Anomalous training effect of perpendicular exchange bias in Pt/Co/Pt/IrMn multilayers

TL;DR

This paper investigates the unique training effect in Pt/Co/Pt/IrMn multilayers with perpendicular magnetic anisotropy, revealing that the exchange bias decreases significantly with cycling while coercivity remains stable, linked to the reversal mechanism.

Contribution

It uncovers the anomalous training effect in perpendicular exchange bias and relates it to the magnetization reversal process in multilayers.

Findings

Exchange field decreases with cycling

Coercivity remains nearly unchanged

Training effect depends on reversal mechanism

Abstract

A new characteristic is observed in the training effect of perpendicular exchange bias. For Pt/Co/Pt/IrMn multilayers with perpendicular magnetic anisotropy, the magnetization reversal process is accompanied by pinned domain wall motion and the asymmetry of hysteresis loop is always equal to zero during subsequent measurements. It is interesting to find that the exchange field decreases greatly as a function of the cycling number while the coercivity almost does not change. It is clearly demonstrated that the training effect of perpendicular exchange bias strongly depends on the magnetization reversal mechanism of the ferromagnetic layer.