GRAIN-SIZE EFFECTS IN FERROELECTRIC SWITCHING

A model of ferroelectric switching that describes crystals composed of a large number of relatively small grains is presented. It is shown that, if the grain boundaries stop or significantly affect domain-wall growth, then the observed switching current transients will deviate from those predicted by the infinite-grain model of Ishibashi and Takagi. The model accounts for constant nucleation rate throughout the switching period and for constant domain-wall velocity. It is shown that at some time dependent only on the size of the grains and the domain-wall velocity, the switching-current transient changes from its small-time infinite-grain behavior to an exponential decay. The results are applied to two-dimensional Ising-model simulations. © 1990 The American Physical Society.