The composition and the annealing effect on the giant magnetoresistance of Co-Cu granular films fabricated by RF sputtering were investigated by TEM and NMR analysis. The maximum MR of 17% at 4.2K could be obtained at cobalt composition of 20 at%. Fro...
The composition and the annealing effect on the giant magnetoresistance of Co-Cu granular films fabricated by RF sputtering were investigated by TEM and NMR analysis. The maximum MR of 17% at 4.2K could be obtained at cobalt composition of 20 at%. From the TEM and NMR analysis, it has been found that the size of cobalt particles and the composition profile near the interfaces of cobalt particles are almost invariable with increase of cobalt concentration, while the interparticle distance decreases. Therefore, it could be concluded that the interparticle distance was mainly responsible for the existence of the maximum MR with respect to the cobalt composition in this system. According to the analysis of NMR spectrum, annealing of the films sharpened the composition profile of the interface between the cobalt particles and the copper matrix, which resulted in enhancement of the GMR values.