A mechanism to pin skyrmions in chiral magnets.

We propose a mechanism to pin skyrmions in chiral magnetic thin films by introducing local maxima of magnetic exchange strength as pinning centers. The local maxima can be realized by engineering the local density of itinerant electrons. The stationary properties and the dynamical pinning and depinning processes of an isolated skyrmion around a pinning center are studied. We carry out numerical simulations of the Landau-Lifshitz-Gilbert (LLG) equation and find a way to control the position of an isolated skyrmion in a pinning center lattice using electric current pulses. The results are verified by a Thiele equation analysis. We also find that the critical current to depin a skyrmion, which is estimated to have order of magnitude 10(7)-10(8) A m(-2), has linear dependence on the pinning strength.