Tuning exchange bias effects by ion-beam bombardment in NiFe/NiO bilayers

We have studied the correlation between the ion-beam bombardment and exchange bias effects in NiFe/NiO bilayers. The dependence of the exchange bias field, H
_ex
, with increasing V
_EH
suggests strongly that the Ar ion-beam bombardment process may increase the spin misalignment in FM/AF interfaces (resulting in a decrease of H
_ex
) or create uncompensated NiO spins (shown by a shift from negative to positive H
_ex
), depending on the energy used. The polarity switch from -H
_ex
to +H
_ex
occurred with increasing ion-beam bombardment time (t
_bom.
> 5 mins).