Electrochemical synthesis and magnetic properties of single-crystal and netlike poly-crystal Ni nanowire arrays

Nickel nanowire (NW) arrays were prepared inside the nanochannels of anodic aluminum oxide (AAO) templates via direct current electrochemical deposition. Through controlling electrolyte composition and electrodeposition parameters, single-crystal and netlike poly-crystal Ni NWs were obtained respectively. Magnetic property measurements reveal that both single-crystal and netlike poly-crystal Ni NW arrays possess a strong magnetic anisotropy with the easy magnetism axis parallel to the NW axis. The single-crystal Ni NW arrays show an enhanced coercivity of 900 Oe and a very high remanence ratio of 0.98 in the parallel-to-NW direction, while the netlike poly-crystal Ni NW arrays present only a coercivity of 600 Oe together with a low remanence ratio of 0.64. The present research is of great importance not only for further studying the relationship between the properties of Ni NWs and their structures, but also for electrochemically producing other metal and alloy NWs with similar structures.