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  • Low-Field Bi-Skyrmion Forma...
    Takagi, R; Yu, X Z; White, J S; Shibata, K; Kaneko, Y; Tatara, G; Rønnow, H M; Tokura, Y; Seki, S

    Physical review letters, 01/2018, Letnik: 120, Številka: 3
    Journal Article

    The real-space spin texture and the relevant magnetic parameters were investigated for an easy-axis noncentrosymmetric ferromagnet Cr_{11}Ge_{19} with Nowotny chimney ladder structure. Using Lorentz transmission electron microscopy, we report the formation of bi-Skyrmions, i.e., pairs of spin vortices with opposite magnetic helicities. The quantitative evaluation of the magnetocrystalline anisotropy and Dzyaloshinskii-Moriya interaction (DMI) proves that the magnetic dipolar interaction plays a more important role than the DMI on the observed bi-Skyrmion formation. Notably, the critical magnetic field value required for the formation of bi-Skyrmions turned out to be extremely small in this system, which is ascribed to strong easy-axis anisotropy associated with the characteristic helix crystal structure. The family of Nowotny chimney ladder compounds may offer a unique material platform where two distinctive Skyrmion formation mechanisms favoring different topological spin textures can become simultaneously active.