Ferromagnetic resonance study of dual exchange bias field behavior in NiFe/IrMn/Co trilayers

Magnetometry study of magnetron sputtered NiFe/IrMn/Co trilayers reveal that the exchange bias field at the NiFe/IrMn interface decreases with increasing NiFe layer thickness, up to 150 angstrom. At the IrMn/Co interface, a decrease also occurs when the NiFe layer thickness increases. Ferromagnetic resonance measurements at X and Q-band frequencies reveal that the same dependence at both interfaces, up to a 70 angstrom thick NiFe, is due to a spiraling interlayer coupling between the NiFe and Co layers. Unexpected increase with thicker NiFe layer is due to domain walls at the NiFe/IrMn interface in the presence of low static magnetic fields. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4791574]