  Skyrmion-containing devices have been proposed as a promising solution for
low energy data storage. These devices include racetrack or logic structures
and require skyrmions to be confined in regions with dimensions comparable to
the size of a single skyrmion. Here we examine Bloch skyrmions in FeGe device
shapes using Lorentz transmission electron microscopy (LTEM) to reveal the
consequences of skyrmion confinement in a device-like structure.
Dumbbell-shaped elements were created by focused ion beam (FIB) milling to
provide regions where single skyrmions are confined adjacent to areas
containing a skyrmion lattice. Simple block shapes of equivalent dimensions
were also prepared to allow a direct comparison with skyrmion formation in a
less complex, yet still confined, device geometry. The impact of applying a
magnetic field and varying the temperature on the formation of skyrmions within
the shapes was examined. This revealed that it is not just confinement within a
small device structure that controls the position and number of skyrmions, but
that a complex device geometry changes the skyrmion behaviour, including
allowing skyrmions to form at lower applied magnetic fields than in simple
shapes. This could allow methods to be developed to control both the position
and number of skyrmions within device structures.
