Oxidation of Copper on the Electrodeposited Co-Ni Alloy Layers in the Co-Ni/Cu Multilayer

In recent years, more attention has been paid on producing ferromagnetic muhilayer by electro deposition (ECD). In this process, metallic muhilayers could be fabricated with acceptable quality and price for magnetic systems such as giant magneto resistance (GMR). It was noticeable that a large amount of oxidation and segregation could be created due to the difference in the interfacial tension between metallic layers. In the present study. copper surface discharge and oxidation was investigated in the electrodeposited Co-NilCu bilayer system using X-ray photoelectron spectroscopy (XPS). secondary ion mass spectroscopy (SIMS) and atomic force microscopy (AFM). The results indicated the existence of a few monolayers of copper oxide on the sud3ce. attributed to discharge and accumulation of copper atoms on the surface during electrodeposition. This phenomenon was explained by lower interfacial tension of the Cu in comparison with the Co and Ni species. Our results also showed that the surface segregation in electrodeposits was increased due to interface charging and. higher sur:tBce diffusion at applied overpotential The effect of inter:tBce charging on the interfacial tension was confirmed by Lippman model Also. the effect of air exposure on the amount of oxidized copper was related to selective oxidation in the Co-NilCu systems with a higher tendency of copper to surface oxidation. These resuhs confirm that the Cu oxidation is a key parameter in the accumulation during deposition and also during air exposure.

Keywords:

Surfilce , Oxidation , Co-Ni , Copper , Electrodeposition