Experimental realization of two-dimensional artificial skyrmion crystals at room temperature

We report the creation of an artificial skyrmion crystal, which is configurable reliably at room temperature. The samples are fabricated by embedding lithography-patterned arrays of micron-sized Co disks onto Co/Pt multilayer films that have perpendicular magnetic anisotropy. Kerr microscopy and magnetic force microscopy reveal that the disks are in the vortex state with controllable circulation. Via comparison of measured hysteresis loops and calculated ones, we find that the sample can be configured into either a skyrmion or a non-skyrmion state. The reproducible and stable skyrmion crystal at room temperature opens the door to direct exploration of their unique topological properties, which has deservedly caused a flurry of theoretical activity.