The complementary nature of coercivity enhancement and exchange bias in a general ferro-antiferromagnet exchange coupled system

Complementary nature of coercivity enhancement and exchange bias in a ferro-antiferromagnet (F-AF) exchange coupled system with arbitrary configuration refers to the relation Hsw0−=Ms∕χin,max, with Ms being the saturation magnetization of the F part, Hsw0− being the field at which the F magnetization starts to be unstable, applied opposite to the stable direction of the F magnetization in the absence of external field, and χin,max being the maximal initial susceptibility, for which the field is applied perpendicular to that stable direction. This relation is a special case of a more general result for a single domain particle, proved in this paper. In a F-AF system, when the F magnetization behaves coherently, the effect of F-AF coupling can be absorbed into the anisotropy of the F part and the system can be treated as a single domain in an external field.