Ferromagnetism in Hydrogenated N-Doped Amorphous Carbon Films

Room temperature ferromagnetism was found in hydrogenated N-Doped amorphous carbon films (a-CNx:H) prepared by plasma enhanced chemical vapor deposition (CVD). The magnetization of the films changes depending on N content, deposition temperature and annealed temperature. Compared with that of the as-deposited sample, the magnetic moment of the annealed sample had a significant decrease. Among the annealed samples, the film annealed at 450°C possessed the highest magnetization. Higher or lower annealed temperature made the magnetization of the film decrease. Any ferromagnetic impurities didn’t be detected. The ferromagnetism of a-CNx:H film is intrinsic. We believe that N adatoms on the surfaces of the films have localized magnetic moments.