Large time-dependent coercivity and resistivity modification under sustained voltage application in a Pt/Co/AlOx/Pt junction

TL;DR

This study investigates how sustained voltage influences coercivity and resistivity in a Pt/Co/AlOx/Pt junction, revealing reversible, time-dependent modifications likely driven by electrochemical processes and oxygen vacancy migration.

Contribution

It demonstrates that high bias voltages induce significant, reversible, and time-dependent changes in coercivity and resistivity, with a proposed model explaining the logarithmic development.

Findings

High bias voltages cause enhanced coercivity modifications.

Resistivity changes are reversible and occur over minutes.

Oxygen vacancy migration likely explains the observed effects.

Abstract

The coercivity and resistivity of a Pt/Co/AlOx/Pt junction are measured under sustained voltage application. High bias voltages of either polarity are determined to cause a strongly enhanced, reversible coercivity modification compared to low voltages. Time-resolved measurements show a logarithmic development of the coercive field in this regime, which continues over a period as long as thirty minutes. Furthermore, the resistance of the dielectric barrier is found to change strongly and reversibly on the same time scale, suggesting an electrochemical process is taking place within the dielectric. It is argued that the migration of oxygen vacancies at the magnet/oxide interface could explain both the resistance variation and the enhanced electric field effect at high voltages. A thermal fluctuation aftereffect model is applied to account for the observed logarithmic dependence.