Skyrmions are peculiar defects of certain magnetic materials. Spins in a plane start to spiral around a central point, gaining a perpendicular component that grows spiralling inward to a singular out-of-plane central spin. This example is a practical realisation of a topolological defect.This defect is realised in materials lacking inversion symmetry, such as MnSi, and it may give rise to regular arrangements of defects, or skyrmion lattices. Have a look here if you have access to Science (e.g. from the DiFeST). Out-of-plane spins at surfaces are easier to detect, hence ideal for reading them as magnetic bits. For this reason skyrmionic materials are promising for magnetic and spintronic(*) devices.NMR and μSR are tools of choice for investigating such materials. Experiments on Ba2CuGe2O7, a new skyrmion-candidate crystal, are under way.Image credit TUM (*) Spintronics is the analogue of electronics where the electron (ore hole) spin rather than its electric charge, is the quantity of interest. It is relevant if one of the components of the device is e.g. a half metal. In a half metal the carriers of opposite spins occupy half bands that cross and do not cross the Fermi level, EF , respectively. In consequence the bands that do not cross EF are either completely full or completely empty, and do not take part in conduction, whereas the others are partially full and contribute to a finite conductivity. Therefore the material behaves as a metal with carriers that are totally spin polarized, and one may think of manipulating these currents e.g. by magnetic gates.For details ask De Renzi
