Effects of component ratio and easy axes distribution on the exchange bias in ferromagnetic–antiferromagnetic random alloys

For a ferromagnetic (FM)–antiferromagnetic (AFM) system with composition (FM)x+(AFM)1−x(FM)x+(AFM)1−x, a modified Monte Carlo Metropolis method is performed to study the effects of x and easy axes distribution at the FM/AFM nearest neighbors on exchange bias field HE, coercivity HC, and vertical magnetization shift ME after cooling under different magnetic fields hCF. When the orientations of easy axes are uniform, the x dependence of HE and ME undergo a non-monotonous to monotonous process with the increase of hCF, whereas HC shows a more complex behavior. On the other hand, for the case of the random orientation, HC has a peak around x=0.5x=0.5, while ME decreases with the increase of x. HE exhibits negative extrema at small x and disappears for larger x. However, abnormal positive HE observed depends on the frustration and the distinct trends of two coercive fields with x in such a special model.