Rotation of easy axis in training effect and recovery of exchange bias in ferromagnet/antiferromagnet bilayers

TL;DR

This paper reports the first observation of easy axis rotation during training and recovery in ferromagnet/antiferromagnet bilayers, linking spin dynamics to changes in exchange bias.

Contribution

It introduces the novel observation of easy axis rotation during training and recovery in FeNi/FeMn bilayers, highlighting the role of irreversible antiferromagnetic spin motion.

Findings

Easy axis rotation occurs during training and recovery.

Rotation partly explains the training effect.

Irreversible antiferromagnetic spin motion is involved.

Abstract

For ferromagnet/antiferromagnet bilayers, rotation of the easy axis has been \textit{for the first time} observed during measurements of training effect and the recovery of exchange bias using FeNi/FeMn system. These salient phenomena strongly suggest irreversible motion of antiferromagnet spins during subsequent measurements of hysteresis loops. It is found that the rotation of the easy axis can partly account for the training effect and the recovery of the exchange bias.