Enhancement of Perpendicular Anisotropy of Co/Cu Multilayer Nanowires by Phase Doping

A multisegment structure of Co/Cu nanowires with tunable perpendicular anisotropy, associated with phase transformation, was fabricated. The mixed crystal structure, formed by doping nano grains of the hcp phase into the fcc phase in the cobalt structure, markedly improves the perpendicular anisotropy. Cobalt nano grains with the hcp phase with a preferred orientation, which were transformed from (100) to (002), by doping fcc nano grain with high preferred (111) orientation and additionally the effective magnetocrystalline energy density of mixed structure was increased, the perpendicular magnetic anisotropy can be enhanced and tunable. The magnetoresistance ratios along the parallel and perpendicular axes of nanowires are 23.4% and 7.2% respectively. This novel approach promises to be of strong interest for subsequent fabrication of phase-locked arrays of spin transfer nano-oscillators with increased output power for microwave applications.