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.

Magnetic antiskyrmions above room temperature in tetragonal Heusler materials

Abstract

Magnetic skyrmions are topologically stable, vortex-like objects surrounded by chiral boundaries that separate a region of reversed magnetization from the surrounding magnetized material1,2,3. They are closely related to nanoscopic chiral magnetic domain walls, which could be used as memory and logic elements for conventional and neuromorphic computing applications that go beyond Moore’s law. Of particular interest is ‘racetrack memory’, which is composed of vertical magnetic nanowires, each accommodating of the order of 100 domain walls, and that shows promise as a solid state, non-volatile memory with exceptional capacity and performance4,5. Its performance is derived from the very high speeds (up to one kilometre per second) at which chiral domain walls can be moved with nanosecond current pulses in synthetic antiferromagnet racetracks. Because skyrmions are essentially composed of a pair of chiral domain walls closed in on themselves, but are, in principle, more stable to perturbations than the component domain walls themselves, they are attractive for use in spintronic applications, notably racetrack memory. Stabilization of skyrmions has generally been achieved in systems with broken inversion symmetry, in which the asymmetric Dzyaloshinskii–Moriya interaction modifies the uniform magnetic state to a swirling state6,7. Depending on the crystal symmetry, two distinct types of skyrmions have been observed experimentally, namely, Bloch7,8 and Néel skyrmions9. Here we present the experimental manifestation of another type of skyrmion—the magnetic antiskyrmion—in acentric tetragonal Heusler compounds with D2d crystal symmetry. Antiskyrmions are characterized by boundary walls that have alternating Bloch and Néel type as one traces around the boundary. A spiral magnetic ground-state, which propagates in the tetragonal basal plane, is transformed into an antiskyrmion lattice state under magnetic fields applied along the tetragonal axis over a wide range of temperatures. Direct imaging by Lorentz transmission electron microscopy shows field-stabilized antiskyrmion lattices and isolated antiskyrmions from 100 kelvin to well beyond room temperature, and zero-field metastable antiskyrmions at low temperatures. These results enlarge the family of magnetic skyrmions and pave the way to the engineering of complex bespoke designed skyrmionic structures.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Figure 1: Skyrmions and antiskyrmions.
Figure 2: Structural and magnetic properties.
Figure 3: Room-temperature antiskyrmions in Mn1.4Pt0.9Pd0.1Sn.
Figure 4: Temperature dependence of antiskyrmions and phase diagram.

Similar content being viewed by others

References

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

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  3. Fert, A., Cros, V. & Sampaio, J. Skyrmions on the track. Nat. Nanotechnol. 8, 152–156 (2013)

    Article  ADS  CAS  Google Scholar 

  4. Parkin, S. S. P. & Yang, S.-H. Memory on the racetrack. Nat. Nanotechnol. 10, 195–198 (2015)

    Article  ADS  CAS  Google Scholar 

  5. Yang, S.-H., Ryu, K.-S. & Parkin, S. S. P. Domain-wall velocities of up to 750 m s−1 driven by exchange-coupling torque in synthetic antiferromagnets. Nat. Nanotechnol. 10, 221–226 (2015)

    Article  ADS  CAS  Google Scholar 

  6. Rößler, U. K., Bogdanov, A. N. & Pfleiderer, C. Spontaneous skyrmion ground states in magnetic metals. Nature 442, 797–801 (2006)

    Article  ADS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  Google Scholar 

  10. 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  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  15. Moreau-Luchaire, C. et al. Additive interfacial chiral interaction in multilayers for stabilization of small individual skyrmions at room temperature. Nat. Nanotechnol. 11, 444–448 (2016)

    Article  ADS  CAS  Google Scholar 

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

    Google Scholar 

  17. Bogdanov, A. N., Rößler, U. K., Wolf, M. & Müller, K. H. Magnetic structures and reorientation transitions in noncentrosymmetric uniaxial antiferromagnets. Phys. Rev. B 66, 214410 (2002)

    Article  ADS  Google Scholar 

  18. Koshibae, W. & Nagaosa, N. Theory of antiskyrmions in magnets. Nat. Commun. 7, 10542 (2016)

    Article  ADS  CAS  Google Scholar 

  19. Zhang, S., Petford-Long, A. K. & Phatak, C. Creation of artificial skyrmions and antiskyrmions by anisotropy engineering. Sci. Rep. 6, 31248 (2016)

    Article  ADS  CAS  Google Scholar 

  20. Tanigaki, T. et al. Real-space observation of short-period cubic lattice of skyrmions in MnGe. Nano Lett. 15, 5438–5442 (2015)

    Article  ADS  CAS  Google Scholar 

  21. Boulle, O. et al. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures. Nat. Nanotechnol. 11, 449–454 (2016)

    Article  ADS  CAS  Google Scholar 

  22. Woo, S. et al. Observation of room-temperature magnetic skyrmions and their current-driven dynamics in ultrathin metallic ferromagnets. Nat. Mater. 15, 501–506 (2016)

    Article  ADS  CAS  Google Scholar 

  23. Jiang, W. et al. Blowing magnetic skyrmion bubbles. Science 349, 283–286 (2015)

    Article  ADS  CAS  Google Scholar 

  24. Jeong, J. et al. Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy. Nat. Commun. 7, 10276 (2016)

    Article  ADS  CAS  Google Scholar 

  25. Nayak, A. K. et al. Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias. Nat. Mater. 14, 679–684 (2015)

    Article  ADS  CAS  Google Scholar 

  26. Meshcheriakova, O. et al. Large noncollinearity and spin reorientation in the novel Mn2RhSn Heusler magnet. Phys. Rev. Lett. 113, 087203 (2014)

    Article  ADS  CAS  Google Scholar 

  27. Li, Y. F. et al. Robust formation of skyrmions and topological Hall effect anomaly in epitaxial thin films of MnSi. Phys. Rev. Lett. 110, 117202 (2013)

    Article  ADS  Google Scholar 

  28. Karube, K. et al. Robust metastable skyrmions and their triangular–square lattice structural transition in a high-temperature chiral magnet. Nat. Mater. 15, 1237–1242 (2016)

    Article  ADS  CAS  Google Scholar 

  29. Oike, H. et al. Interplay between topological and thermodynamic stability in a metastable magnetic skyrmion lattice. Nat. Phys. 12, 62–66 (2016)

    Article  CAS  Google Scholar 

  30. Barker, J. & Tretiakov, O. A. Static and dynamical properties of antiferromagnetic skyrmions in the presence of applied current and temperature. Phys. Rev. Lett. 116, 147203 (2016)

    Article  ADS  Google Scholar 

  31. Chapman, J. N. The investigation of magnetic domain structures in thin foils by electron microscopy. J. Phys. D 17, 623–647 (1984)

    Article  ADS  CAS  Google Scholar 

  32. Beleggia, M. et al. A Fourier approach to fields and electron optical phase-shifts calculations. Ultramicroscopy 96, 93–103 (2003)

    Article  CAS  Google Scholar 

  33. Beleggia, M. et al. Quantitative study of magnetic field distribution by electron holography and micromagnetic simulations. Appl. Phys. Lett. 83, 1435–1437 (2003)

    Article  ADS  CAS  Google Scholar 

  34. Walton, S. K. et al. MALTS: A tool to simulate Lorentz Transmission Electron Microscopy from micromagnetic simulations. IEEE Trans. Magn. 49, 4795–4800 (2013)

    Article  ADS  Google Scholar 

  35. Donahue, M. J. & Porter, D. G. OOMMF User’s Guide, version 1.0, Interagency Report NISTIR 6376 (National Institute of Standards and Technology, Gaithersburg, 1999); available at http://math.nist.gov/oommf

  36. Rohart, S. & Thiaville, A. Skyrmion confinement in ultrathin film nanostructures in the presence of Dzyaloshinskii–Moriya interaction. Phys. Rev. B 88, 184422 (2013)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank H. Blumtritt and N. Schammelt for their help in preparing TEM lamellae for this study. This work was financially supported by the ERC Advanced Grant No. 670166 “SORBET” and the ERC Advanced Grant No. 291472 “Idea Heusler”.

Author information

Authors and Affiliations

Authors

Contributions

A.K.N., C.F. and S.S.P.P. conceived the original idea for the project. A.K.N. performed the LTEM investigations with the help of E.P. and P.W. The bulk materials were synthesized by V.K. and A.K.N. F.D. and R.S. carried out the neutron diffraction study. A.K.N. and R.S. performed the magnetic measurements. T.M. performed the micromagnetic and LTEM image simulations. A.K.N. and S.S.P.P. wrote the manuscript with substantial contributions from all authors.

Corresponding author

Correspondence to Stuart S. P. Parkin.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Reviewer Information Nature thanks A. Hirohata and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Figure 1 Structural characterization at room temperature.

a, b, Room-temperature XRD pattern with Rietveld refinement for Mn1.4PtSn (a) and Mn1.4Pt0.9Pd0.1Sn (b). The circles represent the experimental data (IExpt), the red line corresponds to a simulation (Ical) and the blue line shows the difference (‘Diff’) between the two.

Extended Data Figure 2 Schematic representations of crystal and magnetic structures.

a, Crystal structure of Mn1.4Pt0.9Pd0.1Sn with different atoms shown in different colours. Pd randomly occupies the Pt position. b, Ferrimagnetic arrangement of Mn atoms from different magnetic sublattices. c, Effective ferromagnetic moment in the unit cell. d, Helical modification of the spin arrangement due to Dzyaloshinskii–Moriya interaction along [100] (upper panel) and spin cycloid along [110] (lower panel).

Extended Data Figure 3 Magnetization measurements versus temperature.

a, b, Field dependence of magnetization, M(H), for Mn1.4PtSn (a) and Mn1.4Pt0.9Pd0.1Sn (b) at various temperatures.

Extended Data Figure 4 LTEM measurements at various temperatures and magnetic fields.

af, Under-focused LTEM images of Mn1.4Pt0.9Pd0.1Sn taken at T = 200 K for different magnetic fields H parallel to [001]. gi, Under-focused LTEM images of Mn1.4Pt0.9Pd0.1Sn taken at T = 368 K for different magnetic fields H parallel to [001].

Extended Data Figure 5 Zero-field metastable antiskyrmions.

Under-focused LTEM images of Mn1.4Pt0.9Pd0.1Sn taken at 100 K at zero magnetic field.

Extended Data Figure 6 Simulated magnetic configuration of skyrmions.

ac, Magnetization configurations of Bloch skyrmions (a), antiskyrmions (b) and Néel skyrmions (c). The size of the image corresponds to 280 nm × 280 nm in each case. The arrows correspond to the local in-plane component of the magnetization and the colour represents the out-of-plane component of the magnetization.

Extended Data Figure 7 Simulated LTEM images versus defocus distance.

Simulated LTEM images of Bloch skyrmions, antiskyrmions and Néel skyrmions at various defocus distances Δz.

Extended Data Figure 8 Simulated antiskyrmion phase versus perpendicular magnetic field.

af, OOMMF simulation of the evolution of the antiskyrmion phase as a function of perpendicular field strength, with: a, Hz = 0.09 T, mixed helix and antiskyrmion phase; b, Hz = 0.15 T, mixed helix and antiskyrmion phase; c, Hz = 0.21 T, antskyrmion phase; d, Hz = 0.39 T, antikyrmion phase; e, Hz = 0.47 T, mixed antiskyrmion and spin-polarized phase; f, Hz = 0.50 T, spin-polarized phase.

Extended Data Figure 9 Simulated antiskyrmion phase versus tilt angle.

ae, OOMMF simulations as a function of the tilting angle of the magnetic field (0.24 T) with respect to [110], of: a, 20°; b, 10°; c, 0°; d, −10°; e, −20°.

Extended Data Figure 10 Analysis of the antiskyrmion lattice.

Analysis of an LTEM image of the antiskyrmion lattice at 200 K under a perpendicular field of 0.23 T. The red circles show the position and size of the antiskyrmions. The green lines that connect nearby antiskyrmions indicate a hexagonal lattice. The blue numbers are the lengths of the green lines (in nanometres). The red numbers indicate the angles between the green lines (in degrees).

Extended Data Figure 11 Antiskyrmions size and lattice angle analysis.

a, Field dependence of the antiskyrmion size at various temperatures. The error bars represent the standard deviation of the size distribution. b, Field dependence of the mean angle of the antiskyrmion lattice at different temperatures. The inset shows the corresponding standard deviation of the lattice angles.

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Nayak, A., Kumar, V., Ma, T. et al. Magnetic antiskyrmions above room temperature in tetragonal Heusler materials. Nature 548, 561–566 (2017). https://doi.org/10.1038/nature23466

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature23466

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

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