Local probing of jerky switching dynamics in Pb(Zr0.2Ti0.8)O3 thin films

Polarisation switching in ferroelectric materials is governed by the same competition between elasticity and disorder, which describes many systems from earthquake statistics to magnetic domain walls. The movement of the interface follows nonlinear creep and (de)pinning dynamics, with jerky individual events whose energy and size distributions are characterised by universal power laws. In ferroelectrics, domain nucleation and growth can be observed from nano to macroscale, providing a useful system in which this complex fundamental behaviour can be explored.

While past measurements have focused on average responses at the level of the whole sample, recent theoretical studies suggest that spatial resolution of the switching event distribution can provide important new information about the dynamic regime under observation.

Here, using piezoresponse force microscopy to follow polarisation reversal at the nanoscale in two epitaxially grown Pb(Zr0.2Ti0.8)O3 thin films, we show that the probability distribution of switching event sizes follows a power law with different exponents in samples with different disorder landscapes. Furthermore, we show how individual jerks attributed to domain wall motion and domain merging events contribute differently to the global switching dynamics.