Magnetization reversal of the ferromagnetic layer in IrMn/CoFe bilayers

The magnetization reversal of the ferromagnetic layer in Ir/CoFe exchange-coupled bilayer films with different antiferromagnetic (AFM) layer thickness was investigated. Thermally activated reversal of the antiferromagnetic layer with a large time constant resulted in an increasing shift of the entire hysteresis loop towards zero field with increased period of time spent at negative saturation. The energy barriers for thermally activated reversal of the antiferroamgnetic layer decreased so the changes in the antiferromagnetic layer became more significant.