Scanning Oscillator Piezoresponse Microscopy: New Tools to Explore Domain Wall Dynamics

Dynamics of ferroelectric domain walls associated to domain wall switching are known to depend on bulk structure, being very sensitive to defects, chemical and structural pinning sites, as well as environmental conditions, modifying the electronic boundary conditions associated with screening dynamics. However, domain walls also show a sub-coercive field dynamics as a reversible motion, with vibrational states that strongly couple to local structure and composition of the domain wall. In this presentation, we will show a novel microscopy mode based on a multifrequency approach which allows us to quantify domain wall oscillations under applied sub-coercive electric field, while simultaneously disentangle electrostatic from net eletromechanical signals, which can introduce severe distortions on the net piezoelectric response around neutral domain walls. This technique allows quick visualization of domain wall displacement, their velocities and dependence on pre-existing domain configurations and defects. When applied to lead titanate, this technique shows significant oscillations of the 180° domain walls between the antiparallel c+/c- domains. Further, the displacement and velocities distinctly depend on existing a-c domain structures and relative orientations of domains. This technique can be readily applied to other heterostructures under a wide range of stimuli such as light, heat, force and bias.