Maxwellian charge on domain walls

Abstract

In situ transmission electron microscopy of domain motion in thinned BaTiO3 and KNbO3 shows that curved ferroelectric domains move more readily under low electric fields than do straight domain walls. We show that this relative motility arises because curved domain walls support a Maxwellian displacement charge and therefore experience a direct pressure that is proportional to the electric field E. Conversely, untilted charge-neutral domain walls experience a pressure proportional to E3 due to induced displacement charge, and therefore tend to resist motion at low fields. Any physical process that leads to an increase in density of the immobile charge-free domain walls, relative to the more mobile curved domain walls, could lead to an increase in overall resistance to domain switching, providing an intrinsic contribution to ferroelectric fatigue.