High exchange-bias blocking temperature in an ultrathin amorphous antiferromagnet system

We experimentally observed an ultrahigh blocking temperature, above 600 K, in an exchange-biased Fe/FeO bilayer after field annealing at 773 K. This is far above the 198 K N\'eel temperature of bulk FeO. By comparing with an Fe/FeO/Fe trilayer and studying the Fe thickness dependence, we find that the magnetic proximity effect, due to coupling between the Fe layer and the ultrathin amorphous FeO layer, is responsible for the high blocking temperature. The realization of high-temperature exchange bias using an ultrathin antiferromagnet paves the way to further miniaturize magnetic devices for high-information-density applications.