Nature Mater. http://doi.org/7qj (2015)
The stabilization of skyrmions in different magnetic materials has been one of the more arresting developments in condensed-matter physics of the past few years. Named after the particle physicist Tony Skyrme, these vortex-like excitations share the same topology as a set of magnetic moments wrapped around a sphere. Although their microscopic origin has long been known, the extent of their stability to external perturbations has come as a pleasant (and potentially useful) surprise.
One of the remarkable properties of skyrmions is that under suitable conditions they can order into periodic arrays, known as skyrmion lattices, which in many ways resemble a close-packed arrangement of spheres. These are mostly observed in chiral magnetic crystals, but so far they have always consisted of Bloch-like domain walls, in which the spins rotate in the plane parallel to the domain boundary.
Now, Alois Loidl and colleagues have reported the observation of a Néel-type skyrmion lattice in the magnetic semiconductor GaV4S8. In this case, the excitations can be described by a superposition of spin cycloids, in which the spins rotate in a plane perpendicular to the domain boundary — an arrangement named after Louis Néel, the discoverer of antiferromagnetism.
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Taroni, A. Skyrme meets Néel. Nature Phys 11, 800 (2015). https://doi.org/10.1038/nphys3511