  The motions of domain walls driven by magnetic field in soft magnetic
nanostripes were calculated. The domain walls reveal steady motions in the low
fields and oscillations of their internal structure above a critical field. A
developed soliton model of the walls explains its dynamics by the motions of a
limited number of magnetic topological solitons such as vortex and antivortex.
We predict the reduced wall velocity and critical field in the low-field
regime, and increased wall-oscillation frequency in nanostripes, compared to 1D
Walker solution for bulk magnets. The critical field and velocity are
determined by the nanostripe sizes, whereas the oscillation frequency depends
only on the field strength.

Pattern Formation and Solitons