Ferroionic states in ferroelectric thin films

TL;DR

This paper develops an analytical model describing ferroionic states in ferroelectric thin films, highlighting their sensitivity to environmental factors and providing insights into their thermodynamic and kinetic behaviors.

Contribution

It introduces a comprehensive analytical framework combining ferroelectric and ionic surface interactions, advancing understanding of ferroionic states in thin films.

Findings

Ferroionic states are highly sensitive to temperature and external electric potential.

The model predicts a continuum of mixed states influenced by surface chemistry.

Insights into the thermodynamic stability of ferroionic states are provided.

Abstract

The electric coupling between surface ions and bulk ferroelectricity gives rise to a continuum of mixed states in ferroelectric thin films, exquisitely sensitive to temperature and external factors, such as applied voltage and oxygen pressure. Here we develop the comprehensive analytical description of these coupled ferroelectric and ionic ("ferroionic") states by combining the Ginzburg-Landau-Devonshire description of the ferroelectric properties of the film with Langmuir adsorption model for the electrochemical reaction at the film surface. We explore the thermodynamic and kinetic characteristics of the ferroionic states as a function of temperature, film thickness, and external electric potential. These studies provide a new insight into mesoscopic properties of ferroelectric thin films, whose surface is exposed to chemical environment as screening charges supplier.