Ferromagnetic resonance of individual magnetic double layer microwires

Ferromagnetic resonance measurements were done on individual magnetic double layer microwires. Two magnetic precession modes, namely, the acoustic (in-phase) and the optical (out-of-phase) modes, were clearly revealed. Their frequency dependencies on applied magnetic field were measured, fitted with simple theoretical predictions, and explained in the context of interlayer magnetostatic dipolar coupling. The effectiveness of exciting the two precession modes by injected microwave electric current was studied against different layer dimensions. The results are highly relevant to fast switching of small magnetic devices relying on Amperian field generated by in-plane current inside the devices.