Coercivity and random interfacial exchange coupling in CoPt/Co films
  Hard-soft bilayers are analogous to prototype exchange-biased ferromagnetic -antiferromagnetic systems as the minor loop of the soft layer is biased by the hard and furthermore they offer bias layer tunability. In sputtered CoPt/Co hard-soft bilayers we demonstrate that the exchange bias field shows a linear dependence on the hard layer magnetization, while the coercivity shows a quadratic dependence. Analysis of the minor hysteresis loop features supported by Monte-Carlo simulations provide clear evidence that the coercivity of the soft layer is mainly determined by the tunable randomness of the domain state of the hard layer. 
V. Alexandrakis, D. Kechrakos, N. Moutis, D. Niarchos, G. Hadjipanayis   and I. Panagiotopoulos
cond-mat.mtrl-sci