  Using an atomistic spin model, we have simulated spin wave injection and
propagation into antiferromagnetic IrMn from an exchange coupled CoFe layer.
The spectral characteristics of the exited spin waves have a complex beating
behavior arising from the non-collinear nature of the antiferromagnetic order.
We find that the frequency response of the system depends strongly on the
strength and frequency of oscillating field excitations. We also find that the
strength of excited spin waves strongly decays away from the interfacial layer
with a frequency dependent attenuation. Our findings suggest that spin waves
generated by coupled ferromagnets are too weak to reverse IrMn in their
entirety even with resonant excitation of a coupled ferromagnet. However,
efficient spin wave injection into the antiferromagnet is possible due to the
non-collinear nature of the IrMn spin ordering.
