Atomic-scale compensation phenomena at polar interfaces

TL;DR

This paper investigates atomic-scale compensation mechanisms at polar interfaces, revealing ionic screening and interfacial charge generation as key factors influencing ferroelectric properties at the nanoscale.

Contribution

It provides the first experimental evidence of ionic screening at ferroelectric interfaces and explores how interfacial charge compensates polarization in ultrathin ferroelectrics.

Findings

Evidence for ionic screening at ferroelectric interfaces

Interfacial charge generated by oxygen vacancies

Implications for ultrathin ferroelectric device performance

Abstract

The interfacial screening charge that arises to compensate electric fields of dielectric or ferroelectric thin films is now recognized as the most important factor in determining the capacitance or polarization of ultrathin ferroelectrics. Here we investigate using aberration-corrected electron microscopy and density functional theory how interfaces cope with the need to terminate ferroelectric polarization. In one case, we show evidence for ionic screening, which has been predicted by theory but never observed. For a ferroelectric film on an insulating substrate, we found that compensation can be mediated by interfacial charge generated, for example, by oxygen vacancies.