Quantitative description of the azimuthal dependence of the exchange bias effect

TL;DR

This paper provides a quantitative model that accurately describes the azimuthal dependence of the exchange bias effect by incorporating interface spin disorder, resolving previous discrepancies between theory and experiment.

Contribution

It introduces a modified Meiklejohn and Bean model that accounts for interface spin disorder, achieving near-perfect agreement with experimental data.

Findings

Model accurately reproduces exchange bias and coercive fields across 360° azimuthal range.

Interface spin disorder is identified as the key factor in exchange bias behavior.

Demonstrated with CoFe/IrMn bilayer and MOKE measurements.

Abstract

While the principal features of the exchange bias between a ferromagnet and an antiferromagnet are believed to be understood, a quantitative description is still lacking. We show that interface spin disorder is the main reason for the discrepancy of model calculations versus experimental results. Taking into account spin disorder at the interface between the ferromagnet and the antiferromagnet by modifying the well known Meiklejohn and Bean model, an almost perfect agreement can be reached. As an example this is demonstrated for the CoFe/IrMn exchange biased bilayer by analyzing the azimuthal dependence of magnetic hysteresis loops from MOKE measurements. Both, exchange bias and coercive fields for the complete 360$^\circ$ angular range are reproduced by our model.