Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 241-246 |
| Number of pages | 6 |
| Journal | Nature Materials |
| Volume | 13 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 2014 Mar |
| Externally published | Yes |
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ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
Cite this
Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect. / Mochizuki, Masahito; Yu, X. Z.; Seki, S.; Kanazawa, N.; Koshibae, W.; Zang, J.; Mostovoy, M.; Tokura, Y.; Nagaosa, N.
In: Nature Materials, Vol. 13, No. 3, 03.2014, p. 241-246.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect
AU - Mochizuki, Masahito
AU - Yu, X. Z.
AU - Seki, S.
AU - Kanazawa, N.
AU - Koshibae, W.
AU - Zang, J.
AU - Mostovoy, M.
AU - Tokura, Y.
AU - Nagaosa, N.
PY - 2014/3
Y1 - 2014/3
N2 - 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.
AB - 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.
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U2 - 10.1038/nmat3862
DO - 10.1038/nmat3862
M3 - Article
AN - SCOPUS:84894482423
VL - 13
SP - 241
EP - 246
JO - Nature Materials
JF - Nature Materials
SN - 1476-1122
IS - 3
ER -