Real space observation of skyrmion polycrystallization and its domain boundary behavior in FeGe1-xSix

In magnetic skyrmion crystals (SkXs), the quality of skyrmion ordering affects the motion under electric current and temperature gradient. However, the crystalline nature itself remains an open issue. We report the observation of skyrmion polycrystallization in FeGe1-xSix as a function of x by Lorentz transmission electron microscopy. With increasing x, the SkX changes from single crystalline to polycrystalline, concomitantly with the formation of the interfaces referred to as domain boundaries. In situ observations have revealed that the domain boundary formation competes the tendency to accommodate the differences between orientations of the SkX. (C) 2015 The Japan Society of Applied Physics