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Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy

Nature Physics volume 13, pages 170–175 (2017)Cite this article

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Abstract

Magnetic skyrmions are promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their non-zero topological charge leads to a predicted ‘skyrmion Hall effect’, in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we use nanoscale pump–probe imaging to reveal the real-time dynamics of skyrmions driven by current-induced spin–orbit torques. We find that skyrmions move at a well-defined angle ΘSkH that can exceed 30° with respect to the current flow, but in contrast to conventional theoretical expectations, ΘSkH increases linearly with velocity up to at least 100 ms−1. We qualitatively explain our observation based on internal mode excitations in combination with a field-like spin–orbit torque, showing that one must go beyond the usual rigid skyrmion description to understand the dynamics.

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Figure 1: Schematic description of technique and observed skyrmion Hall effect.
Figure 2: Analysis of skyrmions and skyrmion trajectories.
Figure 3: Experimentally observed skyrmion Hall angles of the skyrmion displacement with respect to the current flow direction for different velocities.
Figure 4: The FL-SOT as the origin of the varying skyrmion Hall angle simulated with DL- and FL-SOTs (ξ =5) at different out-of-plane fields.
Figure 5: Experimentally observed skyrmion Hall angles of the skyrmion displacement with respect to the current flow direction for different skyrmion diameters at constant skyrmion velocity.

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References

  1. Dzyaloshinsky, I. A thermodynamic theory of ‘weak’ ferromagnetism of antiferromagnetics. J. Phys. Chem. Solids 4, 241–255 (1958).

    Article  ADS  Google Scholar 

  2. Moriya, T. Anisotropic superexchange interaction and weak ferromagnetism. Phys. Rev. 120, 91–98 (1960).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  6. 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  Google Scholar 

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

    Article  Google Scholar 

  8. Uchida, M. et al. Real-space observation of helical spin order. Science 311, 359–361 (2006).

    Article  ADS  Google Scholar 

  9. Bode, M. et al. Chiral magnetic order at surfaces driven by inversion asymmetry. Nature 447, 190–193 (2007).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  12. Sampaio, J. et al. Nucleation, stability and current-induced motion of isolated magnetic skyrmions in nanostructures. Nat. Nanotech. 8, 839–844 (2013).

    Article  ADS  Google Scholar 

  13. Büttner, F. et al. Dynamics and inertia of skyrmionic spin structures. Nat. Phys. 11, 225–228 (2015).

    Article  Google Scholar 

  14. Rosch, A. Skyrmions: moving with the current. Nat. Nanotech. 8, 160–161 (2013).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  16. Tomasello, R. et al. A strategy for the design of skyrmion racetrack memories. Sci. Rep. 4, 6784 (2014).

    Article  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  20. Zhang, X. et al. Magnetic skyrmion logic gates: conversion, duplication and merging of skyrmions. Sci. Rep. 5, 9400 (2015).

    Article  Google Scholar 

  21. Malozemoff, A. P. & Slonczewski, J. C. Magnetic Domain Walls in Bubble Materials (Academic, 1979).

    Google Scholar 

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

    Article  ADS  Google Scholar 

  23. Romming, N. et al. Field-dependent size and shape of single magnetic skyrmions. Phys. Rev. Lett. 114, 177203 (2015).

    Article  ADS  Google Scholar 

  24. Yuan, S. J. et al. Interfacial effects on magnetic relaxation in Co/Pt multilayers. Phys. Rev. B 68, 134443 (2003).

    Article  ADS  Google Scholar 

  25. Metaxas, P. J. et al. Creep and flow regimes of magnetic domain-wall motion in ultrathin Pt/Co/Pt films with perpendicular anisotropy. Phys. Rev. Lett. 99, 217208 (2007).

    Article  ADS  Google Scholar 

  26. Shellekens, A. J. et al. Determining the Gilbert damping in perpendicularly magnetized Pt/Co/AlOx films. Appl. Phys. Lett. 102, 082405 (2013).

    Article  ADS  Google Scholar 

  27. Jiang, W. et al. Direct observation of the skyrmion Hall effect. Nat. Phys. http://dx.doi.org/10.1038/nphys3883 (2016).

  28. Reichhardt, C. & Reichhardt, C. J. O. Noise fluctuations and drive dependence of the skyrmion Hall effect in disordered systems. New J. Phys. 18, 095005 (2016).

    Article  ADS  Google Scholar 

  29. Schütte, C. & Garst, M. Magnon-skyrmion scattering in chiral magnets. Phys. Rev. B 90, 094423 (2014).

    Article  ADS  Google Scholar 

  30. Qui, X. et al. Angular and temperature dependence of current induced spin–orbit effective fields in Ta/CoFeB/MgO nanowires. Sci. Rep. 4, 4491 (2014).

    Google Scholar 

  31. Hayashi, M. et al. Quantitative characterization of the spin–orbit torque using harmonic Hall voltage measurements. Phys. Rev. B 89, 144425 (2014).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

Work at MIT was primarily supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award #DE-SC0012371 (sample fabrication). G.S.D.B. acknowledges support from C-SPIN, one of the six SRC STARnet Centers, sponsored by MARCO and DARPA. M.K. and the group at Mainz acknowledge support by the DFG (in particular SFB TRR173 Spin + X), the Graduate School of Excellence Materials Science in Mainz (MAINZ, GSC 266), the EU (MultiRev (ERC-2014-PoC 665672), MASPIC (ERC-2007-StG 208162), WALL (FP7-PEOPLE-2013-ITN 608031)), SpinNet, a topical network project of the German Academic Exchange Service (DAAD), and the Research Center of Innovative and Emerging Materials at Johannes Gutenberg University (CINEMA). M.K. thanks ICC-IMR at Tohoku University for their hospitality during a visiting researcher stay at the Institute for Materials Research. B.K. is grateful for financial support by the Carl-Zeiss-Foundation. F.B. acknowledges financial support by the German Research Foundation through grant no. BU 3297/1-1. O.A.T. acknowledges support by the Grants-in-Aid for Scientific Research (Grants No. 25800184, No. 25247056, and No. 15H01009) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan and SpinNet. K.L. gratefully acknowledges financial support by the Graduate School of Excellence Materials Science in Mainz (MAINZ) and the help and advice of Karin Everschor-Sitte and technicians of the Kläui group, especially S. Kauschke. Measurements were carried out at the MAXYMUS end station at Helmholtz-Zentrum Berlin. We thank HZB for the allocation of beamtime. Parts of this research were conducted using the supercomputer Mogon offered by Johannes Gutenberg University Mainz (hpc.uni-mainz.de), which is a member of the AHRP and the Gauss Alliance e.V.

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Authors and Affiliations

  1. Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany

    Kai Litzius, Benjamin Krüger, Pedram Bassirian, Kornel Richter, Robert M. Reeve & Mathias Kläui

  2. Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany

    Kai Litzius & Mathias Kläui

  3. Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany

    Kai Litzius, Johannes Förster, Markus Weigand, Iuliia Bykova, Hermann Stoll & Gisela Schütz

  4. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    Ivan Lemesh, Lucas Caretta, Felix Büttner & Geoffrey S. D. Beach

  5. WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

    Koji Sato

  6. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

    Oleg A. Tretiakov

  7. School of Natural Sciences, Far Eastern Federal University, Vladivostok 690950, Russia

    Oleg A. Tretiakov

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  1. Kai Litzius
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Contributions

M.K. and G.S.D.B. proposed and supervised the study. I.L. and K.L. fabricated devices. I.L. performed the film characterization. K.L., L.C., K.R., P.B., J.F., R.M.R., H.S., G.S., I.B. and M.W. conducted STXM experiments on the MAXYMUS beamline at the BESSY II synchrotron in Berlin. K.L. and M.K. performed and analysed the micromagnetic simulations. B.K., K.S. and O.A.T. derived a Thiele equation to explain the micromagnetic simulations and provided input for the latter. K.L., P.B. and K.R. performed the analytical analysis of the experimental data. F.B. derived the expression for the skyrmion Hall angle as a function of the domain wall width. All authors participated in the discussion and interpreted results. K.L. drafted the manuscript with the help of M.K. and assistance from G.S.D.B. All authors commented on the manuscript.

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Correspondence to Geoffrey S. D. Beach or Mathias Kläui.

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The authors declare no competing financial interests.

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Litzius, K., Lemesh, I., Krüger, B. et al. Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy. Nature Phys 13, 170–175 (2017). https://doi.org/10.1038/nphys4000

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