We have measured the low temperature magnetoresistance (MR) of ferromagnetic cobalt nanowires of 30 nm thickness and widths between 32 and 700 nm. The wires are in situ capped with a 2 nm Pt layer to prevent oxidation. Single wires exhibit sharp resistance peaks at the coercive fields H-c-where H-c increases with decreasing wire width-which can be completely understood in terms of an in-plane switching process. Adding 2 x 2 mu m(2) nucleation pads at the wire ends clearly reduces the coercive fields of the wires. By fabricating wires with two different widths a two-step switching process can be achieved where the wider nanowire switches first. In this case, a single domain wall is introduced in the constriction between the wider and the narrower part of the wire. The MR can be studied in more detail and with higher accuracy by adding additional voltage leads close to the domain wall. The results are discussed to distinguish between contributions resulting from domain wall magnetoresi stance and anisotropic magnetoresistance (AMR).
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机译：我们已经测量了厚度为30 nm，宽度在32至700 nm之间的铁磁钴纳米线的低温磁阻（MR）。导线被原位覆盖2 nm Pt层以防止氧化。单线在矫顽场H-c处表现出尖锐的电阻峰，其中H-c随着线宽的减小而增加，这在平面内切换过程中可以完全理解。在焊丝末端添加2 x 2μm（2）形核垫明显减少了焊丝的矫顽场。通过制造具有两种不同宽度的导线，可以实现两步切换过程，其中较宽的纳米线首先切换。在这种情况下，在电线的较宽和较窄部分之间的收缩处引入了单个畴壁。通过在磁畴壁附近增加额外的电压引线，可以更详细地研究MR，并具有更高的精度。讨论结果以区分由畴壁磁阻和各向异性磁阻（AMR）引起的贡献。
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