Thickness dependence of oscillatory exchange bias

We observed oscillatory exchange bias with temperature for various Fe/Gd multilayers. Exchange bias was observed to oscillate between positive and negative fields. It is found that the oscillatory pattern is strongly affected by the underlayer Gd thickness and the number of the bilayer repetitions. The position of the 16nm thick Gd layer is crucial and if it is not in the right position the oscillations vanish. Coercive field is also oscillating within itself for the same temperature range studied. We speculate that oscillatory exchange bias is related to the underlying magnetic phase diagram of the ferrimagnetic multilayer.