Thermally driven ratchet motion of a skyrmion microcrystal and topological magnon Hall effect
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- 26 January 2014
- journal article
- letter
- Published by Springer Nature in Nature Materials
- Vol. 13 (3), 241-246
- https://doi.org/10.1038/nmat3862
Abstract
Spontaneously emergent chirality is an issue of fundamental importance across the natural sciences1. 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 equilibrium2. 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 sphere3—constitutes such a ratchet. By means of Lorentz transmission electron microscopy we show that micrometre-sized crystals of skyrmions in thin films of Cu2OSeO3 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 theorem4,5. 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.Keywords
This publication has 27 references indexed in Scilit:
- Universal current-velocity relation of skyrmion motion in chiral magnetsNature Communications, 2013
- Observation of Skyrmions in a Multiferroic MaterialScience, 2012
- Real-Space Observation of Skyrmion Lattice in Helimagnet MnSi Thin SamplesNano Letters, 2012
- Skyrmion flow near room temperature in an ultralow current densityNature Communications, 2012
- MagnonicsJournal of Physics D: Applied Physics, 2010
- Real-space observation of a two-dimensional skyrmion crystalNature, 2010
- Skyrmion lattices in metallic and semiconducting B20 transition metal compoundsJournal of Physics: Condensed Matter, 2010
- Skyrmions and anomalous Hall effect in a Dzyaloshinskii-Moriya spiral magnetPhysical Review B, 2009
- Thermal Fluctuations of a Single-Domain ParticlePhysical Review B, 1963
- A unified field theory of mesons and baryonsNuclear Physics, 1962