Depolarizing-Field Effect in Strained Nanoscale Ferroelectric Capacitors and Tunnel Junctions

TL;DR

This paper investigates how depolarizing fields affect the stability and resistive switching behavior of strained nanoscale ferroelectric capacitors and tunnel junctions, using nonlinear thermodynamic modeling.

Contribution

It introduces a theoretical framework showing that homogeneous polarization can remain stable at the nanoscale in heterostructures with strained films and metal electrodes.

Findings

Homogeneous polarization remains stable at the nanoscale in certain heterostructures.

Depolarizing fields can enable resistive switching in ferroelectric tunnel junctions.

Resistance switching is governed by reciprocal capacitances of electrode screening charges.

Abstract

The influence of depolarizing field on the magnitude and stability of a uniform polarization in ferroelectric capacitors and tunnel junctions is studied using a nonlinear thermodynamic theory. It is predicted that, in heterostructures involving strained epitaxial films and metal electrodes, the homogeneous polarization state may remain stable against transformations into the paraelectric phase and into polydomain states down to the nanoscale. This result supports the possibility of depolarizing-field-related resistive switching in ferroelectric tunnel junctions with dissimilar electrodes. The resistance on/off ratio in such junctions is shown to be governed by the difference between the reciprocal capacitances of screening space charges in the electrodes.