Effect of annealing processes on the magneto-resistance in pulsed laser ablated-deposited Ag90Co10 and Co10Cu90 films

Two series of Ag90Co10 and Co10Cu90 films have been produced by the pulsed laser ablation technique. The evolution of the giant magneto-resistance (GMR) as a function of the annealing temperature, in both systems, shows strong differences. In the Ag–Co system, the largest magneto-resistances are observed in the as-deposited sample, whereas the thermal treatment at 350°C for 10 min decreases the magneto-resistance. However, a negligible GMR is observed in the as-deposited sample of the Co–Cu series and a 475°C heat treatment for 10 min produces a maximum of this transport property in our Co–Cu samples. Blocking processes are observed in the low-temperature GMR of the as-deposited Ag–Co sample to 27 K, although no such processes take place in the as-deposited Co–Cu one, even at 4 K, which indicates that the magnetic moments of the Co cluster in the as-deposited Ag–Co samples are larger than the ones in the as-deposited Co–Cu samples. A difference in the solubility of Co in the Cu or in the Ag matrix was proposed as the basis of the difference in sizes of the magnetic clusters in the as-deposited films and consequently in the different thermal dependence of the GMRs of the Ag–Co and Co–Cu systems.