Figure 2. The top-view of the SOT driven chiral DW motions in the “Straight” and “Bend”.

Red represents + z magnetization, blue represents –z magnetization. (a–d) The “Straight”: 40 nm-wide and 1.28 μm-long Pt(2 nm)/CoFeB(0.6 nm)/MgO. DW motion velocity can reach 400 m/s with a current of 2 × 10¹¹ A/m². DW tilting occurs which agrees with experimental results. (e–h) The “Bend”: external diameter D_ex is 1.024 μm, width d is 40 nm. The gap length of the heavy metal layer L_gap is 100 nm. Current injected into the heavy metal layer for SOT part J_Ring is 3 × 10¹¹ A/m² and leakage current in the gap part inducing STT J_Gap is 1.4 × 10¹² A/m². The different directions of current for these two parts guarantee the uni-direction of DW motions.