We use spin-torque resonance to probe simultaneously and separately thedynamics of a magnetic domain wall and of magnetic domains in a nanostripemagnetic tunnel junction. Thanks to the large associated resistance variationswe are able to analyze quantitatively the resonant properties of these singlenanoscale magnetic objects. In particular, we find that the magnetic damping ofboth domains and domain walls is doubled compared to the damping value of theirhost magnetic layer. We estimate the contributions to damping arising fromdipolar couplings between the different layers in the junction and from theintralayer spin pumping effect. We find that they cannot explain the largedamping enhancement that we observe. We conclude that the measured increaseddamping is intrinsic to large amplitudes excitations of spatially localizedmodes or solitons such as vibrating or propagating domain walls
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