  The discovery of magnetic skyrmion bubbles in centrosymmetric magnets has
been receiving increasing interest from the research community, due to the
fascinating physics of topological spin textures and its possible applications
to spintronics. However, key challenges remain, such as how to manipulate the
nucleation of skyrmion bubbles to exclude the trivial bubbles or metastable
skyrmion bubbles that usually coexist with skyrmion bubbles in the
centrosymmetric magnets. Here, we report having successfully performed this
task by applying spatially geometric confinement to a centrosymmetric
frustrated Fe3Sn2 magnet. We demonstrate that the spatially geometric
confinement can indeed stabilize the skyrmion bubbles, by effectively
suppressing the formation of trivial bubbles and metastable skyrmion bubbles.
We also show that the critical magnetic field for the nucleation of the
skyrmion bubbles in the confined Fe3Sn2 nanostripes is drastically less, by an
order of magnitude, than that what is required in the thin plate without
geometrical confinement. By analyzing how the width and thickness of the
nanostripes affect the spin textures of skyrmion bubbles, we infer that the
topological transition of skyrmion bubbles is closely related to the
dipole-dipole interaction, which we find is consistent with theoretical
simulations. The results presented here represent an important step forward in
manipulating the topological spin textures of skyrmion bubbles, making us
closer to achieving the fabrication of skyrmion-based racetrack memory devices.
