Asymmetry of the remagnetization processes in exchange-biased NiFe NiO bilayers

The magnetization reversal of NiFe/NiO exchange-coupled films with direct ( NiFe/NiO) and inverse (NiO/NiFe) deposition ordering of the ferro- and anti ferromagnetic layers onto the MgO substrate were investigated by means of t he magneto-optical indicator film technique and vibrating sample magnetomet ry. Processes of thr domain formation and growth as well as the magnitude o f the macroscopic coercive force were found to depend drastically on the gr owth order. oreover all of our bilayers were characterized by an asymmetry in the activity of crystal lattice defects as domain wall nucleation center s. The results are discussed in terms of variations in the real crystal str ucture of the antiferromagnetic layer. (C) 1999 Elsevier Science B.V. All r ights reserved.