Individual skyrmions in helimagnets

The novel physics and promising applications of magnetic skyrmions in helimagnets have attracted great attentions in the past years. Magnetic skyrmions are topologically protected spin textures in which the local moments on a two dimensional lattice point in all directions with a topologically nontrivial mapping to the unit sphere. The skyrmion radius, ranging from about 3 nm to 100 nm, is controlled by strength of the Dzyaloshinskii-Moriya interaction induced by inversion symmetry breaking. Furthermore, a skyrmion enjoys extra stability as a stable state under various temperatures, and can be driven by a tiny electric current or temperature gradient. These properties suggest future processing applications exploiting such topological spin texture as the information carrier. To this end, single bit operation must be achieved. However, up to now, most skyrmions are observed in the crystalline form, which forbids skyrmion-based applications. It is thus a challenge to realize individual skyrmion states. In this talk, I would present our recent theoretical and experimental efforts in achieving this goal.