Real-space observation of a two-dimensional skyrmion crystal
Top Cited Papers
- 1 June 2010
- journal article
- letter
- Published by Springer Science and Business Media LLC in Nature
- Vol. 465 (7300), 901-904
- https://doi.org/10.1038/nature09124
Abstract
Crystal order is not restricted to the periodic atomic array, but can also be found in electronic systems such as the Wigner crystal1 or in the form of orbital order2, stripe order3 and magnetic order. In the case of magnetic order, spins align parallel to each other in ferromagnets and antiparallel in antiferromagnets. In other, less conventional, cases, spins can sometimes form highly nontrivial structures called spin textures4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23. Among them is the unusual, topologically stable skyrmion spin texture, in which the spins point in all the directions wrapping a sphere4,5,6,7. The skyrmion configuration in a magnetic solid is anticipated to produce unconventional spin–electronic phenomena such as the topological Hall effect24,25,26. The crystallization of skyrmions as driven by thermal fluctuations has recently been confirmed in a narrow region of the temperature/magnetic field (T–B) phase diagram in neutron scattering studies of the three-dimensional helical magnets MnSi (ref. 17) and Fe1−xCoxSi (ref. 22). Here we report real-space imaging of a two-dimensional skyrmion lattice in a thin film of Fe0.5Co0.5Si using Lorentz transmission electron microscopy. With a magnetic field of 50–70 mT applied normal to the film, we observe skyrmions in the form of a hexagonal arrangement of swirling spin textures, with a lattice spacing of 90 nm. The related T–B phase diagram is found to be in good agreement with Monte Carlo simulations. In this two-dimensional case, the skyrmion crystal seems very stable and appears over a wide range of the phase diagram, including near zero temperature. Such a controlled nanometre-scale spin topology in a thin film may be useful in observing unconventional magneto-transport effects.Keywords
This publication has 26 references indexed in Scilit:
- Skyrmion lattice in the doped semiconductorPhysical Review B, 2010
- Deconfined Quantum Critical PointsScience, 2004
- Orbital Physics in Transition-Metal OxidesScience, 2000
- Spinor Bose Condensates in Optical TrapsPhysical Review Letters, 1998
- Evidence for stripe correlations of spins and holes in copper oxide superconductorsNature, 1995
- Skyrmions and the crossover from the integer to fractional quantum Hall effect at small Zeeman energiesPhysical Review B, 1993
- Magnetic Phase Diagram of MnSi near Critical Temperature Studied by Neutron Small Angle ScatteringJournal of the Physics Society Japan, 1984
- Helical spin structure in manganese silicide MnSiSolid State Communications, 1976
- A unified field theory of mesons and baryonsNuclear Physics, 1962
- On the Interaction of Electrons in MetalsPhysical Review B, 1934