Exploring vertex interactions in ferroelectric flux-closure domains.

Using piezoresponse force microscopy, we have observed the progressive development of ferroelectric flux-closure domain structures and Landau-Kittel-type domain patterns, in 300 nm thick single-crystal BaTiO3 platelets. As the microstructural development proceeds, the rate of change of the domain configuration is seen to decrease exponentially. Nevertheless, domain wall velocities throughout are commensurate with creep processes in oxide ferroelectrics. Progressive screening of macroscopic destabilizing fields, primarily the surface-related depolarizing field, successfully describes the main features of the observed kinetics. Changes in the separation of domain-wall vertex junctions prompt a consideration that vertex-vertex interactions could be influencing the measured kinetics. However, the expected dynamic signatures associated with direct vertex-vertex interactions are not resolved. If present, our measurements confine the length scale for interaction between vertices to the order of a few hundred nanometers.