Dynamics of ferroelectric 180° domain walls at engineered pinning centers

Abstract

The interaction between domain walls and pinning centers in ferroelectrics is of great interest from both fundamental and practical points of view. In this work, we show that, counter to intuition, the apparent velocity of domain walls can increase as the defect density increases. However, when we closely investigate the propagating front of the domain wall, we find that it is not unified but can be rough, indicating the presence of multiple nucleated domains in advance of the primary wall. We therefore ascribe the increased apparent velocity with defect density to actually derive from nucleation-aided motion. To further investigate the effect of engineered pinning centers, we spatially confined the defect regions and then propagated domain walls in that direction. We found that, given a sufficiently high defect density, walls can be pinned indefinitely at sub-threshold voltages. Finally, we outline a method to create domain wall propagation channels in which the wall is confined to a low defect region bordered by high defect density regions.

Interplay of domain structure and phase transitions: theory, experiment and functionality

“…In simulations of the idealized material, the energy barrier for removal of domains by collective polarization rotation by 45 • at the transition is small and previously induced elastic walls vanish [206]. In real samples the situation is more complex due to pinning of the domain walls at defects [362,363] or charge redistribution. Various transition paths have been observed even for single crystals of prototypical BaTiO 3 .…”

“…the overall piezoelectric response to an external stimulus X, such as pressure is given as d = d init + αX with d init the reversible piezoelectric response and α a measure for irreversibility of the response [430,431]. Key property for the utilization of extrinsic responses in applications are thus the domain wall mobility [157,432,433] and the fundamental understanding and control of pinning centers [363,429,434].…”