Origin of the Angular Dependent Magnetization Reversal Processes in Exchange-Biased Bilayers

A modified Metropolis Monte Carlo method, which exactly considers the influences of energy barriers on every spin reversal, is employed to simulate the angular dependence of magnetization reversal processes in the epitaxial ferromagnetic/antiferromagnetic bilayers which are not subjected to field-cooling treatments and have different interfacial couplings. With the increase of interfacial coupling, exchange bias appears, increases, and becomes asymmetric about the direction of anisotropy axes. Coercivity is reduced and the mirror symmetry of its angular dependence is also broken. Finally, it becomes magnetic-history-related. The magnetization reversal mechanisms and the microscopic spin configurations during ferromagnetic magnetization reversals are explored to interpret the phenomena. Rotation of magnetic field established the coercivity behaviors, while the coercive fields at the increasing branch, the sizes of domains and walls, and the numbers of domain-wall nucleation sites are all dependent on the interfacial coupling. Our numerical findings open new paths for the tailoring of exchange-biased bilayers.