Investigation the Effect of Composition and Annealing on Electrodeposited CoxPt1- X Nanowires

Abstract

Highly ordered Co_xPt_1-x (x ? 0.82) magnetic nanowire arrays of 60 nm diameter have been fabricated successfully by electrodeposition process into the pores of anodic aluminum oxide (AAO) templates. The electrodeposition method was chosen because it is one of the most straightforward, cost-effective, and easy-to-control methods for creating nanowires. It was found that deposition potential is a key factor to control the composition and thus the magnetic properties of the nanowires. The as-deposited Co_xPt_{1- x} nanowires were characterized by XRD to have fcc structure with preferred orientation of (111) or (001) along the nanowire. Co- rich nanowires exhibit ferromagnetic behavior in contrast to near superparamagnetic response of the Pt-rich nanowires. Upon annealing the effects of crystallization cause the decrease of anisotropy along the wire axis for Co₈₂Pt₁₈ nanowires due to the increase of magnetocrystalline anisotropy perpendicular to the wire axis. In the next phase of our work segmented CoPtP/Pt multilayers nanowires are deposited within the AAO template. Such multilayers nanowires are expected to have the high anisotropy due to the formation of ordered Co-Pt alloy phase at the interface. The deposition potential, we discovered, is an important factor in controlling the structure and therefore the magnetic properties of nanowires.