Template synthesis and magnetoresistance property of Ni and Co single nanowires electrodeposited into nanopores with a wide range of aspect ratios

Abstract

Nanopores with a wide range of aspect ratios were fabricated in an anodized aluminium oxide layer on bulk metallic aluminium. The aspect ratios (L/D) were around 20–1000 (pore length, L, 1000–60 000 nm; pore diameter, D, 50–100 nm). For comparison, nanopores in polymer films were also prepared using heavy-ion-track etched polyimide films (L, 70 000 nm; D, 70 nm; L/D = 1000) and polycarbonate films (L, 30 000 nm; D, 100 nm; L/D = 300). The pore diameter of the anodized aluminium oxide layer was controlled by the anodization voltage, while the pore diameter of the heavy-ion-tracked polyimide and polycarbonate films was controlled by the etching time in a sodium hydroxide alkaline solution. Ni and Co homogeneous single nanowires were fabricated using the electrodeposition and in situ contacted techniques in the nanoporous templates. The Ni and Co nanowires with the largest aspect ratios (L/D = 1000) showed around 2.3% and 1.6% of the typical anisotropic magnetoresistance (AMR), and the effects of aspect ratio on the resistance and AMR were investigated.

Magneto-sensitive nickel nanowires fabricated by electrodeposition into multi- and single-ion track templates

“…Therefore, the resistivity is estimated to be around 130 µΩcm. This value confirms that the electrodeposited nanowire has metallic state [19]. Figure 9 displays the angular dependence of the normalized resistance measured at a magnetic field of 10 kOe for a Ni nanowire in a single-channel template with a channel diameter (500±50) nm, θ being the angle between magnetic field and wire axis (= direction of current).…”

“…Using a similar heavy-ion LIGA technique [14][15][16][17][18], metallic nanowires with much higher aspect ratio can be synthesized, however presently still with random positioning. This has been demonstrated for polycarbonate and polyimide at nanochannel densities around 10 8 channels cm -2 [19].…”

Electrodeposition of Metallic Nanowires in Nanoporous Polycarbonate Films

“…Template synthesis technique such as fabricating nano-pores and electrodepositing nanowires requires precise techniques controlling position of each nano-pore, inter-pore distance, pore diameter and pore shape [18][19][20]. Lithographic galvanoforming process using laser, electrons and ions beam could satisfied the above requirements to synthesize new nano-electronic devices.…”

Spin Transport in Self Assembled All-Metal Nanowire Spin Valves: A Study of the Pure Elliott-Yafet Mechanism

“…The device resistance is ~300 Ω which is quite large for an all-metal device. However, this is not a surprise because the conductivities of metal quantum wires can be much less compared to their bulk values 10 . This is because at low dimensions electron mean free path is limited by surface scattering.…”