Stability of the unswitched ferroelectric polarization state in ultrathin epitaxial Pb(Zr,Ti)O3 in large electric fields

Abstract

A series of 50 ns-duration electric field pulses switches the polarization of a 35 nm-thick ferroelectric Pb(Zr,Ti)O3 film only at electric fields greater than 1.5 MV/cm, a factor of three higher than the low-frequency coercive field. There is no switching in response to a large number of pulses with lower fields, even when the total duration reaches several milliseconds. During longer microsecond-duration electric fields, however, switching progresses monotonically in both x-ray microdiffraction images and in electrical measurements. The difference between long and short electric field durations arises from domain nucleation and charge transport. A phase field model shows that the shrinking of the switched domain in the interval between pulses is a less important effect.