Tuning the exchange bias in large area Co/CoO nanowire arrays

The exchange bias effect in Co (25 nm)/Co (5 nm)/Cu (2 nm) nanowire arrays has been systematically investigated. The exchange bias field H(E) is strongly dependent on the orientation of field cooling relative to the easy axis of the nanowires. We have exploited the competition between field cooling induced unidirectional anisotropy and shape anisotropy of the nanowires to tune both the direction and magnitude of exchange bias. A strong interplay between thermal activation effects and CoO domain size confinement in the nanowires also results in H(E) for the nanowire arrays being either smaller or larger than the continuous film. (C) 2010 American Institute of Physics. [doi:10.1063/1.3340455]