Magnetic domain wall ferromagnetic resonance in ferromagnetic nanowires due to the spin transfer torque

The influence of the spin transfer torque on a domain wall is investigated by domain wall ferromagnetic resonance micromagnetic simulations. When current is applied to the pinned domain wall in a ferromagnetic nanowire, we find two resonance frequencies of the domain wall around 2 and 7 GHz. The lower peaks represent the vibration of the whole domain wall. The higher peaks are due to the resonance frequency of the spins inside the domain wall, which show remarkable (>1:6 GHz) shifts with the spin torque. Since no domain wall displacement is involved, we can exclude the effects of the unwanted extrinsic pinning sites.