Correlation between the exchange bias and the degree of ordering of antiferromagnetic layer in PtMn/Co–Fe bilayers

Abstract Correlation between the unidirectional anisotropy constant, JK, and the degree of ordering of PtMn layer was investigated for Pt55Mn45/Co90Fe10 bilayer, as a function of the annealing time and the PtMn layer thickness, dAF. As a result, we found the linear relations between JK and the degree of ordering, f FCT · S , in the cases of the bilayers with dAF=5–50 nm. From the extrapolation of the linear relations to f FCT · S =1 , meaning the perfect ordering of PtMn layer, we obtained the attainable value of JK and the intrinsic critical thickness of the PtMn layer to be 0.26 erg/cm2 and 6 nm, respectively.