Growth mechanism and magnetic properties of Co nanowire arrays by AC electrodeposition

Co nanowire arrays with diameters of 25 nm, 50 nm and 75 nm were prepared in pores of anodic aluminum oxide (AAO) templates via an AC electrodeposition technique. Filling rate of Co nanowires in the pores of AAO template was studied at various voltages. Studies showed that Co nanowire can be full of the pores of AAO template at high voltage, which suggested a two dimensional (2D) titled plane growth mode for Co nanowire growing up by AC electrodeposition technique. The growth process of Co nanowires was illustrated in detail. Theoretical analysis indicated that thermodynamic factor was responsible for the filling rate of Co nanowires in the pores of AAO template. The magnetic behaviors of Co nanowire arrays with varying diameters were investigated at room temperature. The results have confirmed that coercivity (Hc), remanent magnetization (Mr) and squareness (SQ), measured along wire axis, decrease with increasing of Co nanowires diameter. Moreover, the SQ of Co nanowire arrays with diameter of 25 nm was much higher than those of others in this direction. It can be attributed to both the magnetostatic coupling among the wires and the arrangement of Co grains in the AAO pores. This work will be beneficial for a magnetic media with perpendicular anisotropy to allow a smaller bit size and increase the recording density.