Figure 2

Conversions between skyrmions and antiskyrmions.

The top panels show the snapshots of the magnetization configuration at four selected times corresponding to the vertical lines in the middle and bottom panels; the middle panels show the time evolution of the average spin components m_x, m_y, m_z; the bottom panels show the time evolution of the skyrmion number Q_s. (a), Conversion between a skyrmion and a skyrmion with identical out-going helicity: the D in the sample is 3.5 mJ m⁻²; the background points +z; a current density of 3 × 10¹² A m⁻² (the value is of the input or output side, similarly hereinafter) is applied along −x for 0 ns < t < 0.56 ns followed by a relaxation (highlighted by the gray shadows) until t = 1 ns. (b), Conversion between a skyrmion and a skyrmion with opposite in-going helicity: the D is 3.5 mJ m⁻² in the input side and −3.5 mJ m⁻² in the output side, while a gradient transition from 3.5 mJ m⁻² to −3.5 mJ m⁻² is set in the narrow channel; the background points +z; a current density of 3 × 10¹² A m⁻² is applied along −x for 0 ns < t < 0.51 ns and then is the relaxation until t = 1 ns. (c), Conversion between a skyrmion and an anti-skyrmion with opposite in-going helicity: the D in the sample is 3.5 mJ m⁻²; the background of the input side points +z, while it points −z in the output side; a current density of 2.67 × 10¹² A m⁻² is applied along −x for 0 ns < t < 0.51 ns followed by a relaxation until t = 1 ns. (d), Conversion between a skyrmion and an anti-skyrmion with identical out-going helicity: the profile of D is the same as that in b and the profile of background is the same as that in c; a current density of 2.67 × 10¹² A m⁻² is applied along −x for 0 ns < t < 0.51 ns followed by a relaxation until t = 1 ns. The color scale has been used throughout this paper.