Exchange bias of antiferromagnets with random anisotropies and perfectly compensated interfaces

An alternative mechanism for exchange bias for ferromagnet/antiferromagnet bilayers with completely compensated interfaces is proposed and analyzed within the biquadratic coupling model. We show that a distribution of anisotropies in the antiferromagnet can lead to the appearance of exchange bias in a bilayer with a perfectly compensated interface without defects. The energy associated with the unidirectional anisotropy that gives rise to the shifted hysteresis curve is stored in antiferromagnetic domain walls between regions in the antiferromagnet with different anisotropy. This mechanism also leads naturally to an enhanced coercivity of the ferromagnet which is caused by the anisotropy in the antiferromagnet. (C) 2004 American Institute of Physics.