Exchange bias in Fe/Ir20Mn80 bilayers: Role of spin-glass like interface and 'bulk' antiferromagnet spins

We have performed magnetic measurements such as temperature (T), cooling field (mu 0H(FC)) dependence and training effect of exchange bias (EB) to investigate the magnetic nature of the interface in the Fe/Ir20Mn80 system. Bilayers of different thicknesses of Ir20Mn80 (antiferromagnetic) have been prepared by dc magnetron sputtering at room temperature. The variation of exchange bias field (mu H-0(EB)) with Ir20Mn80 thickness indicates that the 'bulk' spins of the antiferromagnet contribute to EB. Exponential decay of mu H-0(EB) and coercive field (mu H-0(C)) with T reveals the possible presence of a spin glass (SG) like interface. The decrease of mu H-0(EB) with increasing ktoHFc provides further evidence of SG like behaviour at the interface. The results of training effect data indicate the presence of frozen and rotatable spins at the magnetically frustrated interface of these Fe/Ir20Mn80 bilayers.