Exchange bias through a Cu interlayer in an IrMn/Co system

Abstract

Ferromagnetic resonance FMR and magnetization MAG measurements were used to study the exchange interaction between the antiferromagnetic and ferromagnetic layers in an IrMn/Cu/Co system as a function of the Cu spacer thickness. Although the experimental angular variations of the exchange-bias fields Heb FMR and Heb MAG coincide, the coupling strengths J and the Co layers’ anisotropy fields HU, obtained via numerical simulations, are different. For all Cu thicknesses JFMR >JMAG and HU FMR< HU MAG. The exchange coupling decreases exponentially with the spacer thickness and is a short-range interaction. These characteristics were explained in the framework of a model considering polycrystalline magnetic layers with independent easy axis distributions, taking into account the rotatable anisotropy. The role of antiferromagnetic grains at the interface with different sizes and different magnetic stabilities is essential for understanding the behavior of this exchange-biased system.