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(Color online) (a) Geometries of Py nanowires, 10 nm thick and 140 nm wide, with Au layers 40 nm thick (Type I) and 10 nm thick (Type II). In Type I, the Au layers are present above and underneath the Py nanowire to minimise the Oersted field. Type II has Au on the top of the wire and a transverse Oersted field is therefore generated inside the Py nanowire. (b) Current distribution at l Au = 100 nm for a spin current velocity u of 200 m/s in the uncovered part of the wire. (c) Oersted field in Py covered by Au pads when u = 200 m/s in the uncovered part of the wire.
(Color online) (a) DW velocity v as a function of time for u = 130 m/s, 160 m/s, and 200 m/s in the unpatterned Py nanowire. (b) v in terms of the DW displacement for l Au = 100 nm, 150 nm, 200 nm, and 250 nm. (c) DW displacement in terms of time at u = 200 m/s, l Py = 300 nm, and l Au = 150 nm for unpatterned Py nanowire and Py nanowire of Type I. The inset shows the respective velocities. (Fluctuations in the displacement-time relation for the patterned wire are too small to see clearly.) (d) and (e) Snapshot images of internal structures of the moving DWs at u = 200 m/s in an unpatterned Py nanowire (d) and in a Py nanowire of Type I (e). The arrows indicate the DW position before movement.
(Color online) (a) Average DW velocity 〈v〉 as a function of u and l Py at l Au = 150 nm in the Type I structure. At each l Py ranging from 150 nm to 1350 nm, the 〈v〉 was calculated from the time taken by the DW to move 4 μm. The top panel shows the DW velocity in an unpatterned wire. Overlaid on the data for the patterned wire is the DW displacement for the first and second introductions of an antivortex core in an unpatterned wire. (b) 〈v〉 as a function of u for the Type II geometry where the initial DW core magnetization is parallel to the Oersted field. (c) 〈v〉 as a function of u for the Type II geometry where the initial DW core magnetization is antiparallel to the Oersted field.
(Color online) 〈v〉 as a function of the Oersted field Ho and fraction of current shunted for a wire with Au pads in which the thickness of the Au on each side of the wire is varied. Positive Ho indicates Oersted field parallel to the DW core. The asymmetry between positive and negative Ho provides a chirality filter over a wide range of Oersted field and spin current.
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