Tunable room temperature magnetic skyrmions in centrosymmetric kagome magnet Mn$_4$Ga$_2$Sn
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.