Magnetotransport and coupling in nanostructured Co/Ag thin films

We have studied the electrical resistivity and giant magnetoresistance (GMR ) of [Co(15 Angstrom)/Ag(45 Angstrom)](20)/Ag(45 Angstrom) multilayers trea ted at different annealing temperatures. A simulation based on a formal sol ution of the Boltzmann equation for the electrical resistivity was performe d, and the results compared to the experimental results from 4.2 to 300 K. The simulation shows that both the mean free paths and the transmission coe fficients are affected by the breaking of the magnetic layers: at lower ann ealing temperatures, on account of stress relief and other related processe s, the mean free paths increase, but the minority spin mean free path for e lectrons decreases for anneals above 324 degrees C. A simple parameter to m easure the coupling present in spin valve systems is proposed. This shows a decrease of the coupling in the first stages of the anneals, with a sudden increase in coupling upon breaking the magnetic layers. (C) 2000 Elsevier Science B.V. All rights reserved.