The effect of the antiferromagnetic spin flop on exchange bias has been investigated in antiferromagnetic $\left({\mathrm{MnF}}_2\right)$–ferromagnetic (Fe) bilayers. Cooling and measuring in fields larger than the antiferromagnetic spin-flop field, $H_{\mathrm{SF}},$ causes an irreversible reduction of the magnitude of the exchange bias field, $H_E.$ This indicates that, contrary to what is normally assumed, the interface spin structure does not remain “frozen in” below $T_N$ if large enough fields are applied.

• Received 20 September 1999

DOI:https://doi.org/10.1103/PhysRevB.61.R6455