Imaging of magnetization dynamics in artificial ferromagnetic nanoscale structures

We report time-resolved x-ray photoemission electron microscopy studies of the non-linear magnetization dynamics in artificial permalloy structures. Using pump-probe X-PEEM imaging to obtain a time resolution of ~100ps, we map out the response of a vortex state to a strong in-plane bias field of 5mT. We find that the initial formation of the vortex state is characterized by a complex transient domain state that includes a cross-tie domain wall. This state has implications for the subsequent formation and motion of the vortex core.