Synthesis and magnetic characterization of a Cu80Co20 thin film obtained by electrodeposition technique

A granular Cu80Co20 alloy was elaborated by a low cost electrodeposition technique consisting in reducing simultaneously the Cu2+ and Co2+ ions onto a silicon substrate. The deposition parameters were determined from current-potential curves. The structure of the film was characterized down to the atomic scale by transmission electron microscopy and atom probe tomography. The results show that the as-deposited Cu80Co20 thin film consists mainly of a paramagnetic Cu-Co solid solution containing 10-30% of Co, in which pure Co superparamagnetic nanoparticles are dissolved. Annealing at 500 °C for 1 h leads to the decomposition of the Cu-Co solid solution into purified Cu matrix containing ferromagnetic Co-rich precipitates. The magnetoresistance effect decreases after the heat treatment, in relation with the disappearance of the superparamagnetic Co nanoparticles upon annealing.