Magnetically assembled multiwalled carbon nanotubes on ferromagnetic contacts

A facile method for assembling carbon nanotubes (CNT) on ferromagnetic metal contacts is described. Multiwalled carbon nanotubes (MWNT) with a magnetic cap were fabricated by thermally evaporating nickel on top of a vertical array of MWNTs grown on silicon. Magnetic interaction between the magnets on the nanotubes and lithographically patterned ferromagnetic electrodes caused the relative alignment and directed placement of nanotubes. The lithographically patterned electrodes were further modified using electrochemical deposition to form asymmetric ferromagnetic electrodes as well as improve the electrical and magnetic interactions at the contacts. MWNTs thus assembled showed characteristics that have been established for various nanotube device configurations. This validates the assembling technique for exploring charge- and spin-based electronic devices.