Template-based Synthesis and Magnetic Properties of Cobalt Nanotube Arrays

Cobalt nanotube arrays embedded in AAO templates are synthesized by direct electrodeposition with low current density. The nanotubes exhibit an hcp structure with the easy axis perpendicular to the tube. MFM imaging shows only a weak magnetic signal and SQUID measurements reveal sheared hysteresis for the field parallel to the tube axis. Combined with theoretical modeling, we confirm that the magnetization curls circumferentially around the tube wall in small external fields.