Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale

TL;DR

This paper demonstrates a reproducible tunneling electroresistance effect in nanoscale ferroelectric BaTiO3 tunnel junctions, showing significant resistance change upon polarization reversal, with potential applications in non-volatile memory devices.

Contribution

The study provides direct nanoscale visualization and control of polarization and tunneling current, establishing a reproducible electroresistance effect in epitaxial BaTiO3 films at room temperature.

Findings

Resistance change of about two orders of magnitude upon polarization reversal

Nanoscale control of polarization and tunneling current on 20 nm scale

Room temperature operation of ferroelectric tunnel junctions

Abstract

Stable and switchable polarization of ferroelectric materials opens a possibility to electrically control their functional behavior. A particularly promising approach is to employ ferroelectric tunnel junctions where the polarization reversal in a ferroelectric barrier changes the tunneling current across the junction. Here, we demonstrate the reproducible tunneling electroresistance effect using a combination of Piezoresponse Force Microscopy (PFM) and Conducting Atomic Force Microscopy (C-AFM) techniques on nanometer-thick epitaxial BaTiO3 single crystal thin films on SrRuO3 bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by the direct nanoscale visualization and control of polarization and tunneling current in BaTiO3 films. The obtained results show a change in resistance by about two orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature. These results are promising for employing ferroelectric tunnel junctions in non-volatile memory and logic devices, not involving charge as a state variable.