Element Specific Observation of Ferromagnetic Interlayer Exchange Coupled Dual Vortex Core Nano Systems

We report on the magnetic evolution of magnetic vortices in nanoscale and multilayer disk structures. ~The tri-layer structure consists of Co and Permalloy (Py) layers, coupled across a thin (1nm) Cu spacer that provides strong coupling between the Co and Py layers. ~Element-resolved full-field XMCD microscopy is combined with ultra-high resolution Lorentz transmission electron microscopy, permitting measurement of both layer-resolved domain patterns and the vortex structure averaged across the tri-layer. ~We examine the evolution of the vortex structure while the nanostructure is cycled through the M-H hysteresis loop. ~In particular we will discuss the effects of strong interlayer exchanged coupling on a dual vortex core system, including analysis of the layer-resolved coercivity, and the evolution, deformation, annihilation, and nucleation of the vortices.