Spin wave excitations in exchange biased IrMn/CoFe bilayers

TL;DR

This study uses atomistic simulations to analyze how spin waves are injected and propagate in exchange-biased IrMn/CoFe bilayers, revealing complex behaviors and limitations for magnetic switching.

Contribution

It demonstrates that spin waves can be efficiently injected into non-collinear antiferromagnetic IrMn, highlighting the impact of excitation frequency and amplitude on spin wave behavior.

Findings

Spin waves exhibit complex beating due to non-collinear order.

Frequency response depends on excitation parameters.

Spin wave strength decays with distance from interface.

Abstract

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.