  The successful realization of skyrmion-based spintronic devices depends on
the easy manipulation of underlying magnetic interactions in the
skyrmion-hosting materials. Although the mechanism of skyrmion formation in
non-centrosymmetric magnets is comprehensively established, the stabilization
process of different skyrmion-like magnetic textures in centrosymmetric magnets
needs further investigation. Here, we utilize Lorentz transmission electron
microscopy study to report the finding of a tunable skyrmion lattice up to room
temperature in a centrosymmetric kagome ferromagnet Mn$_4$Ga$_2$Sn. We
demonstrate that a controlled switching between the topological skyrmions and
non-topological type-II magnetic bubbles can be realized at the optimal
magnetic anisotropy. We find that the topological skyrmions are the
energetically most stable magnetic objects in the centrosymmetric hexagonal
magnets, whereas application of in-plane magnetic field stabilizes type-II
magnetic bubbles as an excited state. The present study is a significant step
towards understanding of the skyrmion stabilization mechanism in
centrosymmetric materials for their future applications.
