  We study the magnetic properties of cylindrical ferromagnetic core -
antiferromagnetic shell nanowires using Monte Carlo simulations and a classical
Heisenberg Hamiltonian in order to elucidate the impact of the oxidized shell
on the magnetic properties and the magnetization reversal mechanism. We find
that the coupling to the antiferromagnetic shell leads to suppression of the
coercivity and emergence of a weak exchange bias effect. Comparison of the
magnetization reversal mechanism in the bare and the surface-oxidized nanowire
reveals that the domain wall propagation and annihilation remains the dominant
reversal mechanism in surface oxidized nanowires as in their ferromagnetic
counterparts. However, the interface exchange coupling introduces a secondary
reversal mechanism activated in the central part of the wire with
characteristics of coherent rotation, which acts in synergy to wall propagation
leading to enhancement of the wall mobility. This effect is more pronounced in
nanowires with large exchange bias values and is attributed to the
uncompensated interface moments that act as nucleation centers for
magnetization reversal. Our results are in good agreement with recent
measurements in Co and Co/CoO nanowires.
