Bifurcation diagram and large energy dissipation caused by chaotic domain-wall motion

The chaotic oscillation of a domain wall is investigated by computer simulation. The bifurcation diagrams of the wall velocity and the power spectrum are calculated as a function of the amplitude of the external magnetic field. The Feigenbaum scenario of the period doubling bifurcations is found to be one of the routes to chaos in this system. The power spectrum has a continuous distribution, which is evidence of chaotic motion. The energy loss caused by the domain-wall motion is calculated by integrating the damping term. The value of the energy loss is discussed in connection with the bifurcation diagram. The energy loss jumps to a high value at the first transition to chaos. The energy loss in the periodic window is larger than the value in the neighboring chaotic region in spite of their having the same damping coefficient