Interaction in ferromagnetic thin film across an antiferromagnetic layer

NiFe (5 nm)/IrMn (15 nm)/NiFe (t nm) dual exchange bias systems with various thicknesses of top NiFe layers were grown in a magnetic field. Magnetometry studies revealed that the exchange bias field Hex at the bottom NiFe/IrMn interface of fixed thickness increased when the Hex at the top IrMn/NiFe interface increased. The bottom Hex increased linearly with the decrease in thickness of the top pinned layer. Furthermore, the Hex values achieved in the bottom NiFe/IrMn interface in the dual exchange bias samples were all larger than that of the same thickness of NiFe/IrMn bilayer. In addition, by comparison of NiFe/IrMn/NiFe and Cu/IrMn/NiFe with similar microstructures, Hex achieved in the top NiFe/IrMn interface was found to be large in the dual exchange bias system. These results provide evidence of the interaction in the dual exchange-coupling system across the antiferromagnetic layer.