Magnetic properties of carbon nanotubes grown on Fe catalyst layer by microwave plasma enhanced chemical vapor deposition

Abstract

The magnetic properties of carbon nanotube films grown on an Fe catalyst layer were investigated. The easy magnetization direction of the nanotube films was perpendicular to the film plane when the growth time was more than 2 min. In these films, conical Fe catalyst particles could be found at the tips of the nanotubes. The origin of the perpendicular magnetic anisotropy of these films was considered to be due to the anisotropic shape of the conical Fe catalyst particles at the tips. A large perpendicular coercivity of about 1 kOe was obtained in a nanotube film grown for 10 min.