On the key role of oxygen vacancies electromigration in the memristive response of ferroelectric devices

TL;DR

This paper reveals that oxygen vacancy electromigration and ferroelectric polarization modulation jointly determine the memristive behavior of ferroelectric devices, with implications for neuromorphic computing.

Contribution

It introduces a phenomenological model that captures the combined effects of interface barrier modulation and oxygen vacancy electromigration in ferroelectric memristors.

Findings

Simulation reproduces resistance relaxation phenomena

Oxygen vacancy electromigration influences device hysteresis

Potential for combining non-volatile and volatile resistive states

Abstract

Ferroelectric memristors are intensively studied due to their potential implementation in data storage and processing devices. In this work we show that the memristive behavior of metal/ferroelectric oxide/metal devices relies on the competition of two effects: the modulation of metal/ferroelectric interface barriers by the switchable ferroelectric polarization and the electromigration of oxygen vacancies, with the depolarizing field playing a fundamental role in the latter. We simulate our experimental results with a phenomenological model that includes both effects and we reproduce several non-trivial features of the electrical response, including resistance relaxations observed after external poling. Besides providing insight into the underlying physics of these complex devices, our work suggests that it is possible to combine non-volatile and volatile resistive changes in single ferroelectric memristors, an issue that could be useful for the development of neuromorphic devices.