Microstructure and magnetic properties of bamboo-like CoPt/Pt multilayered nanowire arrays

Highly ordered CoPt/Pt multilayered nanowire arrays have been fabricated successfully by double-pulse electro-deposition into the pores of a porous anodic aluminum oxide (AAO) template. It was found that the nanowires had a bamboo-like structure, in which the section lengths were readily adjusted by varying the pulse width and pulse intensity. XRD and EDX pattern indicated that Pt and disordered fcc CoPt structure were formed during electro-deposition. An in plane anisotropy was found in the samples and high coercivity (Hc=1.8 kOe), squareness (Mr/Ms) around 0.35 was obtained in the samples when the field applied perpendicular to wire axis of CoPt/Pt multilayers, the value of which was much higher than that of pure Co nanowires with the same dimension. The high coercivity obtained in the samples can be attributed to the forming disordered fcc CoPt structure during the deposition of Co.