Abstract
Ferroelectric materials contain domains of ordered electric dipoles, separated by domain walls, that can undergo polarisation switching under externally applied electric fields. The domain switching dynamics in ferroelectric materials plays an essential role in their application to electronic and electro-optic de- vices. Previous studies suggest that the switching occurs largely through domain wall motion which is explained from the viewpoint of statistical physics on surface growth as the behaviour of a pinned elas- tic interface. We perform molecular dynamics simulations to investigate the domain switching process and quantitatively estimate the switching speed of anti-parallel 180° domains in ferroelectric, tetragonal BaTiO3 perfect single crystals at room temperature using the core-shell model. We observe an unprece- dented, non-linear increase in the domain switching speed caused by the nucleation of new domains within the switching domain. We determine the strength of the electric field to evoke nucleation of new domains and show that the nucleated domains diffuse into nearby favourable domains when the electric field is removed. Furthermore, we discuss the prominence of domain nucleations during ferroelectric switching.
Highlights
Ferroelectric materials are indispensable in a countless number of industrial and scientific applications due to their dielectric, piezoelectric, pyroelectric, electro-optic and electrical hysteresis properties[1]
It is suggested that the typical ferroelectric switching is largely governed by a simple, universal mechanism of intrinsic domain wall motion and that, even in the absence of defects, the electric field dependence of the domain wall speed can be described with a non-linear creep-like region and a depinning-like region[10]
We find that the ferroelectric switching is characterized not just by the domain wall motion but more importantly by the nucleations and growth of new domains within the reversal domain
Summary
Ferroelectric materials are indispensable in a countless number of industrial and scientific applications due to their dielectric, piezoelectric, pyroelectric, electro-optic and electrical hysteresis properties[1]. The electrical hysteresis loops are characteristic of ferroelectric materials as they possess spontaneous electric polarisation, in a definite range of temperature, that can be switched to two or more stable states by application of an external electric field. This change in the polarisation direction is remnant if the electric field is sufficiently high. It is suggested that the typical ferroelectric switching is largely governed by a simple, universal mechanism of intrinsic domain wall motion and that, even in the absence of defects, the electric field dependence of the domain wall speed can be described with a non-linear creep-like region and a depinning-like region[10]. Equation 1 can be seen as a generalized formulation of the Merz’s law[2, 10], ν exp −
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