The influence of finite size and shape anisotropy on exchange bias : a study of patterned Co/CoO nanostructures

The influence of finite dimensions on the exchange bias effect in patterned polycrystalline Co/CoO ferromagnet/antiferromagnet exchange bias systems was studied. Magnetization measurements on the smallest structures reveal that the exchange bias shift increases as the structure size becomes smaller. Off-specular neutron scattering experiments were used to study the asymmetric magnetization reversal behaviour.NRC publication: N

Magnetization reversal in exchange biased Co/CoO patterns

The influence of patterning on exchange bias has been investigated using arrays of micron-sized Co/CoO dots with different lateral confinement and length-to-width ratio. The patterned samples show higher coercive and exchange bias fields than a continuous Co/CoO bilayer. As in unpatterned film, magnetization reversal mechanisms on opposite sides of the hysteresis loops of the microstructured samples are different. However, with the increase of lateral confinement and shape anisotropy of the dots, the asymmetry in the magnetization reversal starts to differ from that observed in continuous Co/CoO films. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005

Magnetization and polarized neutron reflectivity experiments on patterned exchange bias structures

Patterned Co/CoO thin film structures have been investigated by magnetization and polarized neutron reflectivity measurements in order to study the influence of finite size and shape anisotropy effects on the magnetization reversal. An anomaly was found in the upper branch of the hysteresis loops, probably caused by incomplete bias in the patterned structures. The asymmetry in magnetization reversal mechanism commonly found in the two branches of the hysteresis loops of unpatterned Co/CoO layers is altered in the patterned structures, consistent with the existence of interfacial domains. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005