Fabrication of magnetic ring structures for Lorentz electron microscopy

We have fabricated three-quarter ring structures on silicon nitride membranes for magnetic domain imaging using Lorentz electron microscopy. The ring structures have linewidths of 100, 250, 350 and 700 nm, and outer diameters of 1.65 μm. Using the Foucault imaging mode, we have observed the magnetic domain configurations in ring structures with an inter-ring separation of 100 nm. Head-to-head transverse domain walls and vortices are seen depending on the ring geometry and stray field interactions between the rings. It is also possible to see contrast due to the stray field produced by transverse walls.