Anomalous direction for skyrmion bubble motion

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Abstract

Magnetic skyrmions are localized topological excitations that behave as particles and can be mobile, with great potential for novel data storage devices. In this work, the current-induced dynamics of large skyrmion bubbles is studied. When skyrmion motion in the direction opposite to the electron flow is observed, this is usually interpreted as a perpendicular spin current generated by the spin Hall effect exerting a torque on the chiral N\'{e}el skyrmion. By designing samples in which the direction of the net generated spin current can be carefully controlled, we surprisingly show that skyrmion motion is always against the electron flow, irrespective of the net vertical spin-current direction. We find that a negative bulk spin-transfer torque is the most plausible explanation for the observed results, which is qualitatively justified by a simple model that captures the essential behaviour. These findings demonstrate that claims about the skyrmion chirality based on their current-induced motion should be taken with great caution.
Original languageEnglish
Article number1807.07365
JournalarXiv
Volume2018
Publication statusPublished - 19 Jul 2018

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bubbles
torque
data storage
chirality
Hall effect
electrons
excitation

Keywords

  • cond-mat.mtrl-sci
  • physics.app-ph

Cite this

@article{c0f88bc333a64b7790536b960f6bc1fc,
title = "Anomalous direction for skyrmion bubble motion",
abstract = "Magnetic skyrmions are localized topological excitations that behave as particles and can be mobile, with great potential for novel data storage devices. In this work, the current-induced dynamics of large skyrmion bubbles is studied. When skyrmion motion in the direction opposite to the electron flow is observed, this is usually interpreted as a perpendicular spin current generated by the spin Hall effect exerting a torque on the chiral N\'{e}el skyrmion. By designing samples in which the direction of the net generated spin current can be carefully controlled, we surprisingly show that skyrmion motion is always against the electron flow, irrespective of the net vertical spin-current direction. We find that a negative bulk spin-transfer torque is the most plausible explanation for the observed results, which is qualitatively justified by a simple model that captures the essential behaviour. These findings demonstrate that claims about the skyrmion chirality based on their current-induced motion should be taken with great caution.",
keywords = "cond-mat.mtrl-sci, physics.app-ph",
author = "Ummelen, {Fanny C.} and Wijkamp, {Tijs A.} and Tom Lichtenberg and Duine, {Rembert A.} and Bert Koopmans and Swagten, {Henk J. M.} and Reinoud Lavrijsen",
year = "2018",
month = "7",
day = "19",
language = "English",
volume = "2018",
journal = "arXiv",
publisher = "Cornell University Library",

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Anomalous direction for skyrmion bubble motion. / Ummelen, Fanny C.; Wijkamp, Tijs A.; Lichtenberg, Tom; Duine, Rembert A.; Koopmans, Bert; Swagten, Henk J. M.; Lavrijsen, Reinoud.

In: arXiv, Vol. 2018, 1807.07365, 19.07.2018.

Research output: Contribution to journalArticleAcademic

TY - JOUR

T1 - Anomalous direction for skyrmion bubble motion

AU - Ummelen, Fanny C.

AU - Wijkamp, Tijs A.

AU - Lichtenberg, Tom

AU - Duine, Rembert A.

AU - Koopmans, Bert

AU - Swagten, Henk J. M.

AU - Lavrijsen, Reinoud

PY - 2018/7/19

Y1 - 2018/7/19

N2 - Magnetic skyrmions are localized topological excitations that behave as particles and can be mobile, with great potential for novel data storage devices. In this work, the current-induced dynamics of large skyrmion bubbles is studied. When skyrmion motion in the direction opposite to the electron flow is observed, this is usually interpreted as a perpendicular spin current generated by the spin Hall effect exerting a torque on the chiral N\'{e}el skyrmion. By designing samples in which the direction of the net generated spin current can be carefully controlled, we surprisingly show that skyrmion motion is always against the electron flow, irrespective of the net vertical spin-current direction. We find that a negative bulk spin-transfer torque is the most plausible explanation for the observed results, which is qualitatively justified by a simple model that captures the essential behaviour. These findings demonstrate that claims about the skyrmion chirality based on their current-induced motion should be taken with great caution.

AB - Magnetic skyrmions are localized topological excitations that behave as particles and can be mobile, with great potential for novel data storage devices. In this work, the current-induced dynamics of large skyrmion bubbles is studied. When skyrmion motion in the direction opposite to the electron flow is observed, this is usually interpreted as a perpendicular spin current generated by the spin Hall effect exerting a torque on the chiral N\'{e}el skyrmion. By designing samples in which the direction of the net generated spin current can be carefully controlled, we surprisingly show that skyrmion motion is always against the electron flow, irrespective of the net vertical spin-current direction. We find that a negative bulk spin-transfer torque is the most plausible explanation for the observed results, which is qualitatively justified by a simple model that captures the essential behaviour. These findings demonstrate that claims about the skyrmion chirality based on their current-induced motion should be taken with great caution.

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