Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect

M. Mochizuki*, X. Z. Yu, S. Seki, N. Kanazawa, W. Koshibae, J. Zang, M. Mostovoy, Y. Tokura, N. Nagaosa

*この研究の対応する著者

研究成果: Article査読

226 被引用数 (Scopus)

抄録

Spontaneously emergent chirality is an issue of fundamental importance across the natural sciences. It has been argued that a unidirectional (chiral) rotation of a mechanical ratchet is forbidden in thermal equilibrium, but becomes possible in systems out of equilibrium. Here we report our finding that a topologically nontrivial spin texture known as a skyrmion-a particle-like object in which spins point in all directions to wrap a sphere-constitutes such a ratchet. By means of Lorentz transmission electron microscopy we show that micrometre-sized crystals of skyrmions in thin films of Cu 2 OSeO 3 and MnSi exhibit a unidirectional rotation motion. Our numerical simulations based on a stochastic Landau-Lifshitz-Gilbert equation suggest that this rotation is driven solely by thermal fluctuations in the presence of a temperature gradient, whereas in thermal equilibrium it is forbidden by the Bohr-van Leeuwen theorem. We show that the rotational flow of magnons driven by the effective magnetic field of skyrmions gives rise to the skyrmion rotation, therefore suggesting that magnons can be used to control the motion of these spin textures.

本文言語English
ページ(範囲)241-246
ページ数6
ジャーナルNature Materials
13
3
DOI
出版ステータスPublished - 2014 3月
外部発表はい

ASJC Scopus subject areas

  • 化学 (全般)
  • 材料科学(全般)
  • 凝縮系物理学
  • 材料力学
  • 機械工学

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