Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Robust metastable skyrmions and their triangular–square lattice structural transition in a high-temperature chiral magnet

Nature Materials volume 15, pages 1237–1242 (2016)Cite this article

Subjects

Abstract

Skyrmions, topologically protected nanometric spin vortices, are being investigated extensively in various magnets1,2,3,4,5,6,7,8,9,10,11. Among them, many structurally chiral cubic magnets host the triangular-lattice skyrmion crystal (SkX) as the thermodynamic equilibrium state. However, this state exists only in a narrow temperature and magnetic-field region just below the magnetic transition temperature Tc, while a helical or conical magnetic state prevails at lower temperatures. Here we describe that for a room-temperature skyrmion material12, β-Mn-type Co8Zn8Mn4, a field-cooling via the equilibrium SkX state can suppress the transition to the helical or conical state, instead realizing robust metastable SkX states that survive over a very wide temperature and magnetic-field region. Furthermore, the lattice form of the metastable SkX is found to undergo reversible transitions between a conventional triangular lattice and a novel square lattice upon varying the temperature and magnetic field. These findings exemplify the topological robustness of the once-created skyrmions, and establish metastable skyrmion phases as a fertile ground for technological applications.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it

$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Crystal structure and state diagrams of Co8Zn8Mn4.
Figure 2: Chiral magnetic structures in real space and q space.
Figure 3: Temperature dependence of the metastable SkX.
Figure 4: Field dependence of the metastable SkX at 40 K after FC.

References

  1. Bogdanov, A. N. & Yablonskii, D. A. Thermodynamically stable “vortices” in magnetically ordered crystals. The mixed state of magnets. Sov. Phys. JETP 68, 101–103 (1989).

    Google Scholar 

  2. Mühlbauer, S. et al. Skyrmion lattice in a chiral magnet. Science 323, 915–919 (2009).

    Article  Google Scholar 

  3. Yu, X. Z. et al. Real-space observation of a two-dimensional skyrmion crystal. Nature 465, 901–904 (2010).

    Article  CAS  Google Scholar 

  4. Yu, X. Z. et al. Near room-temperature formation of a skyrmion crystal in thin-films of the helimagnet FeGe. Nat. Mater. 10, 106–109 (2011).

    Article  CAS  Google Scholar 

  5. Nagaosa, N. & Tokura, Y. Topological properties and dynamics of magnetic skyrmions. Nat. Nanotech. 8, 899–911 (2013).

    Article  CAS  Google Scholar 

  6. Heinze, S. et al. Spontaneous atomic-scale magnetic skyrmion lattice in two dimensions. Nat. Phys. 7, 713–718 (2011).

    Article  CAS  Google Scholar 

  7. Romming, N. et al. Writing and deleting single magnetic skyrmions. Science 341, 636–639 (2013).

    Article  CAS  Google Scholar 

  8. Seki, S., Yu, X. Z., Ishiwata, S. & Tokura, Y. Observation of skyrmions in a multiferroic material. Science 336, 198–201 (2012).

    Article  CAS  Google Scholar 

  9. White, J. S. et al. Electric-field-induced skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3 . Phys. Rev. Lett. 113, 107203 (2014).

    Article  CAS  Google Scholar 

  10. Ishiwata, S. et al. Versatile helimagnetic phases under magnetic fields in cubic perovskite SrFeO3 . Phys. Rev. B 84, 054427 (2011).

    Article  Google Scholar 

  11. Kézsmárki, I. et al. Néel-type skyrmion lattice with confined orientation in the polar magnetic semiconductor GaV4S8 . Nat. Mater. 14, 1116–1122 (2015).

    Article  Google Scholar 

  12. Tokunaga, Y. et al. A new class of chiral materials hosting magnetic skyrmions beyond room temperature. Nat. Commun. 6, 7638–7644 (2015).

    Article  CAS  Google Scholar 

  13. Nagaosa, N. & Tokura, Y. Emergent electromagnetism in solids. Phys. Scr. T146, 014020 (2012).

    Article  Google Scholar 

  14. Tokura, Y., Seki, S. & Nagaosa, N. Multiferroics of spin origin. Rep. Prog. Phys. 77, 076501 (2014).

    Article  Google Scholar 

  15. Jonietz, F. et al. Spin transfer torques in MnSi at ultralow current densities. Science 330, 1648–1651 (2010).

    Article  CAS  Google Scholar 

  16. Schulz, T. et al. Emergent electrodynamics of skyrmions in a chiral magnet. Nat. Phys. 8, 301–304 (2012).

    Article  CAS  Google Scholar 

  17. Yu, X. Z. et al. Skyrmion flow near room temperature in ultra-low current density. Nat. Commun. 3, 988 (2012).

    Article  CAS  Google Scholar 

  18. Iwasaki, J., Mochizuki, M. & Nagaosa, N. Current-induced skyrmion dynamics in constricted geometries. Nat. Nanotech. 8, 742–747 (2013).

    Article  CAS  Google Scholar 

  19. Sampaio, J., Cros, V., Rohart, S., Thiaville, A. & Fert, A. Nucleation, stability and current-induced motion of isolated magnetic skyrmions in nanostructures. Nat. Nanotech. 8, 839–844 (2013).

    Article  CAS  Google Scholar 

  20. Hori, T., Shiraish, H. & Ishii, Y. Magnetic properties of β-CoZnMn alloys. J. Magn. Magn. Mater. 310, 1820–1822 (2007).

    Article  CAS  Google Scholar 

  21. Oike, H. et al. Interplay between topological and thermodynamic stability in a metastable magnetic skyrmion lattice. Nat. Phys. 12, 62–67 (2016).

    Article  CAS  Google Scholar 

  22. Ritz, R. et al. Giant generic topological Hall resistivity of MnSi under pressure. Phys. Rev. B 87, 134424 (2013).

    Article  Google Scholar 

  23. Kagawa, F. & Oike, H. Quenching of charge and spin degrees of freedom in condensed matter. Adv. Mater. http://dx.doi.org/10.1002/adma.201601979 (2016).

  24. Grüner, G. The dynamics of charge-density waves. Rev. Mod. Phys. 60, 1129–1181 (1988).

    Article  Google Scholar 

  25. Münzer, W. et al. Skyrmion lattice in the doped semiconductor Fe1−xCoxSi. Phys. Rev. B 81, 041203(R) (2010).

    Article  Google Scholar 

  26. Milde, P. et al. Unwinding of a skyrmion lattice by magnetic monopoles. Science 340, 1076–1080 (2013).

    Article  CAS  Google Scholar 

  27. Gilardi, R. et al. Direct evidence for an intrinsic square vortex lattice in the overdoped high-T c superconductor La1.83Sr0.17CuO4+δ . Phys. Rev. Lett. 88, 217003 (2002).

    Article  CAS  Google Scholar 

  28. Bianchi, A. D. et al. Superconducting vortices in CeCoIn5: toward the Pauli-limiting field. Science 319, 177–180 (2008).

    Article  CAS  Google Scholar 

  29. Yi, S. D., Onoda, S., Nagaosa, N. & Han, J. H. Skyrmions and anomalous Hall effect in a Dzyaloshinskii–Moriya spiral magnet. Phys. Rev. B 80, 054416 (2009).

    Article  Google Scholar 

  30. Park, J.-H. & Han, J. H. Zero-temperature phases for chiral magnets in three dimensions. Phys. Rev. B 83, 184406 (2011).

    Article  Google Scholar 

  31. Lin, S.-Z., Saxena, A. & Batista, C. D. Skyrmion fractionalization and merons in chiral magnets with easy-plane anisotropy. Phys. Rev. B 91, 224407 (2015).

    Article  Google Scholar 

Download references

Acknowledgements

We are grateful to N. Nagaosa, W. Koshibae, S. Zhang, X. Z. Yu, D. Morikawa, T. Nakajima and N. Kanazawa for fruitful discussions and thank D. Lançon for experimental support at ILL. This work was supported by JSPS Grant-in-Aids for Scientific Research (S) No. 24224009, the Swiss National Science Foundation projects 153451 and 166298, and the European Research Council project CONQUEST.

Author information

Author notes

  1. K. Karube and J. S. White: These authors contributed equally to this work.

Authors and Affiliations

  1. RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan

    K. Karube, H. Oike, A. Kikkawa, F. Kagawa, Y. Tokura & Y. Taguchi

  2. Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland

    J. S. White, N. Reynolds & J. L. Gavilano

  3. Laboratory for Quantum Magnetism (LQM), Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

    N. Reynolds & H. M. Rønnow

  4. Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan

    Y. Tokunaga

  5. Department of Applied Physics, University of Tokyo, Bunkyo-ku 113-8656, Japan

    Y. Tokura

Authors
  1. K. Karube
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. J. S. White
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. N. Reynolds
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. J. L. Gavilano
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. H. Oike
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. A. Kikkawa
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. F. Kagawa
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Y. Tokunaga
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. H. M. Rønnow
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Y. Tokura
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Y. Taguchi
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Y.Taguchi, H.M.R. and Y.Tokura jointly conceived the project. The sample preparation was performed by K.K., A.K. and Y.Tokunaga. Neutron diffraction measurements of the nuclear peaks were carried out by J.S.W. A.c. magnetic susceptibility measurements were carried out by K.K., H.O. and F.K. Small-angle neutron scattering measurements were carried out by J.S.W., K.K., N.R. and J.L.G. The results were discussed and interpreted by all the authors.

Corresponding author

Correspondence to K. Karube.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1057 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Karube, K., White, J., Reynolds, N. et al. Robust metastable skyrmions and their triangular–square lattice structural transition in a high-temperature chiral magnet. Nature Mater 15, 1237–1242 (2016). https://doi.org/10.1038/nmat4752

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat4752

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing