Granular Co/Ag Multilayers : relation between nanostructure, and magnetic and transport properties

The relation between structural properties, magnetization, and magnetoresistance of sputtered Co/Ag multilayers is studied in as-deposited and annealed multilayers with thin Co layers. Nuclear-magnetic-resonance experiments and magnetization measurements showed that decreasing the nominal Co thickness below 10 Å causes a gradual transition from an anisotropic ferromagnetic layered system to a granular system consisting of a layered array of Co pancakes. Annealing extends the granular regime to larger Co thicknesses, reduces the roughness, and transforms the Co clusters to a more isotropic shape. The effect of these structural changes on magnetization and magnetoresistance is discussed