Multiscaling Analysis of Ferroelectric Domain Wall Roughness

Using multiscaling analysis, we compare the characteristic roughening of ferroelectric domain walls in Pb(Zr0.2Ti0.8)O-3 thin films with numerical simulations of weakly pinned one-dimensional interfaces. Although at length scales up to L-MA >= 5 mu m the ferroelectric domain walls behave similarly to the numerical interfaces, showing a simple monoaffine scaling (with a well-defined roughness exponent zeta), we demonstrate more complex scaling at higher length scales, making the walls globally multiaffine (varying zeta at different observation length scales). The dominant contributions to this multiaffine scaling appear to be very localized variations in the disorder potential, possibly related to dislocation defects present in the substrate.