of random-bond disorder and long range
dipolar interactions.
