Direct Observation of Chiral Bobbers in Nanostructured FeGe

Chiral magnets represent a special class of magnetically ordered crystals that are characterized by broken inversion symmetry and strong spin-orbit coupling, giving rise to the Dzyaloshinskii-Moriya interaction (DMI). The presence of the DMI usually prevents the stability and coexistence of topological excitations of different types. However, recently a new type of localized particle-like object -- the chiral bobber (ChB) - was predicted theoretically in such materials¹. Such hybrid particle-like states are composed of continuum magnetization vector fields and singularities that are known as Bloch points. Here, we report the experimental observation of ChBs in thin films of B20-type FeGe by means of quantitative off-axis electron holography², which allowed us to identify the part of the temperature-field magnetic phase diagram, in which ChBs exist and to identify two distinct mechanisms for their nucleation. We show that ChBs are able to coexist with skyrmions over a wide range of parameters, suggesting their possible practical application in novel magnetic solid state memory devices, in which a stream of binary data bits can be encoded by a sequence of skyrmions and bobbers².
[1] F. N. Rybakov et al. Phys. Rev. Lett. 115, 117201 (2015).
[2] F. Zheng et al. arXiv:1706.04654