Hongki Min1,2, Robert D. McMichael1, Jacques Miltat1,2,3, Michael J. Donahue4 and Mark D. Stiles1

 1 Center for Nanoscale Science and Technology, NIST, Gaithersburg, MD 20899
2 Maryland NanoCenter, University of Maryland, College Park, MD 20742
3Laboratoire de Physique des Solides Université Paris XI Orsay,
Bâtiment 510, 91405 ORSAY CEDEX, France
4Mathematical and Computational Sciences Division, NIST, Gaithersburg, MD 20899-8910


The dynamics of magnetic domain walls driven by fields or currents is important to possible schemes for nanoscale magnetic memory devices.  Experimental measurements of domain wall propagation are typically interpreted by comparison to ideal models that ignore the effects of extrinsic disorder and the internal dynamics of domain wall structures.  To understand the effect of disorder and internal dynamics, we perform micromagnetic simulations in the presence of an extrinsic random disorder and analyze the results using the effective models frequently used to interpret experiments.  We study the dynamics of vortex wall propagation driven by fields or currents, and vortex gyration driven by an external magnetic field pulse. We find that the results can be understood in terms of an effective damping that increases with the disorder.