Figure 3

(a) Threshold current density J_th needed to depin a skyrmion pinned by a pinning site of depth = 10 nm located at the top edge of the nanowire and the angle of deviation γ of the skyrmion motion to the direction of electron flow as a function of the ratio of non-adiabatic constant of the STT β to the Gilbert damping constant α. At β = 0, pinned skyrmions are not depinned due to the lack of a driving force. Only β is varied while α is kept at a constant value of 0.1. Inset shows the deviation angle γ measured from the center of the skyrmion before and after driving by current. (b) Skyrmion diameter d as a function of applied current density J for ferromagnetic pinning layers located at opposite edges of the nanowire.