Effects of Antiferromagnetic Spin Rotation on Anisotropy of Ferromagnetic/Antiferromagnetic Bilayers

摘要

In epitaxial (111) oriented Ni$_{80}$Fe$_{20}$/Fe$_{50}$Mn$_{50}$ bilayers,we separate two distinct behaviors: unidirectional anisotropy (exchange bias)in thick Fe$_{50}$Mn$_{50}$, and enhanced coercivity in thinFe$_{50}$Mn$_{50}$. By measuring the magnetization response to a rotatingmagnetic field, we quantitatively determine the relevant anisotropies, anddemonstrate that the enhanced coercivity is related to the rotatable magneticanisotropy of Fe$_{50}$Mn$_{50}$. We also demonstrate the consequences of theanisotropy changes with temperature.