Abstract

Chiral magnetic skyrmions1,2 are nanoscale vortex-like spin textures that form in the presence of an applied magnetic field in ferromagnets that support the Dzyaloshinskii–Moriya interaction (DMI) because of strong spin–orbit coupling and broken inversion symmetry of the crystal3,4. In sharp contrast to other systems5,6 that allow for the formation of a variety of two-dimensional (2D) skyrmions, in chiral magnets the presence of the DMI commonly prevents the stability and coexistence of topological excitations of different types7. Recently, a new type of localized particle-like object—the chiral bobber (ChB)—was predicted theoretically in such materials8. However, its existence has not yet been verified experimentally. Here, we report the direct observation of ChBs in thin films of B20-type FeGe by means of quantitative off-axis electron holography (EH). We identify the part of the temperature–magnetic field phase diagram in which ChBs exist and distinguish two mechanisms for their nucleation. Furthermore, we show that ChBs are able to coexist with skyrmions over a wide range of parameters, which suggests their possible practical applications in novel magnetic solid-state memory devices, in which a stream of binary data bits can be encoded by a sequence of skyrmions and bobbers.

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Acknowledgements

This work was supported by the National Key R&D Program of China, grant no. 2017YFA0303201, the Natural Science Foundation of China, grant nos 51622105 and 11474290, the Key Research Program of Frontier Sciences, CAS, grant no. QYZDB-SSW-SLH009, the Key Research Program of the Chinese Academy of Science, grant no. KJZD-SW-M01, the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology, grant no. 2016FXCX001 and the Youth Innovation Promotion Association CAS no. 2015267. F.Z. and R.E.D.-B. acknowledge the European Union for funding through the Marie Curie Initial Training Network SIMDALEE2. The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programmer (FP7/2007–2013)/ERC grant agreement no. 320832. The work of F.N.R. was supported by the Swedish Research Council grant no. 642-2013-7837. The work of A.B.B. was carried out within the state assignment of FASO of Russia (theme Quantum no. 01201463332).

Author information

Affiliations

  1. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany

    • Fengshan Zheng
    • , Jan Caron
    • , András Kovács
    •  & Rafal E. Dunin-Borkowski
  2. Department of Physics, KTH-Royal Institute of Technology, Stockholm, Sweden

    • Filipp N. Rybakov
  3. M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia

    • Filipp N. Rybakov
    •  & Aleksandr B. Borisov
  4. Ural Federal University, Ekaterinburg, Russia

    • Filipp N. Rybakov
    •  & Aleksandr B. Borisov
  5. National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Tsinghua University, Beijing, China

    • Dongsheng Song
  6. The Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and University of Science and Technology of China, Chinese Academy of Science (CAS), Hefei, Anhui Province, China

    • Shasha Wang
    • , Haifeng Du
    • , Mingliang Tian
    •  & Yuheng Zhang
  7. Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Jiangsu Province, China

    • Shasha Wang
    • , Haifeng Du
    • , Mingliang Tian
    •  & Yuheng Zhang
  8. Institute of Physics, Chinese Academy of Sciences, Beijing, China

    • Zi-An Li
  9. Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany

    • Nikolai S. Kiselev
    •  & Stefan Blügel

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Contributions

N.S.K. and H.D. contributed to the planning of this study. F.N.R. proposed the concept and, together with A.B.B., performed the preliminary simulations. F.Z. together with D.S., S.W., N.S.K. and H.D. performed the experiments. H.D., A.K. and R.E.D.-B. supervised and designed the experiments. N.S.K. performed the micromagnetic simulations and prepared the initial version of the manuscript. J.C. calculated the theoretical phase-shift images. F.N.R., M.T., S.B. and R.E.D.-B. edited the manuscript. All of the authors discussed the results and contributed to the preparation of the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding authors

Correspondence to Haifeng Du or Nikolai S. Kiselev.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–11, Supplementary Table 1, Supplementary references.

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DOI

https://doi.org/10.1038/s41565-018-0093-3