General features of the intrinsic ferroelectric coercive field

The value of the intrinsic ferroelectric coercive field is obtained independently, from general energy considerations and from the predictions of several models of the ferroelectric state. All predictions yield a value of the order of the depolarization field, which is equal to the spontaneous polarization divided by the dielectric permittivity, and are consistent with the recent measurements of the intrinsic ferroelectric coercive field in ultrathin Langmuir-Blodgett films of copolymers of polyvinylidene fluoride with trifluoroethylene. Prior studies succeeded only in measuring the much smaller extrinsic coercive fields, which are limited by nucleation processes and domain motion.