Giant magnetoresistance in Fe and Co based spin valve structures

Giant magnetoresistance (GMR) effects up to 7% have been observed in Fe/Cu/ Co spin valve structures. The samples have been grown by ion beam sputterin g at room temperature on a glass substrate covered by Cr buffer layer. The best results have been obtained for the sandwich in which a 0.5 nm Co thin layer has been deposited between Fe and Cu layer with the following structu re: Cr-3nm/Fe-3nm/Co-0.5nm/Cu-3nm/CO5nm/Cu-2nm/Cr-2nm. The role of the thin Co layer is to increase the spin-dependent scattering centers. Annealing t reatments during 2 h have been performed on this sample at different temper ature in order to study the thermal stability. A progressive increase of th e GMR has been observed for the annealing at 200 and 250 degreesC, while at 300 degreesC, the GMR completely disappears. Rutherford back scattering (R BS) spectroscopy has been used to explain the physical origin of this drop, which is attributed to the total interdiffusion through grains boundaries between Fe, Co and Cu layers. (C) 2001 Elsevier Science B.V. All rights res erved.