SEMINAR: Physics Seminar

Magnetic domain patterns form in perpendicularly-magnetized ultrathin films due to the combination of short-range attractive magnetic exchange interactions and long-range repulsive magnetic dipolar interactions. The dynamics of these patterns, and the domains within them, are described by the complicated interplay of different relaxation processes that act across many orders of magnitude in temporal and spatial length. Our recent measurements of Fe/ 2 ML Ni/W(110) films have permitted the quantitative separation and characterization of these times scales through measurements of the ac magnetic susceptibility. The processes include the motion of existing domain walls, the creation and annihilation of domain walls, and the transformation between domain wall patterns. The temporal analysis of this hierarchy complements an extensive literature that uses microscopy to characterize the domains spatially.