Influence of antiferromagnetic interlayer on the exchange coupling of FM1/AFM/FM2 multilayers

The effect of spin configuration of ferromagnetic (FM1)/antiferromagnetic (AFM) bilayer on the exchange bias of AFM/FM2 bilayer has been investigated in series of designed FM1/AFM/FM2 trilayers. Field cooling of the magnetic sandwich layers, with parallel or antiparallel alignment of the two FM layers, lead to a different interfacial spin configuration and internal AFM domain state. Minor magnetic hysteresis loops show that when the AFM layer is thin enough, the exchange-bias effect after field cooling with parallel and anti-parallel spin configuration is different. When the AFM layer is thick enough, it is difficult to observe the interaction between the spin configuration of FM1/AFM bilayer and the exchange-bias effect of AFM/FM2 bilayer. The AFM layer-thickness dependence on the exchange interaction of other FM layers, mediated by the AFM layer, can be interpreted by the domain state model.