Impact of magnetization easy-axis distributions on the ferromagnet-antiferromagnet exchange-coupling estimation

It is frequently reported that different measurement techniques may yield distinct values for the exchange anisotropy, being the difference of up to one order of magnitude on comparing magnetization loop with ac susceptibility measurements. We show, by both model calculations and a straight-forward experiment, that at least part of this difference could be attributed to big errors in the evaluation of the ferromagnet/antiferromagnet exchange coupling strengths obtained by means of ac magnetic susceptibility and dc magnetometry measurements which are caused by neglecting the easy-axis distributions or underestimating the uniaxial anisotropy of the ferromagnetic material.