Domain Wall Nucleation in Epitaxial Exchange-Biased Fe/IrMn Bilayers with Highly Misaligned Anisotropies

The angular dependence of the magnetization reversal in epitaxial Fe/IrMn bilayers with collinear and noncollinear cubic and unidirectional anisotropies is investigated. Multistep loops with different magnetization reversal processes are observed for either positive or negative angles with respect to the Fe easy axis. The angular dependence of the switching fields displays the broken symmetry of the induced non-collinearity. The experimental results are reproduced with a generalized domain wall nucleation model that includes the induced anisotropy configuration and the peculiar asymmetric magnetic switching behavior. These results highlight the importance of the relative angle between anisotropies in epitaxial exchange bias systems with incoherent rotation reversal mechanism, opening a new pathway for tailoring the magnetic properties of such systems.