Critical Thickness for Antiferroelectricity in PbZrO3

Ferroelectrics and antiferroelectrics appear to have just the opposite behavior upon scaling down. Below a critical thickness of just a few nanometers the ferroelectric phase breaks into nanodomains that mimic electric properties of antiferroelectrics very closely. On the other hand, antiferroelectric thin films were found to transition from the antiferroelectric behavior to a ferroelectric one under certain growth conditions. At present, the origin of such a transition is controversial. Here, we use accurate first-principles-based finite-temperature simulations to predict the existence of a critical thickness for antiferroelectricity in the most celebrated antiferroelectric, PbZrO3. The origin of this effect is traced to the intrinsic surface contribution that has been previously overlooked. The existence of a critical thickness below which the antiferroelectric phase is replaced with a ferroelectric one not only complements the discovery of a critical thickness for ferroelectricity, but also suggests that ferroelectricity and antiferroelectricity are just two opposite manifestations of the same phenomenon: the material's tendency to develop a long-range order. Nanoscaling offers the opportunity to manipulate this order.