Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100080, Peoples R China
; Chinese Acad Sci, Beijing Synchrotron Radiat Facil, Inst High Energy Phys, Beijing 100049, Peoples R China
The mechanisms played by Ag as a surfactant in giant magnetoresistance multilayers were investigated using interface sensitive x-ray anomalous scattering techniques. Analysis on [Cu/Ni70Co30](20) and [Cu/Ag/Ni70Co30](20) multilayers revealed that 6 A thick NiCu and 6 A thick CuNi3Co intermixing regions are formed at the Ni70Co30-on-Cu interfaces of undoped and Ag-doped multilayers, respectively. The Cu-on-Ni70Co30 interfaces in both multilayers are sharp. Annealing causes severe diffusion across both types of interfaces in the undoped multilayer. But the interfaces in the Ag-doped multilayer do not change significantly upon annealing, except that Ag atoms diffuse into the whole Ni70Co30 layer and some parts of the Cu layer. The results suggest that addition of Ag during the deposition suppresses interfacial intermixing. X-ray diffuse scattering profiles show that the interfacial lateral correlation length of the Ag-doped multilayer is longer than that of the undoped multilayer and does not change significantly after annealing, suggesting that the addition of Ag gives rise to smoother interfaces and results in a good thermal stability.