  We investigate the influence of the domain wall ferromagnetic resonance
frequency on the spin transfer torque in a ferromagnetic nanowire. By employing
micromagnetic simulations with the spin transfer torque, we find that the
domain wall resonance frequency decreases with increasing spin polarized
current density, when there is no change in the resonance frequency of the
domain itself. Surprisingly, the variation of the resonance frequency is
remarkable (> 1.6 GHz) with the spin transfer torque even though the domain
wall is pinned. Since the presented domain wall ferromagnetic resonance study
has been performed for the pinned domain wall, the contributions of extrinsic
defects are excluded. It is strong advantages of the present study, since the
effects of extrinsic pinning sites are inevitable in the imaging or transport
measurements.
