Critical angle behaviour of exchange bias and coercivity with field angle in exchange coupled CoFe/MnIr bilayers

摘要

In exchange coupled ferromagnetic (F)/ antiferromagnetic (AF) bilayers, the exchange bias field (H{sub}(ex)) has been appeared at thicker AF thickness than critical AF thickness (d{sub}(AF)>d{sub}c), which has been analyzed by using the single spin model under the condition of uniaxial anisotropy and unidirectional exchange coupling[1]. Recently, the angular dependence of the exchange bias (H{sub}(ex)) and coercive field (H{sub}c) has been explained by using Stoner-Wohlfarth (S-W) model[2-3]. The onset angle of coercivity measured with field angle has been defined as a critical angle. The magnetization reversal behavior has been transited from reversible to irreversible at the critical angle, which was analyzed at d{sub}(AF)>d{sub}c[4]. In this work, we measured the H{sub}(ex) and H{sub}c with field angle in the conditions of d{sub}(AF)>d{sub}c and d{sub}(AF)