The effect of growth rate enhancement on the magnetic properties and microstructures of ac electrodeposited Co nanowires using non-symmetric reductive/oxidative voltage

Non-symmetric reductive/oxidative voltage was employed to electrodeposit the Co nanowires through the alumina barrier layer into porous aluminum oxide templates grown in oxalic acid. The minimum and maximum oxidative voltages were 12 and 18 V while the maximum difference between the oxidative and reductive voltage was 6 V. The effect of barrier layer modification on the growth rate of the Co nanowires during the electrodeposition procedure was studied. In order to investigate the effects of the non-symmetric electrodeposition voltage on the growth rate the wire's length, the saturation magnetization, the instantaneous and the rms current were measured. Different reductive/oxidative voltages enable us to fabricate electrodeposited nanowires with a wide variety of growth rates. Using same reductive voltage, reducing the oxidative voltage increased the growth rate. At the same reductive voltage (18 V), average growth rate was seen to increase 2.5 times, when the oxidative voltage reduces to 12 V from initially 18 V. The barrier layer thickness of the samples made with different non-symmetric reductive/oxidative deposition voltage was investigated through impedance measurement during the deposition procedure. Reducing the growth rate of deposition reduces the intensity of the (1 0 0) preferential direction of hcp phase thereby improving the magnetic properties. Manipulating the growth rate through non-symmetric electrodeposition enables us to fabricate the Co nanowires with coercivity ranging from 460 to 1850 Oe.