Effect of pH on Structure and Magnetic Properties of Electrodeposited CoNiP Nanowires

Ordered CoNiP nanowire arrays with average diameter of 200 nm have been fabricated by electrodeposition into polycarbonate templates at different pH levels. X-ray diffraction analysis and high-resolution transmission electron microscopy confirmed the quality of the fabricated nanowires. Magnetic measurements revealed that the magnetic anisotropy of the nanowires was significantly altered by varying the pH level of the electrolytic bath. With increasing pH level, the coercive field (Hc) and the remanent to saturation magnetization ratio (Mr/Ms) rapidly increased in the pH range of 2.0 to 3.5 and tended to saturate for higher levels of pH. The CoNiP nanowires were found to transform from soft- to hard-magnetic characteristics when the pH level exceeded a critical value of ∼3.5, at which the maximum coercivity of 1430 Oe was achieved.