Tunneling magnetoresistance in Ag/Co nanoparticle composites

Nanocomposite materials, consisting of ensembles of Ag and Co nanoparticles, have been successfully fabricated, with various compositions and packing densities. The transport and magnetic characteristics of the compounds were studied. In particular, a crossover from a positive magnetoresistance (MR) at low applied magnetic fields to a negative magnetoresistance at high applied magnetic fields was observed. The behaviors could be understood by the spin-dependent tunneling mechanism, known as tunneling magnetoresistance.