Effect of surface ionic screening on polarization reversal and phase diagrams in thin antiferroelectric films for information and energy storage
The emergent behaviors in antiferroelectric thin films due to a coupling between surface electrochemistry and intrinsic polar instabilities are explored within the framework of the modified 2-4-6 Kittel-Landau-Ginzburg-Devonshire (KLGD) thermodynamic approach. Using phenomenological parameters of the KLGD potential for a bulk antiferroelectric (PbZrO3) and a Stephenson-Highland (SH) approach, we study the role of surface ions with a charge density proportional to the relative partial oxygen pressure on the dipole states and their reversal mechanisms in the antiferroelectric thin films. The combined KLGD-SH approach allows to delineate the boundaries of antiferroelectric, ferroelectric-like antiferroionic and electret-like paraelectric states as a function of temperature, oxygen pressure, surface ions formation energy and concentration, and film thickness. This approach also allows the characterization of the polar and antipolar orderings dependence on the voltage applied to the antiferroelectric film, and the analysis of their static and dynamic hysteresis loops. The applications of the antiferroelectric films covered with surface ion layer for energy and information storage are explored.