The effect of the antiferromagnetic spin flop on exchange bias has been inv
estigated in antiferromagnetic (MnF2)-ferromagnetic (Fe) bilayers. Cooling
and measuring in fields larger than the antiferromagnetic spin flop field,
H-SF, causes an irreversible reduction of the magnitude of the exchange bia
s field, HE. This indicates that, contrary to what is normally assumed, the
interface spin structure does not remain "frozen in" below T-N if large en
ough fields are applied.