Letter | Published:

Magnetic antiskyrmions above room temperature in tetragonal Heusler materials

Nature volume 548, pages 561566 (31 August 2017) | Download Citation

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.

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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

Author notes

    • Ajaya K. Nayak

    Present address: School of Physical Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, Jatni 752050, India.

Affiliations

  1. Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany

    • Ajaya K. Nayak
    • , Tianping Ma
    • , Peter Werner
    • , Eckhard Pippel
    •  & Stuart S. P. Parkin
  2. Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany

    • Vivek Kumar
    • , Roshnee Sahoo
    •  & Claudia Felser
  3. Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette, France

    • Franoise Damay
  4. IFW Dresden, PO Box 270116, 01171 Dresden, Germany

    • Ulrich K. Rößler

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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.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Stuart S. P. Parkin.

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

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https://doi.org/10.1038/nature23466

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