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Near room-temperature formation of a skyrmion crystal in thin-films of the helimagnet FeGe

Nature Materials volume 10, pages 106–109 (2011)Cite this article

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Abstract

The skyrmion1,2,3,4, a vortex-like spin-swirling object, is anticipatedto play a vital role in quantum magneto-transport processes such as the quantum Hall and topological Hall effects3,5,6. The existence of the magnetic skyrmion crystal (SkX) state was recently verified experimentally for MnSi and Fe0.5Co0.5Si by means of small-angle neutron scattering7,8 and Lorentz transmission electron microscopy9. However, to enable the application of such a SkX for spintronic function, materials problems such as a low crystallization temperature and low stability of SkX have to be overcome. Here we report the formation of SkX close to room temperature in thin-films of the helimagnet FeGe. In addition to the magnetic twin structure, we found a magnetic chirality inversion of the SkX across lattice twin boundaries. Furthermore, for thin crystal plates with thicknesses much smaller than the SkX lattice constant (as) the two-dimensional SkX is quite stable over a wide range of temperatures and magnetic fields, whereas for quasi-three-dimensional films with thicknesses over as the SkX is relatively unstable and observed only around the helical transition temperature. The room-temperature stable SkX state as promised by this study will pave a new path to designing quantum-effect devices based on the controllable skyrmion dynamics.

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Figure 1: Magnetic twin structure and skyrmion lattice represented by the lateral magnetization distribution in a helimagnet FeGe.
Figure 2: External magnetic field and temperature dependence of the skyrmion lattice in FeGe.
Figure 3: The sample thickness dependence of the SkX phase diagram in the plane of magnetic field and temperature.

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Acknowledgements

We would like to thank N. Nagaosa, T. Arima, Y. Kaneko, Y. Taguchi, K. Ishizuka and T. Hara for helpful discussions. This work was partly supported by the Nanotechnology Network Project (No. ADE21005) and Grant-in-Aids for Scientific Research (No. 20340086, 20046004 and 22014003) from the Ministry of Education, Culture, Sports, Science and Technology of Japan, and also by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program).

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Authors and Affiliations

  1. Multiferroics Project, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Tokyo 113-8656, Japan

    X. Z. Yu, Y. Onose & Y. Tokura

  2. Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan

    N. Kanazawa, Y. Onose, S. Ishiwata & Y. Tokura

  3. Advanced Electron Microscopy Group and High Voltage Electron Microscopy Station, National Institute for Materials Science, Tsukuba 305-0044, Japan

    K. Kimoto, W. Z. Zhang & Y. Matsui

  4. Cross-Correlated Materials Research Group and Correlated Electron Research Group, RIKEN-ASI, Wako 351-0198, Japan

    Y. Tokura

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  1. X. Z. Yu
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Contributions

X.Z.Y. carried out the Lorentz TEM observations, performed the high-resolution spin texture in the skyrmion lattice and prepared the manuscript. N.K., Y.O. and S.I. prepared the polycrystalline sample and wrote part of the method and discussion sections. W.Z.Z. prepared the TEM sample. K.K. contributed to the EELS analyses. Y.M. contributed to the discussion and assisted in writing the discussions. Y.T. contributed to planning of the study and writing of the manuscript.

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Correspondence to X. Z. Yu or Y. Tokura.

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Yu, X., Kanazawa, N., Onose, Y. et al. Near room-temperature formation of a skyrmion crystal in thin-films of the helimagnet FeGe. Nature Mater 10, 106–109 (2011). https://doi.org/10.1038/nmat2916

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