Origin of training effect of exchange bias in Co/CoO due to irreversible thermoremanent magnetization of the magnetically diluted antiferromagnet

TL;DR

This study reveals that the training effect in exchange bias of Co/CoO bilayers originates from the irreversible thermoremanent magnetization of the magnetically diluted antiferromagnetic layer, providing microscopic insight into the phenomenon.

Contribution

It demonstrates that the training effect of exchange bias is fundamentally linked to the thermoremanent magnetization behavior of the diluted antiferromagnet.

Findings

Thermoremanent magnetization decreases with hysteresis cycling.

Training effect correlates with reductions in thermoremanent magnetization.

Microscopic origin of exchange bias training effect identified.

Abstract

The irreversible thermoremanent magnetization of a sole, magnetically diluted epitaxial antiferromagnetic Co$_{1-y}$O(100) layer is determined by the mean of its thermoremanent magnetizations at positive and negative remanence. During hysteresis-loop field cycling, thermoremanent magnetization exhibits successive reductions, consistent with the training effect (TE) of the exchange bias measured for the corresponding Co$_{1-y}$O(100)/Co bilayer. The TE of exchange bias is shown to have its microscopic origin in the TE of the irreversible thermoremanent magnetization of the magnetically diluted AFM.