Preparation of cobalt nanowires in porous aluminum oxide: Study of the effect of barrier layer

High-density cobalt (Co) nanowires (NWs) were fabricated using porous anodized aluminum oxide as a template. Measurement results show a high magnetic performance for NWs with a coercivity of about 1750 Oe and strong magnetic anisotropy with an easy axis parallel to the NW direction. We have investigated the effect of alternating current (AC) electrodeposition frequency on the magnetic properties of NW samples. We show that understanding the effect of barrier layer is critical for controlling the rate of NW electrodeposition. A circuit model is proposed that accurately describes the role of the barrier and interfacial layers during deposition. Results obtained by simulation of the circuit show an excellent agreement with experimental results for different frequencies and voltages. It is shown that the amount of electrodeposited material can be estimated based on the difference between the anodic and cathodic half cycles in the electrodeposited current. Use of higher frequency leads to more symmetrical half cycles and smaller electrodeposited material.