Giant magnetoresistance response in Ag-Co multilayers and nanoparticles

Ag-Co multilayers with very thin Co layers exhibit self-organized nanogranular structure and large values of giant magnetoresistance (GMR). In this work, a third non-magnetic element X (X = Cu, Pt, Si) is added to the Ag layer and the influence of this modification on the structural, magnetic and magnetotransport properties of the samples is examined. We find that the addition of Cu maintains the granular structure and large magnetoresistance values. On the contrary, the samples turn into multilayers with continuous Co layers and small magnetoresistance with increasing Pt concentration. Small magnetoresistance values are also exhibited by the AgSi-Co samples. Post-deposition annealing of the Ag-Co and AgX-Co systems is examined and found to result in structural improvement of the films accompanied by monotonic GMR magnitude decrease. (C) 2003 Elsevier B.V. All rights reserved.