Observation of hybrid magnetic skyrmion bubbles in Fe3Sn2 nanodisks

It is well known that there are two types of magnetic bubbles in uniaxial magnets. Here, using Lorentztransmission electronic microscopy magnetic imaging, we report the direct experimental observation of three-dimensional (3D) type-III hybrid bubbles, which comprise Neel-twisted skyrmion bubbles with topological charge Q = -1 in near-surface layers and type-II bubbles with Q = 0 in interior layers, in Fe3Sn2 nanodisks. Using the tilted magnetic field, we further show the controlled topological magnetic transformations of three types of bubbles in a confined ferromagnetic nanodisk. Our observations are well reproduced using micromagnetic simulations based on measured magnetic parameters. Our results advance fundamental classification and understanding of magnetic bubbles, which could propel the applications of 3D magnetism.

Automated summary

Using Lorentz transmission electronic microscopy magnetic imaging, we directly observed three-dimensional (3D) type-III hybrid bubbles in Fe3Sn2 nanodisks, which consist of Neel-twisted skyrmion bubbles with topological charge Q = -1 in near-surface layers and type-II bubbles with Q = 0 in interior layers. By applying a tilted magnetic field, we demonstrated controlled topological magnetic transformations of the three types of bubbles in a confined ferromagnetic nanodisk. Our observations were well reproduced with micromagnetic simulations based on measured magnetic parameters. This study advances the fundamental classification and understanding of magnetic bubbles, with potential implications for applications of 3D magnetism.