3:30 PM - U2.07 Topological Nature of Magnetic Vortices in Patterned Mesoscopic Disks
Functional magnetic materials have garnered interest due to the potential applications in the emerging field of spintronics. More specifically magnetic vortices have been widely studied due to the quasi-particle/topological nature and are described as having two degrees of freedom, polarity and chirality. While there has been several studies exploring the fascinating behavior of vortices under perturbations using electrical measurements, scanning probe microscopy, and synchrotron based x-ray techniques, transmission electron microscopy provides unparalleled high resolution magnetic and structural information. This allows for a detailed analysis on how the local structure of different materials affects the translation motion of a vortex core under perturbation. Here, we present a direct imaging study of magnetically soft and hard mesoscopic discs of Permalloy and Cobalt under external field perturbations from equilibrium through annihilation and nucleation. The high resolution magnetic imaging of sub 6nm in Lorentz mode affords detail below critical domain wall features of less than 20nm where the soliton-regime breaks down into transverse Bloch walls far from equilibrium. By holding the ferromagnetic system in an external field we can capture the magnetic configuration far from equilibrium states near annihilation and during the nucleation process. Integrating these experiment with micromagnetic simulations we will describe how differently magnetic vortices can behave under perturbations, which is important when attempting to use them in applications such as logic, memories, and antennas.
Work supported by the DOE-BES-MSE,under Contract number DE-AC02-98CH10886 .
