Controlled enhancement or suppression of exchange biasing using impurity $\delta$-layers

TL;DR

This study investigates how impurity $\delta$-layers inserted at various positions within a Co/IrMn bilayer can either enhance or suppress exchange biasing, revealing the influence of local magnetic and structural variations.

Contribution

It demonstrates that impurity doping can controllably modify exchange biasing, highlighting the role of bulk and interface effects in magnetic heterostructures.

Findings

Exchange bias can be either enhanced or suppressed depending on dopant species and position.

Magnetic impurities can enhance biasing even when placed far from the interface.

Local exchange and anisotropy variations within IrMn influence the spin structure.

Abstract

The effects of inserting impurity $\delta$-layers of various elements into a Co/IrMn exchange biased bilayer, at both the interface, and at given points within the IrMn layer a distance from the interface, has been investigated. Depending on the chemical species of dopant, and its position, we found that the exchange biasing can be either strongly enhanced or suppressed. We show that biasing is enhanced with a dusting of certain magnetic impurities, present at either at the interface or sufficiently far away from the Co/IrMn interface. This illustrates that the final spin structure at the Co/IrMn interface is not only governed by interface structure/roughness but is also mediated by local exchange or anisotropy variations within the bulk of the IrMn.