Exchange bias in the IrMn/Co structures with alternative sequences of antiferromagnetic and ferromagnetic layers

The magnetic properties of Mo/IrMn/Co/Mo/SiO₂/Si structures with alternative sequences of the antiferromagnetic and ferromagnetic layers have been studied by measuring the angular dependence of the high-frequency radiation absorption in the ferromagnetic resonance region. The layers have been prepared by pulsed laser deposition in the absence of a magnetic field. It has been found that thermal annealing and cooling make it possible to create the exchange bias in the structure with the upper antiferromagnetic layer at a temperature much below the Néel temperature. At the same time, the identical heat treatment does not induce the exchange bias in the structure with the upper ferromagnetic layer. The possible mechanisms of the phenomena observed are discussed.