Magnetoresistance of nanocrystalline Co-AlN films

Co-Al-N films with different compositions were deposited by a two-facing target magnetron sputtering method for use as precursor films in the fabrication of magnetoresistive Co-AlN granular films by post-deposition annealing. It is found that the nitrogen flow ratio during sputtering deposition strongly affects the magnetic and electrical properties of Co-AlN films. In the present work, there is an optimum nitrogen flow ratio at which maximum saturation magnetizations and MR ratio (4.6%) are obtained for the annealed film. Such a film also has very high resistivity, of the order of 10⁷ μΩ∈cm. Another important feature of the film is that both Co and AlN are in a crystalline state, which may confer better thermal ability compared with granular films having amorphous matrix.